UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSRS

CERTIFIED SHAREHOLDER REPORT OF REGISTERED

MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number: 811-4984

AMERICAN BEACON FUNDS

(Exact name of registrant as specified in charter)

220 East Las Colinas Boulevard, Suite 1200

Irving, Texas 75039

(Address of principal executive offices)-(Zip code)

GENE L. NEEDLES, JR., PRESIDENT

220 East Las Colinas Boulevard, Suite 1200

Irving, Texas 75039

(Name and address of agent for service)

Registrant’s telephone number, including area code: (817) 391-6100

Date of fiscal year end: December 31, 2021

Date of reporting period: June 30, 2021

Form N-CSRS is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSRS in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSRS, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSRS unless the Form displays a currently valid Office of Management and Budget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

About American Beacon Advisors

Since 1986, American Beacon Advisors, Inc. has offered a variety of products and investment advisory services to numerous institutional and retail clients, including a variety of mutual funds, corporate cash management, and separate account management.

Our clients include defined benefit plans, defined contribution plans, foundations, endowments, corporations, financial planners, and other institutional investors. With American Beacon Advisors, you can put the experience of a multi-billion dollar asset management firm to work for your company.

AHL MANAGED FUTURES STRATEGY FUND

Investing in derivative instruments involves liquidity, credit, interest rate and market risks. The use of quantitative models may lead to high levels of trading and concentration among certain investments, resulting in higher trading costs and return volatility. Investing in foreign and emerging market securities may involve heightened risk due to currency fluctuations and economic and political risks. Regulatory changes may impair the Fund’s ability to qualify for federal income tax treatment as a regulated investment company, which could result in the Fund and shareholders incurring significant income tax expense. The Fund may have high portfolio turnover risk, which could increase the Fund’s transaction costs and possibly have a negative impact on performance. Because the Fund may invest in fewer issuers than a more diversified portfolio, the fluctuating value of a single holding may have a greater effect on the value of the Fund.

AHL TARGETRISK FUND

Investing in derivative instruments involves liquidity, credit, interest rate and market risks. The use of quantitative models may lead to high levels of trading and concentration among certain investments, resulting in higher trading costs and return volatility. The Fund’s investments in high-yield or junk-rated securities are subject to greater levels of credit, interest rate, market and liquidity risks than investment-grade securities. In a period of sustained deflation, inflation index-linked securities may not pay any income and may suffer a loss. Investing in foreign and emerging market securities may involve heightened risk due to currency fluctuations and economic and political risks. Regulatory changes may impair the Fund’s ability to qualify for federal income tax treatment as a regulated investment company, which could result in the Fund and shareholders incurring significant income tax expense. The Fund may have high portfolio turnover risk, which could increase the Fund’s transaction costs and possibly have a negative impact on performance. Because the Fund may invest in fewer issuers than a more diversified portfolio, the fluctuating value of a single holding may have a greater effect on the value of the Fund.

AHL TARGETRISK CORE FUND

Investing in derivative instruments involves liquidity, credit, interest rate and market risks. The use of quantitative models may lead to high levels of trading and concentration among certain investments, resulting in higher trading costs and return volatility. Investing in foreign and emerging market securities may involve heightened risk due to currency fluctuations and economic and political risks. The Fund may have high portfolio turnover risk, which could increase the Fund’s transaction costs and possibly have a negative impact on performance. Because the Fund may invest in fewer issuers than a more diversified portfolio, the fluctuating value of a single holding may have a greater effect on the value of the Fund.

Any opinions herein, including forecasts, reflect our judgment as of the end of the reporting period and are subject to change. Each advisor’s strategies and the Fund’s portfolio composition will change depending on economic and market conditions. This report is not a complete analysis of market conditions and therefore, should not be relied upon as investment advice. Although economic and market information has been compiled from reliable sources, American Beacon Advisors, Inc. makes no representation as to the completeness or accuracy of the statements contained herein.

Contents

President’s Message

		Dear Shareholders,   Throughout this reporting period, the 24-hour news cycle has continued to closely follow the COVID-19 pandemic, ongoing global vaccination efforts and the rise of the delta variant, U.S. stimulus and infrastructure spending, and the reopening of our nation’s businesses and schools. After months of seclusion and uncertainty, we can finally see the proverbial light at the end of a tunnel – and a path forward to potentially brighter days – even as we learn to navigate a world facing additional virus variants.   However, during challenging times such as we’ve all experienced since March 2020, the fear of loss can be a powerful emotion. And it can cause many individuals to make short-term investment decisions that have the potential to sink their long-term financial objectives. We encourage you to remain

focused on achieving your long-term investment goals by working with financial professionals to develop a personal savings plan, conduct annual plan reviews, and make thoughtful, purposeful plan adjustments to help manage your evolving financial needs and goals. By investing in different investment styles and asset classes, you may be able to help mitigate financial risks across your portfolio. By allocating your portfolio according to your risk-tolerance level, you may be better positioned to withstand crises. By staying the course, you will be better positioned to achieve enduring financial success.

Since 1986, American Beacon has endeavored to provide investors with a disciplined approach to realizing long-term financial goals. As a manager of managers, we strive to provide investment products that may enable investors to participate during market upswings while potentially insulating against market downswings. The investment teams behind our mutual funds seek to produce consistent, long-term results rather than focus only on short-term movements in the markets. In managing our investment products, we emphasize identifying opportunities that offer the potential for long-term financial rewards.

Thank you for continuing your financial journey with American Beacon. For additional information about our investment products or to access your account information, please visit our website at www.americanbeaconfunds.com.

Best Regards,

Gene L. Needles, Jr.

President

American Beacon Funds

1

American Beacon AHL Managed Futures Strategy Fund^SM

Performance Overview

June 30, 2021 (Unaudited)

The Investor Class of the American Beacon AHL Managed Futures Strategy Fund (the “Fund”) returned 8.71% for the six months ended June 30, 2021.

For the period, the two sectors that drove performance were equities and commodities. All equity positions contributed positively over the period, but the top contributors were long positions in the S&P 500 and Euro-Stoxx indexes.

Commodities were the second-best performing sector as both the reopening trade and concerns about inflation helped long positions to move higher. Long positions in copper and WTI Crude added the most value.

Detracting from performance were the currency and fixed-income sectors. Currencies were the largest detractor. A long position in the euro versus the U.S. dollar as well as a short position in the South Korean won versus the U.S. dollar generated the largest losses.

Within fixed-income, shorter duration instruments detracted the most in light of the Federal Reserve June meeting which indicated an earlier rate hike than previously anticipated. Long positions in the eurodollar and short sterling incurred the largest losses. Partially offsetting some of the negative performance were positions in longer duration instruments including the U.S. Treasury ultra and long bonds.

Looking forward, the Fund’s sub-advisor will continue to implement its trading strategy designed to capitalize on price trends (up or down) in a broad range of global stock index, bond, currency, short-term interest rate and commodity futures markets seeking to achieve the Fund’s goal of capital growth.

2

American Beacon AHL Managed Futures Strategy Fund^SM

Performance Overview

June 30, 2021 (Unaudited)

3

American Beacon AHL TargetRisk Fund^SM

Performance Overview

June 30, 2021 (Unaudited)

The Investor Class of the American Beacon AHL TargetRisk Fund (the “Fund”) returned 6.06% for the six months ended June 30, 2021.

The first quarter was negative while the second quarter was profitable. The best sector for the period was equities, powered by a long position in the S&P 500 Index ending at an all-time high, as well as a long position in Canada’s S&P/TSX 60 Index. Inflation sensitive assets contributed the second most as investors heeded inflation signals from the market. Both the commodities index and inflation-linked bonds produced gains. Additionally, credit added value to performance in the risk-on environment. The high-yield indexes in North America and Europe performed the best. Lastly, fixed-income was the sole negative sector led by losses in French and United Kingdom 10-year bonds.

4

American Beacon AHL TargetRisk Fund^SM

Performance Overview

June 30, 2021 (Unaudited)

The correlation overlay was active for the bulk of the first quarter keeping exposures below normal levels. This overlay receded, however, in the second quarter which allowed for higher exposures. The correlation and volatility overlays remained inactive at the end of the period, while the momentum overlay on bonds continued to unwind its de-gear signal allowing the portfolio to gear back to full risk towards the end of the period.

Looking forward, the Fund’s sub-advisor will continue to implement its strategy of building a multi-asset portfolio and combining rigorous risk controls to provide a stable level of volatility while seeking to achieve the Fund’s goal of capital growth.

5

American Beacon AHL TargetRisk Core Fund^SM

Performance Overview

June 30, 2021 (Unaudited)

The Y Class of the American Beacon AHL TargetRisk Core Fund (the “Fund”) returned 2.79% for the six months ended June 30, 2021.

Equities led performance while bonds detracted. All but one equity market, the Istanbul 30 Index, gained during the period as investors generally bought into the recovery theme. The S&P 500 Index was the top contributor and ended the period at another all-time high. Canada’s S&P/TSX 60 Index added second most. Bonds produced a nearly opposite return profile during the period. Only the German Ultra Long Bund was able to make a meaningful gain while the rest of the sector was flat or negative. The United Kingdom and French 10-year bonds detracted the most.

From an overlay perspective, the Fund saw both the correlation and fixed income overlays engage during the first quarter which substantially reduced the overall exposure. As the calendar turned to the second quarter, the correlation overlay disengaged, and the fixed income momentum overlay gradually lifted leaving just a small residual of exposure being constrained by the momentum overlay by the end of period.

6

American Beacon AHL TargetRisk Core Fund^SM

Performance Overview

June 30, 2021 (Unaudited)

Looking forward, the Fund’s sub-advisor will continue to implement its strategy of building a multi-asset portfolio and combining rigorous risk controls to provide a stable level of volatility while seeking to achieve the Fund’s goal of capital growth.

7

American Beacon Funds^SM

Expense Examples

June 30, 2021 (Unaudited)

Fund Expense Example

As a shareholder of a Fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on purchase payments and redemption fees, if applicable, and (2) ongoing costs, including management fees, distribution (12b-1) fees, sub-transfer agent fees, and other Fund expenses. The Examples are intended to help you understand the ongoing cost (in dollars) of investing in the Funds and to compare these costs with the ongoing costs of investing in other mutual funds. The Examples are based on an investment of $1,000 invested at the beginning of the period in each Class and held for the entire period from January 1, 2021 through June 30, 2021.

Actual Expenses

The “Actual” lines of the tables provide information about actual account values and actual expenses. You may use the information on this page, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = $8.60), then multiply the result by the “Expenses Paid During Period” to estimate the expenses you paid on your account during this period. Shareholders of the Investor and R5 Classes that invest in the Fund through an IRA or Roth IRA may be subject to a custodial IRA fee of $15 that is typically deducted each December. If your account was subject to a custodial IRA fee during the period, your costs would have been $15 higher.

Hypothetical Example for Comparison Purposes

The “Hypothetical” lines of the tables provide information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratio and an assumed 5% per year rate of return before expenses (not the Fund’s actual return). You may compare the ongoing costs of investing in the Funds with other funds by contrasting this 5% hypothetical example and the 5% hypothetical examples that appear in the shareholder reports of the other funds. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. Shareholders of the Investor and R5 Classes that invest in the Funds through an IRA or Roth IRA may be subject to a custodial IRA fee of $15 that is typically deducted each December. If your account was subject to a custodial IRA fee during the period, your costs would have been $15 higher.

You should also be aware that the expenses shown in the table highlight only your ongoing costs and do not reflect any transaction costs charged by the Funds, such as sales charges (loads) or redemption fees, as applicable. Similarly, the expense examples for other funds do not reflect any transaction costs charged by those funds, such as sales charges (loads), redemption fees or exchange fees. Therefore, the “Hypothetical” lines of the tables are useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. If you were subject to any transaction costs during the period, your costs would have been higher.

8

American Beacon Funds^SM

Expense Examples

June 30, 2021 (Unaudited)

9

American Beacon Funds^SM

Expense Examples

June 30, 2021 (Unaudited)

10

American Beacon AHL Managed Futures Strategy Fund^SM

Consolidated Schedule of Investments

June 30, 2021 (Unaudited)

^A All or a portion represents positions held by the American Beacon Cayman Managed Futures Strategy Fund, Ltd.

See accompanying notes

11

American Beacon AHL Managed Futures Strategy Fund^SM

Consolidated Schedule of Investments

June 30, 2021 (Unaudited)

See accompanying notes

12

American Beacon AHL Managed Futures Strategy Fund^SM

Consolidated Schedule of Investments

June 30, 2021 (Unaudited)

See accompanying notes

13

American Beacon AHL Managed Futures Strategy Fund^SM

Consolidated Schedule of Investments

June 30, 2021 (Unaudited)

^A All or a portion represents positions held by the American Beacon Cayman Managed Futures Strategy Fund, Ltd.