Semi-Annual Report by Investment Company (Form N-CSRS)

REIT  Real Estate Investment Trust

1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

AMG Funds III (the "Trust") is an open-endmanagement investment company, organized as a Massachusetts business trust, and registered under the Investment Company Act of 1940, as amended (the "1940 Act"). Currently, the Trust consists of a number of different funds, each having distinct investment management objectives, strategies, risks, and policies. Included in this report is AMG GW&K International Small Cap Fund (the "Fund").

The Fund offers Class N, Class I and Class Z shares. Each class represents an interest in the same assets of the Fund. Although all share classes generally have identical voting rights, each share class votes separately when required by law. Different share classes may have different net asset values per share to the extent the share classes pay different distribution amounts and/or the expenses of such share classes differ. Each share class has its own expense structure. Please refer to a current prospectus for additional information on each share class.

The Fund's financial statements are prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP"), including accounting and reporting guidance pursuant to Accounting Standards Codification Topic 946 applicable to investment companies. U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates and such differences could be material. The following is a summary of significant accounting policies followed by the Fund in the preparation of its financial statements:

a. VALUATION OF INVESTMENTS

Equity securities traded on a national securities exchange or reported on the NASDAQ national market system ("NMS") are valued at the last quoted sales price on the primary exchange or, if applicable, the NASDAQ official closing price or the official closing price of the relevant exchange or, lacking any sales, at the last quoted bid price. Equity securities held by the Fund that are traded in the over-the-countermarket (other than NMS securities) are valued at the bid price. Foreign equity securities (securities principally traded in markets other than U.S. markets) held by the Fund are valued at the official closing price on the primary exchange or, for markets that either do not offer an official closing price or where the official closing price may not be representative of the overall market, the last quoted sale price.

Fixed income securities purchased with a remaining maturity of 60 days or less are valued at amortized cost, provided that the amortized cost value is approximately the same as the fair value of the security valued without the use of amortized cost. Investments in other open-endregistered investment companies are valued at their end of day net asset value per share.

The Fund's portfolio investments are generally valued based on independent market quotations or prices or, if none, "evaluative" or other market based valuations provided by third party pricing services. Pursuant to Rule 2a-5under the 1940 Act, the Fund's Board of Trustees (the "Board") designated AMG Funds LLC (the "Investment Manager") as the Fund's Valuation Designee to perform the Fund's fair value determinations. Such determinations are subject to Board oversight and certain reporting and other requirements intended to ensure that

the Board receives the information it needs to oversee the Investment Manager's fair value determinations.

Under certain circumstances, the value of certain Fund portfolio investments may be based on an evaluation of fair value, pursuant to procedures established by the Investment Manager and under the general supervision of the Board. The Fund may use the fair value of a portfolio investment to calculate its net asset value ("NAV") in the event that the market quotation, price or market based valuation for the portfolio investment is not readily available or otherwise not determinable pursuant to the Fund's valuation procedures, if the Investment Manager believes the quotation, price or market based valuation to be unreliable, or in certain other circumstances. When determining the fair value of an investment, the Investment Manager seeks to determine the price that the Fund might reasonably expect to receive from current sale of that portfolio investment in an arms-length transaction. Fair value determinations shall be based upon consideration of all available facts and information, including, but not limited to (i) attributes specific to the investment; (ii) fundamental and analytical data relating to the investment; and (iii) the value of other comparable securities or relevant financial instruments, including derivative securities, traded on other markets or among dealers.

The values assigned to fair value portfolio investments are based on available information and do not necessarily represent amounts that might ultimately be realized in the future, since such amounts depend on future developments inherent in long-term investments. Because of the inherent uncertainty of valuation, those estimated values may differ significantly from the values that would have been used had a ready market for the investments existed, and the differences could be material. The Board will be presented with quarterly reports, as of the most recent quarter end, summarizing all fair value activity, material fair value matters that occurred during the quarter, and all outstanding securities fair valued by the Fund. Additionally, the Board will be presented with an annual report that assesses the adequacy and effectiveness of the Investment Manager's process for determining the fair value of the Fund's investments.

With respect to foreign equity securities, securities held in the Fund that can be fair valued by the applicable fair value pricing service are fair valued on each business day provided that each individual price exceeds a pre-establishedconfidence level.

U.S. GAAP defines fair value as the price that a fund would receive to sell an asset or pay to transfer a liability in an orderly transaction between market participants at the measurement date. U.S. GAAP also establishes a framework for measuring fair value, and a three level hierarchy for fair value measurements based upon the transparency of inputs to the valuation of an asset or liability. Inputs may be observable or unobservable and refer broadly to the assumptions that market participants would use in pricing the asset or liability. Observable inputs reflect the assumptions market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Fund. Unobservable inputs reflect the Fund's own assumptions about the assumptions that market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. Each investment is assigned a level based upon the observability of the inputs which are significant to the overall valuation.

The three-tier hierarchy of inputs is summarized below:

Level 1 - inputs are quoted prices in active markets for identical investments (e.g., equity securities, open-endinvestment companies)

Level 2 - other observable inputs (including, but not limited to: quoted prices for similar assets or liabilities in markets that are active, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the assets or liabilities (such as interest rates, yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates) or other market corroborated inputs) (e.g., debt securities, government securities, foreign securities utilizing international fair value pricing, fair valued securities with observable inputs)

Level 3 - inputs are significant unobservable inputs (including the Fund's own assumptions used to determine the fair value of investments) (e.g., fair valued securities with unobservable inputs)

Changes in inputs or methodologies used for valuing investments may result in a transfer in or out of levels within the fair value hierarchy. The inputs or methodologies used for valuing investments may not necessarily be an indication of the risk associated with investing in those investments.

b. SECURITY TRANSACTIONS

Security transactions are accounted for as of trade date. Realized gains and losses on securities sold are determined on the basis of identified cost.

c. INVESTMENT INCOME AND EXPENSES

Dividend income is recorded on the ex-dividenddate. Dividends from foreign securities are recorded on the ex-dividenddate, and if after the fact, as soon as the Fund becomes aware of the ex-dividenddate. Interest income, which includes amortization of premium and accretion of discount on debt securities, is accrued as earned. Dividend and interest income on foreign securities is recorded gross of any withholding tax. Non-cashdividends included in dividend income, if any, are reported at the fair market value of the securities received. Other income and expenses are recorded on an accrual basis. Expenses that cannot be directly attributed to the Fund are apportioned among the funds in the Trust and other trusts or funds within the AMG Funds Family of Funds (collectively, the "AMG Funds Family") based upon their relative average net assets or number of shareholders. Investment income, realized and unrealized capital gains and losses, the common expenses of the Fund, and certain fund level expense reductions, if any, are allocated on a pro-ratabasis to each class based on the relative net assets of each class to the total net assets of the Fund.

d. DIVIDENDS AND DISTRIBUTIONS

Fund distributions resulting from either net investment income or realized net capital gains, if any, will normally be declared and paid at least annually in December. Distributions to shareholders are recorded on the ex-dividenddate. Distributions are determined in accordance with federal income tax law, which may differ from net investment income and net realized capital gains for financial

statement purposes (U.S. GAAP). Differences may be permanent or temporary. Permanent differences are reclassified among capital accounts in the financial statements to reflect their tax character. Permanent book and tax basis differences, if any, relating to shareholder distributions will result in reclassifications to paid-incapital. Temporary differences arise when certain items of income, expense and gain or loss are recognized in different periods for financial statement and tax purposes; these differences will reverse at some time in the future. There were no permanent differences during the year. Temporary differences are due to the mark-to-markettreatment of passive foreign investment companies and wash sales deferrals.

At November 30, 2025, the aggregate cost for federal income tax purposes approximates the aggregate cost for book purposes. The approximate cost of investments and the aggregate gross unrealized appreciation and depreciation for federal income tax purposes were as follows:

e. FEDERAL TAXES

The Fund currently qualifies as an investment company and intends to comply with the requirements under Subchapter M of the Internal Revenue Code of 1986, as amended (the "Code"), and to distribute substantially all of its taxable income and gains to its shareholders and to meet certain diversification and income requirements with respect to investment companies. The Investment Manager has analyzed the Fund's tax positions taken on federal income tax returns for all open tax years (generally, the three prior taxable years), and has concluded that no provision for federal income tax is required in the Fund's financial statements. Additionally, the Investment Manager is not aware of any tax position for which it is reasonably possible that the total amounts of unrecognized tax benefit/detriment will change materially in the next twelve months.

Furthermore, based on the Fund's understanding of the tax rules and rates related to income, gains and transactions for the foreign jurisdictions in which it invests, the Fund will provide for foreign taxes, and where appropriate, deferred foreign taxes.

f. CAPITAL LOSS CARRYOVERS AND DEFERRALS

As of May 31, 2025, the Fund had capital loss carryovers for federal income tax purposes as shown in the following chart. These amounts may be used to offset future realized capital gains indefinitely, and retain their character as short-term and/or long-term.

h. REPURCHASE AGREEMENTS AND JOINT REPURCHASE AGREEMENTS

The Fund may enter into third-party and bilateral repurchase agreements for temporary cash management purposes and for reinvestment of cash collateral on securities lending transactions under the securities lending program offered by The Bank of New York Mellon ("BNYM") (the "Securities Lending Program") (collectively, "Repurchase Agreements"). The value of the underlying collateral, including accrued interest, must equal or exceed the value of the Repurchase Agreements during the term of the agreement. For joint repurchase agreements, the Fund participates on a pro rata basis with other clients of BNYM in its share of the underlying collateral under such joint repurchase agreements and in its share of proceeds from any repurchase or other disposition of the underlying collateral. The underlying collateral for all Repurchase Agreements is held by the Fund's custodian or at the Federal Reserve Bank. If the seller defaults and the value of the collateral declines, or if bankruptcy proceedings commence with respect to the seller of the security, realization of the collateral by the Fund may be delayed or limited. Pursuant to the Securities Lending Program, the Fund is indemnified for such losses by BNYM on joint repurchase agreements.

At November 30, 2025, the market value of Repurchase Agreements outstanding was $2,951,859.

i. FOREIGN CURRENCY TRANSLATION

The books and records of the Fund are maintained in U.S. Dollars. The value of investments, assets and liabilities denominated in currencies other than U.S. Dollars are translated into U.S. Dollars based upon current foreign exchange rates. Purchases and sales of foreign investments, income and expenses are converted into U.S. Dollars based on currency exchange rates prevailing on the respective dates of such transactions. Net realized and unrealized gain (loss) on foreign currency transactions represent: (1) foreign exchange gains and losses from the sale and holdings of foreign currencies; (2) gains and losses between trade date and settlement date on investment securities transactions and foreign currency exchange contracts; and (3) gains and losses from the difference between amounts of interest and dividends recorded and the amounts actually received.

The Fund does not isolate the net realized and unrealized gain or loss resulting from changes in exchange rates from the fluctuations in market prices of securities held. Such fluctuations are included with the net realized and unrealized gain or loss on investments.

2. AGREEMENTS AND TRANSACTIONS WITH AFFILIATES

The Trust has entered into an investment advisory agreement under which the Investment Manager, a subsidiary and the U.S. wealth platform of Affiliated Managers Group, Inc. ("AMG"), serves as investment manager to the Fund and is

responsible for the Fund's overall administration and operations. The Investment Manager selects and recommends, subject to the approval of the Board and, in certain circumstances, shareholders, the subadviser for the Fund and monitors the subadviser's investment performance, security holdings and investment strategies. The Fund's investment portfolio is managed by GW&K Investment Management, LLC ("GW&K"), who serves pursuant to a subadvisory agreement with the Investment Manager. AMG indirectly owns a majority interest in GW&K.

Investment management fees are paid directly by the Fund to the Investment Manager based on average daily net assets. For the six months ended November 30, 2025, the Fund paid an investment management fee at the annual rate of 0.69% of the average daily net assets of the Fund. The fee paid to GW&K for its services as subadviser is paid out of the fee the Investment Manager receives from the Fund and does not increase the expenses of the Fund.

The Investment Manager has contractually agreed, through at least October 1, 2026, to waive management fees and/or pay or reimburse fund 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) to 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 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 Board, 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.

For the six months ended November 30, 2025, the Investment Manager reimbursed the Fund $79,688, and did not recoup any previously reimbursed expenses. At November 30, 2025, the Fund's expiration of reimbursements subject to recoupment was as follows: