AMG FUNDS IV

	Summary Prospectus	May 24, 2021 (as revised August 27, 2021)
	AMG GW&K Small/Mid Cap Growth Fund
	(formerly AMG GW&K Small Cap Fund II, which was formerly AMG Managers LMCG Small Cap Growth Fund)

Class N: ACWDX

Class I: ACWIX

Class Z: ACWZX

Before you invest, you may want to review the Fund’s prospectus and statement of additional information, which contain more information about the Fund and its risks. You can find the Fund’s prospectus, statement of additional information, reports to shareholders and other information about the Fund online at
https://www.amgfunds.com/resources/order_literature.html. You can also get this information at no cost by calling 1-800-548-4539 or by sending an e-mail request to shareholderservices@amg.com. The current prospectus and statement of additional information, dated May 24, 2021, as revised or supplemented from time to time, are incorporated by reference into this summary prospectus.

Investment Objective

The Fund seeks to provide long-term 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	Class Z¹
Management Fee²	0.62%	0.62%	0.62%
Distribution and Service (12b-1) Fees	0.19%	None	None
Other Expenses²	0.44%	0.49%	0.44%
Total Annual Fund Operating Expenses	1.25%	1.11%	1.06%
Fee Waiver and Expense Reimbursements³	(0.24)%	(0.24)%	(0.24)%
Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements³	1.01%	0.87%	0.82%

¹	Because Class Z shares commenced operations on or following the date of this Prospectus, these amounts are based on estimates for the current fiscal year.

²	Expense information has been restated to reflect current fees.

AMG Funds LLC (the “Investment Manager”) has contractually agreed, through at least March 1, 2023, 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 0.82% 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 IV 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 Example includes the Fund’s contractual expense limitation through March 1, 2023. 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	$103	$360	$651	$1,479
Class I	$ 89	$317	$576	$1,319
Class Z	$ 84	$301	$549	$1,261

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 126% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in securities of small- and mid-capitalization companies. The Fund primarily invests in common stock and preferred stock of U.S. small- and mid-capitalization companies. The Fund currently defines small- and mid-capitalization companies to be those with market capitalizations at the time of purchase between $250 million and $10 billion or otherwise within the range of capitalizations of companies in the Russell 2500 Growth Index (between $65.69 million and $19.442 billion as of May 7, 2021, the date of the latest reconstitution of the Index (implemented by the Index June 25, 2021)). The Fund may continue to hold securities of a portfolio company that subsequently drops below or appreciates above this threshold.

SUM086-0821

AMG GW&K Small/Mid Cap Growth Fund SUMMARY PROSPECTUS

Because of this, the Fund may have less than 80% of its net assets in securities of small- and mid-capitalization companies at any given time.

Through its fundamental research and proprietary screening, GW&K Investment Management, LLC, the subadviser to the Fund (“GW&K” or the “Subadviser”), seeks to identify quality companies with growth oriented characteristics. GW&K seeks to assemble a portfolio of securities diversified as to companies and sectors.

The Subadviser seeks to focus on quality small- and mid-capitalization companies with sound management and long-term sustainable growth. In selecting companies for the Fund, the Subadviser looks for firms with the following key attributes:

○	Experienced, tenured, high quality management;
○	Business models that deliver consistent long-term growth;
○	Leading companies in attractive and defensible niche markets;
○	Strong financial characteristics; and
○	Appropriate valuation.

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.

Market Risk—market prices of investments held by the Fund may fall rapidly or unpredictably due to a variety of factors, including economic, political, 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 such as the COVID-19 outbreak, or in response to events that affect particular industries or companies.

Small- and Mid-Capitalization Stock Risk—the stocks of small- and mid-capitalization companies often have greater price volatility, lower trading volume, and less liquidity than the stocks of larger, more established companies.

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.

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.

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 information technology and healthcare sectors may comprise a significant portion of the Fund's portfolio. The information technology sector may be affected by technological obsolescence, short product cycles, falling prices and profits, competitive pressures and general market conditions. Stocks in the health care sector may be affected by technological obsolescence, changes in regulatory approval policies for drugs, medical devices or procedures and changes in governmental and private payment systems.

High Portfolio Turnover Risk—higher portfolio turnover may adversely affect Fund performance by increasing Fund transaction costs and may increase a shareholder’s tax liability.

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.

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

As of March 19, 2021, GW&K was appointed as subadviser to the Fund and the Fund changed its name to “AMG GW&K Small Cap Fund II” and made changes to its principal investment strategies. As of May 21, 2021, the Fund changed its name to “AMG GW&K Small/Mid Cap Growth Fund,” adopted its current investment strategies and began comparing its performance to the Russell 2500 Growth Index. The Fund’s performance information for periods prior to May 21, 2021 reflects the Fund’s investment strategy that was in effect at that time and may have been different had the Fund’s current investment strategy been in effect.

Because the Fund’s Class Z shares have not operated for a full calendar year, performance history for this share class is not available. Class Z shares would have similar annual returns as Class N and Class I shares because all of the classes are invested in the same portfolio of securities. However, Class Z shares are subject to different expenses than Class N and Class I shares, and Class Z share performance would vary to that extent.

To obtain updated performance information, please visit www.amgfunds.com or call 800.548.4539.

AMG Funds

AMG GW&K Small/Mid Cap Growth Fund SUMMARY PROSPECTUS

Calendar Year Total Returns as of 12/31/20 (Class N)

Best Quarter: 31.00% (2nd Quarter 2020)
Worst Quarter: -27.36% (3rd Quarter 2011)

Average Annual Total Returns as of 12/31/20
AMG GW&K Small/Mid Cap Growth Fund	1 Year	5 Years	10 Years	Since Inception¹
Class N Return Before Taxes
Class N Return Before Taxes	45.61%	13.27%	11.93%	—
Class N Return After Taxes on Distributions	44.25%	13.05%	10.85%	—
Class N Return After Taxes on Distributions and Sale of Fund Shares	27.94%	10.64%	9.34%	—
Class I Return Before Taxes	45.89%	13.51%	—	11.38%
Russell 2500™ Growth Index² (reflects no deduction for fees, expenses, or taxes)
	40.47%	18.68%	15.00%	14.64%
Russell 2000^®Growth Index² (reflects no deduction for fees, expenses, or taxes)
	34.63%	16.36%	13.48%	12.86%

¹	Class I and Index performance shown reflects performance since the inception date of the Fund’s Class I shares on June 1, 2011.
²	The Russell 2500™ Growth Index replaced the Russell 2000^®Growth Index as the Fund’s benchmark on May 21, 2021 because the Investment Manager and Subadviser believe the new benchmark is more representative of the Fund’s current investment strategies.

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 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.

Portfolio Management

Investment Manager

AMG Funds LLC

Subadviser

GW&K Investment Management, LLC

Portfolio Managers
Daniel L. Miller, CFA
Partner and Director of Equities of GW&K;
Portfolio Manager of the Fund since March 2021.

Joseph C. Craigen, CFA
Partner and Equity Portfolio Manager of GW&K;
Portfolio Manager of the Fund since March 2021.

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

Class Z^*

Regular Account: $5,000,000
Individual Retirement Account: $50,000

Additional Investment Minimum

Class N and Class I (all accounts): $100
Class Z (all accounts): $1,000

^*Individual retirement accounts may only invest in Class Z shares by purchasing shares directly from the Fund.

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 with the Fund. Shares may be purchased, sold or exchanged by mail at the address listed below, by phone at 800.548.4539, online at www.amgfunds.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 9769
Providence, RI 02940-9769

Tax Information

The Fund intends to make distributions that are taxable to you as ordinary income, qualified dividend income or capital gains, except when your investment is in 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.

AMG Funds

AMG GW&K Small/Mid Cap Growth Fund SUMMARY PROSPECTUS

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.

AMG Funds