Summary Prospectus by Investment Company (Form 497K)

 

	Summary Prospectus	May 1, 2025 (As revised October 21, 2025)
	AMG GW&K ESG Bond Fund

 

Class N: MGFIX

Class I: MGBIX

Investment Objective

AMG GW&K ESG Bond Fund's (the "Fund") investment objective is to generate income and capital appreciation.

Fees and Expenses of the Fund

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.

Annual Fund Operating Expenses
(expenses that you pay each year as a percentage of the value of your investment)

 

	Class N	Class I
Management Fee	0.23 %	0.23 %
Distribution and Service (12b-1) Fees	None	None
Other Expenses	0.50 %	0.30 %
Total Annual Fund Operating Expenses	0.73 %	0.53 %
Fee Waiver and Expense Reimbursements1	(0.05)%	(0.05)%
Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements1	0.68 %	0.48 %

1AMG Funds LLC (the "Investment Manager") has contractually agreed, through at least May 1, 2026, 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 0.43% 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.

Expense Example

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 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 May 1, 2026. Although your actual costs may be higher or lower, based on the above assumptions, your costs would be:

 

	1 Year	3 Years	5 Years	10 Years
Class N	$69	$228	$401	$902
Class I	$49	$165	$291	$660

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 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 37% of the average value of its portfolio.

Principal Investment Strategies

The Fund seeks to achieve its objective by investing in a diversified portfolio of fixed income securities.

Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in bonds (debt securities). The term "bond" includes any debt or fixed income securities. Up to 30% of the Fund's assets may be invested in below investment grade securities (commonly known as "junk bonds" or "high yield securities"). Below investment grade securities are rated below Baa3 by Moody's Investors Service, Inc. ("Moody's") or below BBB- by S&P Global Ratings ("S&P") or similarly rated by another nationally recognized statistical rating organization, or unrated but determined by GW&K Investment Management, LLC, the subadviser to the Fund ("GW&K" or the "Subadviser"), to be of comparable credit quality. In cases where the credit ratings agencies have assigned different credit ratings to the same security, the security will be considered to have the higher credit rating. The Fund may continue to hold securities that are

downgraded in credit rating subsequent to their purchase if GW&K believes it would be advantageous to do so. While the Fund may purchase debt securities of any duration, the Fund currently intends to primarily invest in debt securities so that the overall duration of the Fund's portfolio will remain +/- 20% of the duration of its benchmark, the Bloomberg U.S. Aggregate Bond Index. As of February 28, 2025, the duration of the benchmark was 6.10 years. The average duration of debt securities in the Fund's portfolio may, however, be shorter or longer depending on market conditions.

The Fund may invest in debt securities issued by any of the following: public and private U.S. and non-U.S. companies; the U.S. government and its agencies, such as the Federal Home Loan Bank; state and local governments issuing taxable municipal securities; and governments, government agencies, authorities or instrumentalities and supra-national organizations in foreign countries, including emerging markets. The Fund may also invest in asset-backed and mortgage-backed debt securities. The Fund may invest in exchange-traded funds ("ETFs") to gain exposure to certain bond sectors such as bank loans. The Fund may also invest in Treasury Inflation Protected Securities ("TIPS") and preferred securities. Up to 10% of the Fund's assets may be invested in non-U.S. dollar-denominated instruments, including sovereign and corporate bonds. The Fund may also invest in bonds whose proceeds are reserved for financing the implementation of the United Nations' Sustainable Development Goals or other sustainable projects. GW&K's investment process involves fundamental credit research and GW&K's analysis of how the Fund's potential investments are affected by material environmental, social and governance ("ESG") factors. In selecting potential investments for the Fund, GW&K uses top-down research that focuses on managing duration, yield curve, credit quality, volatility and liquidity, as well as bottom-up research that focuses on fundamental analysis, valuation analysis, technical analysis, and ESG factor analysis. GW&K may adjust its assessment of an investment based on a number of considerations.

GW&K applies its ESG factor analysis as one element of the investment process when selecting debt securities issued by public and private companies, including corporate bonds and preferred securities, state and local governments issuing taxable municipal securities, and bonds whose proceeds are reserved for financing the implementation of the United Nations' Sustainable Development Goals or other sustainable projects, but not when selecting debt securities issued by other types of issuers, including but not limited to asset-backed and mortgage-backed debt securities, ETFs, TIPS, non-U.S. dollar-dominated instruments, and securities issued by the U.S. government and its agencies, such as the Federal Home Loan Bank, and governments, government agencies, authorities or instrumentalities and supra-national organizations in foreign countries. GW&K has created its own proprietary ESG Scoring System, which takes into consideration a range of factors, including independent analysis from third parties such as MSCI Inc. and Sustainalytics, as well as its own analysis of material ESG factors. Each of GW&K's sector specialists generally assesses the materiality of relevant environmental, social and governance metrics to bond issues during the fundamental research process, depending on

the sector and for corporate issuers the nature of the company's business. GW&K uses standards developed by the Sustainable Accounting Standards Board to inform these assessments. Environmental assessment may take into account issues such as carbon emissions, natural resource usage, hazardous waste, chemical safety, water stress and sustainable technology. Social assessment may take into account issues such as human rights, labor relations, employee safety, product safety, data security and community relations. Governance assessment may take into account issues such as business ethics, board quality, board composition, compensation practices, financial reporting and stakeholder governance.

GW&K recognizes that the relative impact of ESG factors on investment performance may vary across market sector, industries and regions, but the firm believes that responsible corporate behavior with respect to ESG factors can contribute to positive and sustainable long-term financial performance. GW&K seeks to identify issuers that GW&K believes are leaders in their industries in effectively addressing exposure to ESG risks through business practices, policies and programs, or issuers within an industry that have more limited exposure to ESG risks. The goal of the ESG factor analysis is to seek investments with lesser exposure to, or better management of, ESG risks.

Principal Risks

There is the risk that you may lose money on your investment. All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. 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.

Below are some of the risks of investing in the Fund. The risks are presented in an order intended to facilitate readability and their order does not imply that the realization of one risk is more likely to occur than another risk or likely to have a greater adverse impact than another risk. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund's portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Debt Securities Risk-the value of a debt security changes in response to various factors, including, for example, market-related factors, such as changes in interest rates or changes in the actual or perceived ability of an issuer to meet its obligations. Investments in debt securities are subject to, among other risks, credit risk, interest rate risk, extension risk, prepayment risk and liquidity risk.

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

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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.

Interest Rate Risk-fixed coupon payments (cash flows) of bonds and debt securities may become less competitive with the market in periods of rising interest rates and cause bond prices to decline. During periods of increasing interest rates, the Fund may experience high levels of volatility and shareholder redemptions, and may have to sell securities at times when it would otherwise not do so, and at unfavorable prices, which could reduce the returns of the Fund.

Credit Risk-the issuer of bonds or other debt securities may be unable or unwilling, or may be perceived as unable or unwilling, to make timely interest or principal payments or otherwise honor its obligations. Changes in an issuer's financial strength, credit rating or the market's perception of an issuer's creditworthiness may also affect the value of the Fund's investment in that issuer.

High Yield Risk-below investment grade debt securities and unrated securities of similar credit quality (commonly known as "junk bonds" or "high yield securities") may be subject to greater levels of interest rate, credit, liquidity, and market risk than higher-rated securities. These securities are considered predominately speculative with respect to the issuer's continuing ability to make principal and interest payments.

ESG Investing Risk-because applying the Fund's ESG investment criteria may result in the selection or exclusion of securities of certain issuers for reasons other than financial performance, the Fund's investment returns may underperform funds that do not incorporate ESG factors into their investment process. The incorporation of ESG criteria into the investment process may affect the Fund's investment exposure to certain companies, sectors, regions, countries or types of investments, which could negatively impact the Fund's performance depending on whether such investments are in or out of favor. Applying ESG criteria to investment decisions is qualitative and subjective by nature, and there is no guarantee that the criteria utilized by the Subadviser or any judgment exercised by the Subadviser will improve the financial performance of the Fund or reflect the beliefs or values of any particular investor. ESG standards differ by region and industry, and a company's ESG practices or the Subadviser's assessment of a company's ESG practices may change over time. The Subadviser's evaluation of a company also may be dependent on the availability of timely, complete and accurate ESG data reported by issuers and/or third party data providers. Different methodologies may be used by the various issuers and third party sources that provide ESG data, and such ESG data often lacks standardization, consistency and transparency.

Asset-Backed and Mortgage-Backed Securities Risk-investments in asset-backed and mortgage-backed securities involve risk of severe credit downgrades, loss due to prepayments that occur earlier or later than expected, illiquidity and default.

Changing Distribution Level Risk-the Fund will normally receive income which may include interest, dividends and/or capital gains, depending upon its investments. The distribution amount paid by the Fund will vary and generally depends on the amount of income the Fund earns (less expenses) on its portfolio holdings, and capital gains or losses it recognizes. A decline in the Fund's income or net capital gains arising from its investments may reduce its distribution level.

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.

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.

Exchange-Traded Fund Risk-because exchange-traded funds incur their own costs, investing in them could result in a higher cost to the investor.

Extension Risk-during periods of rising interest rates, a debtor may pay back a bond or other fixed income security slower than expected or required, and the value of such security may fall.

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 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.

Inflation/Deflation Risk-inflation risk is the risk that the value of assets or income from investments will be worth less in the future. Inflation rates may change frequently and drastically as a result of various factors and the Fund's investments may not keep pace with inflation, which may result in losses to Fund investors or adversely affect the real value of shareholders' investments in the Fund. As inflation rates increase, fixed income securities markets may experience heightened levels of interest rate volatility and liquidity risk. Deflation risk is the risk that the prices throughout the economy decline over time - the opposite of inflation. Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of the Fund's portfolio.

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.

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

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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.

Municipal Market Risk-factors unique to the municipal bond market may negatively affect the value of municipal bonds. These factors include political or legislative changes, and uncertainties related to the tax status of the securities and the rights of investors in the securities. The Fund may invest in a group of municipal obligations that are related in such a way that an economic, business, or political development affecting one would also affect the others.

Prepayment Risk-a debtor may exercise its right to pay back a bond or other debt security earlier than expected or required during periods of decreasing interest rates.

Reinvestment Risk-the Fund may have difficulty reinvesting payments from debtors and may receive lower rates than from its original investments.

U.S. Government Securities Risk-obligations issued by some U.S. Government agencies, authorities, instrumentalities, or sponsored enterprises such as Government National Mortgage Association ("GNMA") are backed by the full faith and credit of the U.S. Government, while obligations issued by others, such as Federal National Mortgage Association ("FNMA"), Federal Home Loan Mortgage Corporation ("FHLMC"), and Federal Home Loan Banks ("FHLBs"), are not backed by the full faith and credit of the U.S. Government and are backed solely by the entity's own resources or by the ability of the entity to borrow from the U.S. Treasury. If one of these agencies defaults on a loan, there is no guarantee that the U.S. Government will provide financial support.

Performance

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 a broad-based securities market index. As always, past performance of the Fund (before and after taxes) is not an indication of how the Fund will perform in the future.

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.

As of March 19, 2021, GW&K was appointed as subadviser to the Fund and the Fund changed its name to "AMG GW&K ESG Bond Fund," adopted its current investment strategies, including beginning to use ESG factor analysis as part of the Fund's investment selection process, and began comparing its performance to the Bloomberg U.S. Aggregate Bond Index. The Fund's performance information for periods prior to March 19, 2021 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.

To obtain updated performance information please visit wealth.amg.com or call 800.548.4539.

Calendar Year Total Returns as of 12/31/24 (Class N)

 

Best Quarter: 7.40% (4th Quarter 2023)
Worst Quarter: -5.94% (2nd Quarter 2022)

 

Average Annual Total Returns as of 12/31/24
AMG GW&K ESG Bond Fund	1 Year	5 Years	10 Years
Class N Return Before Taxes	1.49%	-0.07%	1.79%
Class N Return After Taxes on Distributions	0.06%	-1.56%	0.24%
Class N Return After Taxes on Distributions and Sale of Fund Shares	0.88%	-0.43%	0.87%
Class I Return Before Taxes	1.75%	0.14%	1.96%
Bloomberg US Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	1.25%	-0.33%	1.35%

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 shares will vary.

Portfolio Management

Investment Manager

AMG Funds LLC

Subadviser

GW&K Investment Management, LLC

Portfolio Managers

Mary F. Kane, CFA
Partner and Portfolio Manager of GW&K;
Portfolio Manager of the Fund since March 2021.

Effective September 30, 2026, Ms. Kane will retire
from GW&K and no longer serve as a portfolio manager of the Fund.

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Brett Kozlowski, CFA
Principal and Portfolio Manager of GW&K;
Portfolio Manager of the Fund since July 2025.

Buying and Selling Fund Shares

Initial Investment Minimum

Class N
Regular Account: $2,000
Individual Retirement Account: $1,000

Class I
Regular Account: $100,000
Individual Retirement Account: $25,000

Additional Investment Minimum

Class N and Class I (all accounts): $100

TRANSACTION POLICIES

You may purchase or sell your shares of the Fund any day that the New York Stock Exchange is open for business, either through your registered investment professional or directly from or to the Fund. Shares may be purchased, sold or exchanged by mail at the address listed below, by phone at 800.548.4539, online at wealth.amg.com, or by bank wire (if bank wire instructions are on file for your account).

AMG Funds
c/o BNY Mellon Investment Servicing (US) Inc.
P.O. Box 534426
Pittsburgh, PA 15253-4426

Tax Information

The Fund intends to make distributions that are taxable to you as ordinary income or capital gains, except when your investment is through an IRA, 401(k), or other tax-advantaged investment plan. By investing in the Fund through such a plan, you will not be subject to tax on distributions from the Fund so long as the amounts distributed remain in the plan, but you will generally be taxed upon withdrawal of monies from the plan.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies, including the Investment Manager, AMG Distributors, Inc. (the "Distributor") and the Subadviser, may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.

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