iShares Short-Term TIPS Bond Index Fund

APRIL 30, 2026

Summary Prospectus

BlackRock FundsSM | Investor A and Institutional Shares

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iShares Short-Term TIPS Bond Index Fund

Investor A: BAIPX • Institutional: BIIPX

Before you invest, you may want to review the Fund’s prospectus, which contains more information about the Fund and its risks. You can find the Fund’s prospectus (including amendments and supplements), reports to shareholders and other information about the Fund, including the Fund’s statement of additional information, online at https://www.blackrock.com/prospectus. You can also get this information at no cost by calling (800) 441-7762 or by sending an e-mail request to prospectus.request@blackrock.com, or from your financial professional. The Fund’s prospectus and statement of additional information, both dated April 30, 2026, as amended and supplemented from time to time, are incorporated by reference into (legally made a part of) this Summary Prospectus.

This Summary Prospectus contains information you should know before investing, including information about risks. Please read it before you invest and keep it for future reference.

The Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this Summary Prospectus. Any representation to the contrary is a criminal offense.

Not FDIC Insured ● May Lose Value ● No Bank Guarantee

Summary Prospectus

Key Facts About iShares Short-Term TIPS Bond Index Fund

Investment Objective

The investment objective of iShares Short-Term TIPS Bond Index Fund (the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to seek to track the investment results of an index composed of U.S. 0-5 Year Treasury Inflation-Protected Securities (“TIPS”).

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to your financial professional or your selected securities dealer, broker, investment adviser, service provider or industry professional (including BlackRock Advisors, LLC (“BlackRock”) and its affiliates) (each, a “Financial Intermediary”), which are not reflected in the table and example below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)	Investor A Shares	Institutional Shares
Management Fee1	0.01 %	0.01 %
Distribution and/or Service (12b-1) Fees	0.25 %	None
Other Expenses	0.13 %	0.06 %
Total Annual Fund Operating Expenses	0.39 %	0.07 %
Fee Waivers and/or Expense Reimbursements1,2	(0.03 )%	—
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements1,2	0.36 %	0.07 %

As described in the “Management of the Fund” section of the Fund’s prospectus beginning on page 33, BlackRock has contractually agreed to waive the management fee with respect to any portion of the Fund’s assets estimated to be attributable to investments in other equity and fixed-income mutual funds and exchange-traded funds managed by BlackRock or its affiliates that have a contractual management fee, through June 30, 2027. In addition, BlackRock has contractually agreed to waive its management fees by the amount of investment advisory fees the Fund pays to BlackRock indirectly through its investment in money market funds managed by BlackRock or its affiliates, through June 30, 2027. The contractual agreements may be terminated upon 90 days’ notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

As described in the “Management of the Fund” section of the Fund’s prospectus beginning on page 33, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 0.36% (for Investor A Shares) and 0.11% (for Institutional Shares) of average daily net assets through June 30, 2027. The contractual agreement may be terminated upon 90 days’ notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

	1 Year	3 Years	5 Years	10 Years
Investor A Shares	$37	$122	$216	$490
Institutional Shares	$7	$23	$40	$90

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 12% of the average value of its portfolio.

Principal Investment Strategies of the Fund

The Fund seeks to track the investment results of the Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index (Series-L) (the “Underlying Index”), which measures the performance of inflation-protected public obligations of the U.S. Treasury that have a remaining maturity of less than five years. Inflation-protected public obligations of the U.S. Treasury, commonly known as “TIPS,” are securities issued by the U.S. Treasury that are designed to provide inflation protection to investors. TIPS are income-generating instruments whose interest and principal payments are adjusted for inflation — a sustained increase in prices that erodes the purchasing power of money. The inflation adjustment, which is typically applied monthly to the principal of the bond, follows a designated inflation index, the consumer price index (“CPI”), and TIPS’ principal payments are adjusted according to changes in the CPI. A fixed coupon rate is applied to the inflation-adjusted principal so that as inflation rises, both the principal value and the interest payments increase. This can provide investors with a hedge against inflation, as it helps preserve the purchasing power of an investment. Because of this inflation adjustment feature, inflation-protected bonds typically have lower yields than conventional fixed-rate bonds. If there is deflation, the principal value of an inflation-linked security will be adjusted downward, and consequently the interest payments (calculated with respect to a smaller principal amount) will be reduced. During periods of deflation, low inflation or no inflation, a conventional bond may perform better than inflation-linked securities.

The Underlying Index includes all publicly-issued U.S. Treasury inflation-protected securities that have less than five years remaining to maturity, are rated investment-grade and have $250 million or more of outstanding face value. In addition, the securities in the Underlying Index must be denominated in U.S. dollars and have a notional coupon that is fixed-rate or zero. The Underlying Index is market capitalization-weighted and the securities in the Underlying Index are updated on the last calendar day of each month.

BlackRock uses a representative sampling indexing strategy to manage the Fund. “Representative sampling” is an indexing strategy that involves investing in a representative sample of securities that collectively has an investment profile similar to that of the Underlying Index. The securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities in the Underlying Index.

The Fund generally invests at least 90% of its assets, plus the amount of any borrowing for investment purposes, in securities of the Underlying Index. From time to time when conditions warrant, however, the Fund may invest at least 80% of its assets in securities of the Underlying Index. The Fund may invest a portion of the remainder of its assets in securities not included in the Underlying Index, but which BlackRock believes will help the Fund track the Underlying Index.

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other Government agency. The following is a summary description of the principal risks of investing in the Fund. The relative significance of each risk factor below may change over time and you should review each risk factor carefully.

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TIPS Risk —The interest rate on TIPS is fixed at issuance, but over the life of the bond this interest may be paid on an increasing or decreasing principal value that has been adjusted for inflation. Although repayment of the original bond principal upon maturity is guaranteed, the market value of TIPS is not guaranteed, and will fluctuate.

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U.S. Treasury Obligations Risk — U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s U.S. Treasury obligations to decline.

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Inflation-Indexed Bonds Risk — The principal value of an investment in the Fund is not protected or otherwise guaranteed by virtue of any investments by the Fund in inflation-indexed bonds. The value of inflation-indexed securities generally fluctuates with changes in real interest rates, decreasing when real interest rates rise and increasing when real interest rates fall. Real interest rates represent nominal (or stated) interest rates minus the inflation rates. If the Fund purchases TIPS in the secondary market and the bonds’ principal values previously were adjusted upward, but then there is a period of declining inflation rates, the Fund may receive at maturity less than it invested.

In addition, interest payments on inflation-indexed securities generally vary up or down along with the rate of inflation, and inflation-indexed bonds typically have lower nominal yields than conventional fixed-rate bonds. If the index measuring inflation falls, the principal value of inflation-indexed bonds will be adjusted downward, and consequently the interest payable on these securities (calculated with respect to a smaller principal amount) will be reduced.

Any increase in the principal amount of an inflation-indexed bond will be considered taxable ordinary income, even though investors do not receive their principal until maturity. Periodic adjustments for inflation to the principal amount of an inflation-indexed bond may give rise to original issue discount, which will be includable in the Fund’s gross income. Due to original issue discount, the Fund may be required to make annual distributions to shareholders that exceed the cash received, which may cause the Fund to liquidate certain investments when it is not advantageous to do so. Also, if the principal value of an inflation-indexed bond is adjusted downward due to deflation, amounts previously distributed in the taxable year may be characterized in some circumstances as a return of capital.

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Index-Related Risk — The index provider may rely on various sources of information to assess the criteria of components of the Underlying Index, including information that may be based on assumptions and estimates. Neither the Fund nor BlackRock can offer assurances that the index provider’s methodology or sources of information will provide an accurate assessment of included components. Errors in index data, index computations or the construction of the Underlying Index in accordance with its methodology may occur, and the index provider may not identify or correct them promptly or at all, which may have an adverse impact on the Fund and its shareholders. Unusual market conditions or other unforeseen circumstances (such as natural disasters, political unrest or war) may impact the index provider or a third-party data provider and could cause the index provider to postpone a scheduled rebalance. This could cause the Underlying Index to vary from its normal or expected composition.

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Passive Investment Risk — Because BlackRock does not select individual companies in the index that the Fund tracks, the Fund may hold securities of companies that present risks that an investment adviser researching individual securities might seek to avoid.

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Tracking Error Risk — The Fund is subject to the risk of “tracking error,” which is the divergence of the Fund’s performance from that of the Underlying Index. Tracking error may occur due to a number of factors, including differences between the securities and other assets held in the Fund’s portfolio and those included in the Underlying Index; differences in the timing and methodologies used to value securities and other assets; transaction costs and other expenses incurred by the Fund that the Underlying Index does not incur; the Fund’s holding of uninvested cash; differences in the timing of the accrual or the valuation of dividends or interest received by the Fund or distributions paid to Fund shareholders; tax gains or losses; differences between the amount and/or timing of withholding taxes on dividends reflected in the Underlying Index from the Fund’s obligation, if any, for foreign withholding taxes; the requirements for the Fund to maintain pass-through tax treatment; portfolio transactions carried out to minimize the distribution of capital gains to shareholders; changes to the Underlying Index, such as during a rebalancing or reconstitution; and impacts to the Fund of complying with certain regulatory requirements or limits. A fund that tracks an index composed of a large number of securities or other assets may experience greater tracking error than a fund that tracks a more narrow index. Tracking error risk may be heightened during times of increased market volatility or other unusual market conditions.

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Representative Sampling Risk — Representative sampling is a method of indexing that involves investing in a representative sample of securities that collectively have a similar investment profile to the Underlying Index and resemble the Underlying Index in terms of risk factors and other key characteristics. The Fund may or may not hold every security in the Underlying Index. When the Fund deviates from a full replication indexing strategy to utilize a representative sampling strategy, the Fund is subject to an increased risk of tracking error, in that the securities selected in the aggregate for the Fund may not have an investment profile similar to those of the Underlying Index.

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Asset Class Risk — The securities and other assets or financial instruments in the Underlying Index or in the Fund’s portfolio may underperform in comparison to financial markets generally, a particular financial market, another index, or other asset classes.

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Income Risk — The Fund’s income may decline due to a decline in inflation, deflation or changes in inflation expectations.

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Interest Rate Risk — Interest rate risk refers to the risk of fluctuations in the value of a fixed-income security due to changes in the general level of interest rates. Interest rate changes can be sudden and unpredictable and are influenced by a number of factors, including government policy, monetary policy, inflation expectations, perceptions of risk, and supply and demand for fixed-income securities. An increase in interest rates generally will cause the value of fixed-income securities to decline. Securities with longer maturities generally are more sensitive to interest rate changes and subject to greater fluctuations in value. Changes in interest rates may have unpredictable effects

on fixed-income markets and result in heightened volatility and lower liquidity for certain instruments, which may adversely affect the Fund’s performance. During periods of very low or negative interest rates, the Fund may be unable to maintain positive returns or pay dividends to shareholders.

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Issuer Risk — Fund performance depends on the performance of individual securities to which the Fund has exposure. Changes in the financial condition or credit rating of an issuer of those securities may cause the value of the securities to decline.

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Management Risk — As the Fund may not fully replicate the Underlying Index, it is subject to the risk that BlackRock’s investment strategy may not produce the intended results.

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Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. The value of a security or other asset may decline due to changes in general market conditions, economic trends or events that are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its investments. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

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Operational and Technology Risks — The Fund is directly and indirectly susceptible to operational and technology risks, including those related to human errors, processing errors, communication errors, systems failures, cybersecurity incidents, and the use of artificial intelligence and machine learning (“AI”), which may result in losses for the Fund and its shareholders or may impair the Fund’s operations. While the Fund’s service providers are required to have appropriate operational, information security and cybersecurity risk management policies and procedures, their methods of risk management may differ from those of the Fund. Operational and technology risks for the issuers in which the Fund invests could also result in material adverse consequences for such issuers and may cause the Fund’s investments in such issuers to lose value.

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Risk of Investing in the United States — Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.

Performance Information

The information shows you how the Fund’s performance has varied for the periods since inception and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the ICE BofA U.S. Broad Market Index and the Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index (Series-L). The Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index (Series L) is relevant to the Fund because it has characteristics similar to the Fund’s investment strategies. To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. The table includes all applicable fees. If the Fund’s investment manager and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance, including its current net asset value, can be obtained by visiting http://www.blackrock.com or can be obtained by phone at (800) 882-0052.

Investor A Shares
ANNUAL TOTAL RETURNS
iShares Short-Term TIPS Bond Index Fund
As of 12/31

During the periods shown in the bar chart, the highest return for a quarter was 2.98% (quarter ended March 31, 2025) and the lowest return for a quarter was -2.76% (quarter ended September 30, 2022).

For the periods ended 12/31/25 Average Annual Total Returns	1 Year	5 Years	Since Inception (February 16, 2016)
iShares Short-Term TIPS Bond Index Fund — Investor A Shares
Return Before Taxes	5.73 %	3.18 %	2.83 %
Return After Taxes on Distributions	3.88 %	1.37 %	1.55 %
Return After Taxes on Distributions and Sale of Fund Shares	3.38 %	1.64 %	1.61 %
iShares Short-Term TIPS Bond Index Fund — Institutional Shares
Return Before Taxes	6.02 %	3.45 %	3.11 %
ICE BofA U.S. Broad Market Index (Reflects no deduction for fees, expenses or taxes)	7.15 %	(0.42 )%	1.84 %
Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index (Series-L) (Reflects no deduction for fees, expenses or taxes)	6.07 %	3.54 %	3.20 %

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Institutional Shares will vary.

Investment Manager

The Fund’s investment manager is BlackRock Advisors, LLC (previously defined as “BlackRock”). The Fund’s sub-adviser is BlackRock Fund Advisors (the “Sub-Adviser”). Where applicable, the use of the term “BlackRock” also refers to the Sub-Adviser.

Portfolio Managers

Portfolio Manager	Portfolio Manager of the Fund Since	Title
James Mauro	2016	Managing Director of BlackRock, Inc.
Jonathan Graves	2025	Managing Director of BlackRock, Inc.
Marcus Tom	2025	Director of BlackRock, Inc.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund each day the New York Stock Exchange is open. To purchase or sell shares, you should contact your Financial Intermediary, or, if you hold your shares through the Fund, you should contact the Fund by phone at (800) 441-7762, by mail (c/o BlackRock Funds, P.O. Box 534429, Pittsburgh, Pennsylvania 15253-4429) or by the Internet at www.blackrock.com. The Fund’s initial and subsequent investment minimums generally are as follows, although the Fund may reduce or waive the minimums in some cases:

	Investor A Shares	Institutional Shares
Minimum Initial Investment	$1,000 for all accounts except: •$50, if establishing an Automatic Investment Plan. •There is no investment minimum for employer- sponsored retirement plans (not including SEP IRAs, SIMPLE IRAs or SARSEPs). •There is no investment minimum for certain fee- based programs.	There is no minimum initial investment for: •Employer-sponsored retirement plans (not including SEP IRAs, SIMPLE IRAs or SARSEPs), state sponsored 529 college savings plans, collective trust funds, investment companies or other pooled investment vehicles, unaffiliated thrifts and unaffiliated banks and trust companies, each of which may purchase shares of the Fund through a Financial Intermediary that has entered into an agreement with the Fund’s distributor to purchase such shares. •Clients of Financial Intermediaries that: (i) charge such clients a fee for advisory, investment consulting, or similar services or (ii) have entered into an agreement with the Fund’s distributor to offer Institutional Shares through a no-load program or investment platform. •Clients investing through a self-directed IRA brokerage account program sponsored by a retirement plan record-keeper, provided that such program offers only mutual fund options and that the program maintains an account with the Fund on an omnibus basis. $2 million for individuals and “Institutional Investors,” which include, but are not limited to, endowments, foundations, family offices, local, city, and state governmental institutions, corporations and insurance company separate accounts who may purchase shares of the Fund through a Financial Intermediary that has entered into an agreement with the Fund’s distributor to purchase such shares. $1,000 for: •Clients investing through Financial Intermediaries that offer such shares on a platform that charges a transaction based sales commission outside of the Fund. •Tax-qualified accounts for insurance agents that are registered representatives of an insurance company’s broker-dealer that has entered into an agreement with the Fund’s distributor to offer Institutional Shares, and the family members of such persons.
Minimum Additional Investment	$50 for all accounts (with the exception of certain employer-sponsored retirement plans which may have a lower minimum).	No subsequent minimum.