0000893818 bf3:S000004278Member 2025-12-31 2025-12-31 0000893818 bf3:S000004279Member 2025-12-31 2025-12-31 0000893818 bf3:S000004280Member 2025-12-31 2025-12-31 0000893818 bf3:S000022024Member 2025-12-31 2025-12-31 0000893818 bf3:S000029260Member 2025-12-31 2025-12-31 0000893818 bf3:S000029261Member 2025-12-31 2025-12-31 0000893818 bf3:S000029262Member 2025-12-31 2025-12-31 0000893818 bf3:S000057862Member 2025-12-31 2025-12-31 0000893818 bf3:S000066172Member 2025-12-31 2025-12-31 0000893818 bf3:S000086334Member 2025-12-31 2025-12-31 0000893818 2025-12-31 2025-12-31 false 2025-12-31 497 0000893818 N-1A <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses entitled “Fund Overview — Key Facts About BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">LifePath Dynamic Retirement Fund allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index. Because the Fund is in its most conservative phase, its allocation generally does not become more conservative over time, although its allocation may change to maintain the Fund’s risk profile.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles, such as exchange-traded funds, that invest in commodities and are designed to provide investment exposure to physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in BlackRock Cayman LifePath Dynamic Retirement Fund, Ltd. (the “Dynamic Retirement Subsidiary”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. Allocations to the Dynamic Retirement Subsidiary will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. The Dynamic Retirement Subsidiary may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the Dynamic Retirement Subsidiary’s derivative positions. The Dynamic Retirement Subsidiary (unlike the Fund) may invest without limitation in commodity-related instruments. However, the Dynamic Retirement Subsidiary is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup><sup style="font-size: 75%; vertical-align: top;"> </sup>Dynamic 2040 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup><sup style="font-size: 75%; vertical-align: top;"> </sup>Dynamic 2040 Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses entitled “Fund Overview — Key Facts About BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">LifePath Dynamic Retirement Fund allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index. Because the Fund is in its most conservative phase, its allocation generally does not become more conservative over time, although its allocation may change to maintain the Fund’s risk profile.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles, such as exchange-traded funds, that invest in commodities and are designed to provide investment exposure to physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in BlackRock Cayman LifePath Dynamic Retirement Fund, Ltd. (the “Dynamic Retirement Subsidiary”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. Allocations to the Dynamic Retirement Subsidiary will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. The Dynamic Retirement Subsidiary may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the Dynamic Retirement Subsidiary’s derivative positions. The Dynamic Retirement Subsidiary (unlike the Fund) may invest without limitation in commodity-related instruments. However, the Dynamic Retirement Subsidiary is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS III</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(each, a “Fund” and collectively, the “Funds”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated September 29, 2026 to the Prospectuses of each Fund,</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">each dated April 30, 2026, as amended or supplemented to date (the “Prospectuses”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">On September 15, 2026, the Board of Trustees of the Funds approved the formation of Cayman Islands subsidiaries for the Funds that invest primarily in certain commodity-related instruments.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective immediately, the following changes are made to the Prospectuses, as applicable:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Investment Strategies of the Fund” is hereby deleted in its entirety and replaced with the following:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">[The Fund] allocates and reallocates its assets among a combination of equity, bond, multi-asset and money market funds (the “Underlying Funds”) and derivatives and commodity-related instruments in proportions based on its own comprehensive investment strategy. Under normal circumstances, the Fund intends to invest primarily in affiliated open‑end funds and affiliated exchange-traded funds (“ETFs”), some of which may be index funds.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may, when consistent with its investment goal, buy or sell options or futures, or enter into total return swaps and foreign currency transactions (collectively, commonly known as derivatives). The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may use derivatives as a substitute for taking a position in an Underlying Fund and/or as part of a strategy to reduce exposure to certain risks. The Fund may also use derivatives to enhance return, in which case their use may involve leveraging risk. Derivatives generally will increase or decrease the Fund’s equity or fixed income allocations for purposes of the glide path by the notional amount of such derivatives, except that</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">derivatives used to manage currency exposure will not be allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may invest up to 10% of its net assets in Underlying Funds that are multi-asset funds designed to have a lower correlation to traditional assets such as equities or fixed income (such Underlying Funds, “Tactical Allocation Underlying Funds”). The allocation to such Tactical Allocation Underlying Funds is designed to seek to improve overall portfolio diversification and enhance returns. Allocations to such Tactical Allocation Underlying Funds will not be allocated to the Fund’s equity or fixed income allocations for the purposes of the glide path. In addition, the Fund may make allocations to currency exposure, commodity-related investments and money market funds that are not allocated to the Fund’s equity or fixed income allocations for purposes of the glide path.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund is designed for investors expecting to retire or to begin withdrawing assets around the year [year]. The Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for the Fund and to determine the Fund’s allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Certain Underlying Funds may invest in equity securities of issuers that are primarily engaged in or related to the real estate industry, real estate investment trusts (“REITs”), infrastructure companies, foreign securities, emerging market securities, below investment-grade bonds, commodity-related instruments and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a commodity, a currency or an index.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Under normal circumstances, the asset allocation between equity and fixed income assets will change over time according to a “glide path” as the Fund approaches its target date. The glide path below represents the shifting of these two asset classes over time. As the glide path shows, the Fund’s asset mix between equity and fixed income assets becomes more conservative — prior to retirement — as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following chart illustrates the glide path — the target allocation to the equity asset class as the Fund approaches its target date.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; text-align: center;"> <img alt="LOGO" src="g113371g01a03.jpg" style="width: 4.43667in; height: 2.64in;"/> </div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The following table lists the target allocations to equity and fixed income asset classes (each as a percentage of the Fund’s net assets) by years until retirement:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; width: 100%; border-spacing: 0px; margin: 0 auto;"> <tr> <td style="width: 68%;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 38pt;"></td> <td></td> <td></td> <td style="width: 38pt;"></td> <td style="vertical-align: bottom; width: 15%;"></td> <td style="width: 29pt;"></td> <td></td> <td></td> <td style="width: 29pt;"></td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"><span style="font-weight: bold;">Years Until Retirement</span></td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Equity Funds</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">(Includes REITs)<sup style="font-size: 75%; vertical-align: top;">I</sup></div> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td colspan="4" style="border-bottom: 0.75pt solid #000000; vertical-align: bottom; text-align: center;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Fixed‑Income</div> <div style="margin-top: 0pt; margin-bottom: 1pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Funds<sup style="font-size: 75%; vertical-align: top;">1</sup></div> </td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    45</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    40</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    35</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    30</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">99</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">1</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    25</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">96</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">4</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    20</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">90</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">10</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    15</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">81</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">19</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">    10</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">71</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">29</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt; background-color: #d8d8d8;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     5</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">59</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">41</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> <tr style="page-break-inside: avoid; font-family: times new roman; font-size: 10pt;"> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;">     0</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;">  </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">40</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: bottom;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top;"> </td> <td style="border-bottom: 0.75pt solid #000000; vertical-align: top; text-align: right;">60</td> <td style="border-bottom: 0.75pt solid #000000; white-space: nowrap; vertical-align: top;">%</td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 8pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 4%; vertical-align: top; text-align: left;"><sup style="font-size: 75%; vertical-align: top;">1</sup> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 8pt; font-family: times new roman; text-align: left;">BFA may adjust the allocation to equity and fixed-income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations.</div> </td> </tr> </table> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The table shown above depicts only the asset allocation between equity and fixed income investments. The Fund may also invest in Tactical Allocation Underlying Funds, which will not be allocated towards the equity and fixed income percentages listed for the glide path. The Fund’s investment in money market funds and commodity-related instruments also will not be allocated towards the equity and fixed income percentages listed for the glide path. This means that in considering the glide path, you should understand that it is not a complete representation of the Fund’s portfolio. It shows only how the Fund generally allocates assets between equity and fixed income investments as a percentage of the Fund’s net assets, and notwithstanding that it shows figures that add up to 100%, it does not account for the Fund’s investments in other asset classes (which can include Tactical Allocation Underlying Funds, currency exposure, commodity-related instruments or money market funds, as noted above).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Although the asset allocation targets among equity and fixed income assets listed for the glide path (each as a percentage of the Fund’s net assets) are general, long-term targets, BFA may adjust the allocation to equity and fixed income in the Fund, based on an assessment of the current market conditions and the potential contribution of each asset class to the expected risk and return characteristics of the Fund. In general, the adjustments will be limited to +/- 10% relative to the target allocations. BFA may determine, in light of market conditions or other factors, that a greater variation is warranted to protect the Fund or achieve its investment objective. Investments in equity and fixed income Underlying Funds will be allocated towards the equity and fixed income percentages based on their classification.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">BFA’s second step in the structuring of the Fund is the selection of the Underlying Funds, derivatives and commodity-related instruments. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the “Details About the Funds — Information About the Underlying Funds” section of the prospectus for a list of the Underlying Funds, their classification into</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">equity, fixed income, Tactical Allocation or money market funds and a brief description of their investment objectives and primary investment strategies. The specific derivatives selected for the Fund are determined at BFA’s discretion and may change as deemed appropriate to allow the Fund to meet its investment objective.</div> <br/> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Within the prescribed percentage allocations to equity and fixed income, BFA seeks to diversify the Fund. The equity allocation may be further diversified by style (including both value and growth funds and issuers), market capitalization (including large cap, mid cap, small cap and emerging growth funds and issuers), region (including domestic and international (including emerging market) funds and issuers) or other factors. The fixed income allocation may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non‑investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed income are determined at the discretion of the investment team and can be changed to reflect the current market environment.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">The Fund may seek to provide exposure to the investment returns of real assets that trade in the commodity markets through investment in commodity-linked derivative instruments and investment vehicles such as exchange-traded funds that invest exclusively in commodities and are designed to provide this exposure without direct investment in physical commodities. The Fund may also gain exposure to commodity markets by investing up to 25% of its total assets, inclusive of leverage, in [Cayman Subsidiary] (the “[Cayman Subsidiary]”), a wholly owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments. The [Cayman Subsidiary] may also hold cash and invest in other instruments, including fixed income securities, either as investments or to serve as margin or collateral for the [Cayman Subsidiary’s] derivative positions. The [Cayman Subsidiary] (unlike the Fund) may invest without limitation in commodity-related instruments. However, the [Cayman Subsidiary] is otherwise subject to the same fundamental, non‑fundamental and certain other investment restrictions as the Fund.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Prospectuses for each of BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic Retirement Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2030 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2035 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2040 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2045 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2050 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2055 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2060 Fund, BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2065 Fund, and BlackRock LifePath<sup style="font-size: 75%; vertical-align: top;">®</sup> Dynamic 2070 Fund entitled “Fund Overview — Key Facts About [the Fund] — Principal Risks of Investing in the Fund — Principal Risks of the Fund’s Investment Strategies” is amended to add the following:</div> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Commodities Related Investments Risk </span></span>— Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in inflation, interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 5%;"> </td> <td style="width: 3%; vertical-align: top; text-align: left;">•</td> <td style="width: 1%; vertical-align: top;"> </td> <td style="vertical-align: top; text-align: left;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt; text-align: left;"><span style="font-weight: bold;"><span style="font-style: italic;">Subsidiary Risk </span></span>— By investing in the [Cayman Subsidiary], the Fund is indirectly exposed to the risks associated with the [Cayman Subsidiary’s] investments. The commodity-related instruments held by the [Cayman Subsidiary] are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the [Cayman Subsidiary] will be achieved. [Cayman Subsidiary] is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the [Cayman Subsidiary], and the Fund and the [Cayman Subsidiary] are both managed by BlackRock, making it unlikely that the [Cayman Subsidiary] will take action contrary to the interests of the Fund</div> </td> </tr> </table> <table cellpadding="0" cellspacing="0" style="border-collapse: collapse; font-family: times new roman; font-size: 10pt; border-spacing: 0px; width: 100%;"> <tr style="page-break-inside: avoid;"> <td style="width: 9%;"> </td> <td style="vertical-align: top;"> <div style="margin-top: 0pt; margin-bottom: 0pt; font-family: times new roman; font-size: 10pt;">and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the [Cayman Subsidiary], and the Fund’s role as sole shareholder of the [Cayman Subsidiary]. The [Cayman Subsidiary] is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund, except that the [Cayman Subsidiary] may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the [Cayman Subsidiary] to operate as described in this prospectus and the SAI and could adversely affect the Fund.</div> </td> </tr> </table> BLACKROCK FUNDS III 2026-04-30