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margin-top: 0.0pt; text-align: left;">The investment objective of AMG GW&K International Small Cap Fund (the “Fund”) is to seek long-term capital appreciation.</div> Fees and Expenses of the Fund <div style="line-height: 10.9pt; margin-top: 0.00pt; text-align: left;">The table below 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 financial intermediaries, which are not reflected in the tables and examples below.</div> Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment) 0.0069 0.0069 0.0069 0 0 0 0.0084 0.0069 0.0059 0.0153 0.0138 0.0128 -0.0039 -0.0039 -0.0039 0.0114 0.0099 0.0089 October 1, 2027 Expense Example <div style="line-height: 10.9pt; margin-top: -0.01pt; text-align: left;">This Example will help you compare the cost of investing in the Fund to the cost of investing in other mutual funds. The Example makes certain assumptions. It assumes that you invest $10,000 as an initial investment in the Fund for the time periods </div> <div style="line-height: 10.9pt; text-align: left;">indicated and then redeem all of your shares at the end of those periods. It also assumes that your investment has a 5% total return each year and the Fund’s operating expenses remain the same. The first year of each amount shown in the Example reflects the Fund’s contractual expense limitation through October 1, 2027. Although your actual costs may be higher or lower, based on the above assumptions, your costs would be:</div> 116 445 797 1790 101 399 718 1624 91 367 665 1511 Portfolio Turnover <div style="line-height: 10.9pt; margin-top: 0.00pt; text-align: left;">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 Fund 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 31% of the average value of its portfolio.</div> 0.31 Principal Investment Strategies <div style="line-height: 10.9pt; margin-top: 0.00pt; text-align: left;">The Fund seeks to achieve its investment objective by investing primarily in a portfolio of equity securities issued by foreign, small market capitalization companies. The Fund invests in companies that GW&K Investment Management, LLC, the subadviser to the Fund (“GW&K” or the “Subadviser”), believes have the ability to grow earnings or asset value over the long term. Using its fundamental research process, GW&K seeks to identify quality companies trading at attractive prices, often under-researched or under-owned by other institutional investors, and possessing one or more of the following characteristics: </div> <div style="line-height: 10.0pt; margin-left: 26.89pt; margin-top: 0.00pt; text-align: left;">○Stable and visible earnings or cash flow growth with a high-quality business franchise; </div> <div style="line-height: 10.0pt; margin-left: 26.89pt; margin-top: 0.00pt; text-align: left;">○Under-appreciated growth potential trading at a discounted valuation; </div> <div style="line-height: 10.0pt; margin-left: 26.89pt; margin-top: 0.00pt; text-align: left;">○Attractive assets with possible catalysts to unlock embedded value; or </div> <div style="line-height: 10.0pt; margin-left: 26.89pt; margin-top: 0.00pt; text-align: left;">○Potential for rapid growth requiring a longer-term investment horizon to recognize underlying value </div> <div style="margin-top: 6pt;">Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in equity securities of small market capitalization companies. The Fund defines small market capitalization companies as those with a market capitalization of less than $5 billion or otherwise within the capitalization range of companies in the MSCI World ex USA Small Cap Index. As of September 1, 2026, the date of the latest rebalance of the MSCI World ex USA </div> <div style="line-height: 10.9pt; text-align: left;">Small Cap Index, the capitalization range was $200.11 million to $12.074 billion. Index capitalization ranges will change over time. </div> <div style="margin-top: 6pt;">Additionally, under normal circumstances, the Fund invests at least 40% (or, if market conditions are not favorable in the view of GW&K, at least 30%) of its net assets in investments economically tied to countries other than the U.S., and the Fund will hold investments economically tied to a minimum of three countries other than the U.S. The Fund considers an investment to be economically tied to a country other than the U.S. if it provides investment exposure to a non-U.S. issuer. The Fund considers a company to be non-U.S. issuer if (i) it is organized outside the U.S. or maintains a principal place of business outside the U.S., (ii) its securities are traded principally outside the U.S., or (iii) during its most recent fiscal year, it derived at least 50% of its revenues or profits from goods produced or sold, investments made, or services performed outside the U.S. or it has at least 50% of its assets outside the U.S. The Fund may invest in securities of issuers located in any country outside the U.S., including developed and emerging market countries. </div> <div style="margin-top: 6pt;">The Fund’s investments in equity securities may include common shares and other equity securities, such as preferred shares, depositary receipts and securities convertible into common shares, preferred shares or depositary receipts, and pooled investment vehicles, including real estate investment trusts (“REITs”).</div> Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in equity securities of small market capitalization companies. The Fund defines small market capitalization companies as those with a market capitalization of less than $5 billion or otherwise within the capitalization range of companies in the MSCI World ex USA Small Cap Index. As of September1, 2026, the date of the latest rebalance of the MSCI World ex USA <div style="line-height: 10.9pt; text-align: left;">Small Cap Index, the capitalization range was $200.11 million to $12.074 billion. Index capitalization ranges will change over time. </div> The Fund considers an investment to be economically tied to a country other than the U.S. if it provides investment exposure to a non-U.S. issuer. The Fund considers a company to be non-U.S. issuer if (i) it is organized outside the U.S. or maintains a principal place of business outside the U.S., (ii) its securities are traded principally outside the U.S., or (iii) during its most recent fiscal year, it derived at least 50% of its revenues or profits from goods produced or sold, investments made, or services performed outside the U.S. or it has at least 50% of its assets outside the U.S. There is the risk that you may lose money on your investment. An investment in the Fund is not a deposit or obligation of any bank, is not endorsed or guaranteed by any bank, and is not insured by the Federal Deposit Insurance Corporation (“FDIC”) or any other government agency. <div style="margin-top: 6pt;">Market Risk—market prices of investments held by the Fund may fall rapidly or unpredictably due to a variety of factors, including economic or market conditions, or other factors including terrorism, war, natural disasters and the spread of infectious illness or other public health issues, including epidemics or pandemics, or in response to events that affect particular industries or companies. In addition, unexpected political, regulatory, trade and diplomatic events within the United States and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy, perhaps suddenly and to a significant degree.</div> <div style="margin-top: 6pt;">Foreign Investment Risk—investments in foreign issuers involve additional risks (such as risks arising from less frequent trading, changes in political or social conditions, and less </div> <div style="line-height: 10.9pt; text-align: left;">publicly available information about non-U.S. issuers) that differ from those associated with investments in U.S. issuers and may result in greater price volatility.</div> <div style="margin-top: 6pt;">Small-Capitalization Stock Risk—the stocks of small-capitalization companies often have greater price volatility, lower trading volume, and less liquidity than the stocks of larger, more established companies.</div> <div style="margin-top: 6pt;">Growth Stock Risk—the prices of equity securities of companies that are expected to experience relatively rapid earnings growth, or “growth stocks,” may be more sensitive to market movements because the prices tend to reflect future investor expectations rather than just current profits.</div> <div style="margin-top: 6pt;">Emerging Markets Risk—investments in emerging markets are subject to the general risks of foreign investments, as well as additional risks which can result in greater price volatility. Such additional risks include the risk that markets in emerging market countries are typically less developed and less liquid than markets in developed countries and such markets are subjected to increased economic, political, or regulatory uncertainties.</div> <div style="margin-top: 6pt;">Currency Risk—fluctuations in exchange rates may affect the total loss or gain on a non-U.S. dollar investment when converted back to U.S. dollars and exposure to non-U.S. currencies may subject the Fund to the risk that those currencies will decline in value relative to the U.S. dollar.</div> <div style="margin-top: 6pt;">Geographic Focus Risk—to the extent the Fund focuses its investments in a particular country, group of countries or geographic region, the Fund is particularly susceptible to economic, political, regulatory or other events or conditions affecting such countries or region, and the Fund’s NAV may be more volatile than the NAV of a more geographically diversified fund and may result in losses. </div> <div style="margin-top: 6pt;">Japan. The Fund is highly susceptible to the social, political, economic, regulatory and other conditions or events that may affect Japan’s economy. The Japanese economy is heavily dependent upon international trade, and, therefore, is particularly exposed to the risks of currency fluctuation, foreign trade policy and regional and global economic disruption, including the risk of increased tariffs, embargoes, and other trade limitations or factors. The Japanese economy, at times, has been impacted by government regulation, intervention, and protectionism; cross-ownership among major corporations; an aging demographic; and a declining population. The potential for natural disasters, such as earthquakes, volcanic eruptions, typhoons and tsunamis, could also have significant negative effects on Japan’s economy.</div> <div style="margin-top: 6pt;">Liquidity Risk—the Fund may not be able to dispose of particular investments, such as illiquid securities, readily at favorable times or prices or the Fund may have to sell them at a loss.</div> <div style="margin-top: 6pt;">Management Risk—because the Fund is an actively managed investment portfolio, security selection or focus on securities in a particular style, market sector or group of companies may cause the Fund to incur losses or underperform relative to its benchmarks or other funds with a similar investment objective. There can be no guarantee that the Subadviser’s investment techniques and risk analysis will produce the desired result.</div> <div style="line-height: 10.9pt; text-align: left;">Political Risk—changes in the general political and social environment of a country can have substantial effects on the value of investments exposed to that country.</div> <div style="margin-top: 6pt;">Real Estate Industry Risk—investments in the Fund may be subject to many of the same risks as a direct investment in real estate. The stock prices of companies in the real estate industry, including REITs, are typically sensitive to changes in real estate values, property taxes, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use, and rents, as well as the management skill and creditworthiness of the issuer. Investments in the real estate sector also may be adversely impacted by natural or environmental disasters. REITs also depend generally on their ability to generate cash flow to make distributions to shareholders or unitholders and are subject to the risk of failing to qualify for favorable tax treatment under the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”).</div> <div style="margin-top: 6pt;">Sector Risk—issuers and companies that are in similar industry sectors may be similarly affected by particular economic or market events; to the extent the Fund has substantial holdings within a particular sector, the risks associated with that sector increase. Stocks in the industrials sector may comprise a significant portion of the Fund’s portfolio. The industrials sector may be affected by general economic trends, including employment, economic growth and interest rates, changes in consumer confidence and spending, government regulation, commodity prices and competitive pressures.</div> <div style="margin-top: 6pt;">Value Stock Risk—value stocks may perform differently from the market as a whole and may be undervalued by the market for a long period of time.</div> Performance <div style="line-height: 10.9pt; margin-top: 0.00pt; text-align: left;">The following performance information illustrates the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s performance compares to that of (i) a broad based index and (ii) an additional index reflecting the market segment(s) in which the Fund invests. As always, past performance of the Fund (before and after taxes) is not an indication of how the Fund will perform in the future. </div> <div style="margin-top: 6pt;">As of October 8, 2020, GW&K was appointed as subadviser to the Fund and the Fund changed its name to “AMG GW&K International Small Cap Fund,” adopted its current investment strategies and began comparing its performance to the MSCI World ex USA Small Cap Index. The Fund’s performance information for periods prior to October 8, 2020 reflects the Fund’s investment strategy that was in effect at that time and would have been different had the Fund’s current investment strategy been in effect. </div> <div style="margin-top: 6pt;">Effective February 27, 2017, outstanding Class S shares of the Fund (formerly Service Class shares, which were renamed Class S shares on October 1, 2016) were renamed Class N shares. Effective October 1, 2016, outstanding Institutional Class shares of the Fund were renamed Class I shares. </div> <div style="margin-top: 6pt;">To obtain updated performance information for the Fund please visit wealth.amg.com or call 800.548.4539.</div> The following performance information illustrates the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s performance compares to that of (i) a broad based index and (ii) an additional index reflecting the market segment(s) in which the Fund invests. As always, past performance of the Fund (before and after taxes) is not an indication of how the Fund will perform in the future. wealth.amg.com 800.548.4539 Calendar Year Total Returns as of 12/31/25 (Class N) <div style="margin-top: 9pt;">Best Quarter: 20.61% (2nd Quarter 2020) Worst Quarter: -30.82% (1st Quarter 2020)</div> <div style="margin-top: 9pt;">Year-to-Date (as of 6/30/26): 6.27%</div> Best Quarter: 0.2061 2020-06-30 Worst Quarter: -0.3082 2020-03-31 Year-to-Date 2026-06-30 0.0627 Average Annual Total Returns as of 12/31/25 0.2064 0.0118 0.0539 0.1947 0.0090 0.0500 0.1284 0.0100 0.0433 0.2081 0.0134 0.0555 0.2096 0.0144 0.0342 0.3185 0.0946 0.0855 0.0815 0.3407 0.0649 0.0805 0.0713 2017-05-31 2017-05-31 2017-05-31 <div style="margin-top: 6pt;">After-tax returns are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”). After-tax returns are shown for Class N shares only, and after-tax returns for Class I and Class Z shares will vary.</div> After-tax returns are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”). After-tax returns are shown for Class N shares only, and after-tax returns for Class I and Class Z shares will vary. AMG Funds LLC (the “Investment Manager”) has contractually agreed, through at least October 1, 2027, to waive management fees and/or pay or reimburse the Fund’s expenses in order to limit Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements (exclusive of taxes, interest (including interest incurred in connection with bank and custody overdrafts and in connection with securities sold short), shareholder servicing fees, distribution and service (12b-1) fees, brokerage commissions and other transaction costs, dividends payable with respect to securities sold short, acquired fund fees and expenses, and extraordinary expenses) of the Fund to the annual rate of 0.89% of the Fund’s average daily net assets (this annual rate or such other annual rate that may be in effect from time to time, the “Expense Cap”), subject to later reimbursement by the Fund in certain circumstances. In general, for a period of up to 36 months after the date any amounts are paid, waived or reimbursed by the Investment Manager, the Investment Manager may recover such amounts from the Fund, provided that such repayment would not cause the Fund’s Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements (exclusive of the items noted in the parenthetical above) to exceed either (i) the Expense Cap in effect at the time such amounts were paid, waived or reimbursed, or (ii) the Expense Cap in effect at the time of such repayment by the Fund. The contractual expense limitation may only be terminated in the event the Investment Manager or a successor ceases to be the investment manager of the Fund or a successor fund, by mutual agreement between the Investment Manager and the AMG Funds III Board of Trustees or in the event of the Fund’s liquidation unless the Fund is reorganized or is a party to a merger in which the surviving entity is successor to the accounting and performance information of the Fund. Class Z and Index performance shown reflects performance since the inception date of the Fund's Class Z shares on May 31, 2017.