TRIO Trio Merger Corp. (MM)

		American Beacon Stephens Mid-Cap Growth Fund SM		Ticker Symbol: A: SMFAX   C: SMFCX   Y: SMFYX   Institutional: SFMIX   Investor: STMGX

SUMMARY PROSPECTUS		MARCH 28, 2013  (supplemented May 31, 2013)

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. The current prospectus and statement of additional information dated March 28, 2013 and most recently supplemented May 31, 2013, are incorporated by reference into this summary prospectus. You can find the Fund’s prospectus, statement of additional information and other information about the Fund online at www.americanbeaconfunds.com/resource_center/MutualFundForms.aspx. You can also get this information at no cost by calling 800-658-5811 or by sending an email request to americanbeaconfunds@ambeacon.com.

Investment Objective

The Fund seeks long-term growth of capital.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales discounts if you and your eligible family members invest, or agree to invest in the future, at least $50,000 in the A Class shares of the American Beacon Funds. More information about these and other discounts is available from your financial professional and in “Choosing Your Share Class” on page 31 of the Prospectus and “Additional Purchase and Sale Information for A Class Shares” on page 35 of the statement of additional information.

Shareholder fees
(fees paid directly from your investment)

Share classes

A

C

Y

Institutional

Investor

Maximum sales charge imposed on purchases (as a percentage of offering price)

5.75%

None

None

None

None

Maximum deferred sales charge load (as a percentage of the lower of original offering price or redemption proceeds)

None

1.00%

None

None

None

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

		Share classes
		A				C				Y				Institutional				Investor
Management fees			0.59%				0.59%				0.59%				0.59%				0.59%
Distribution and/or service (12b-1) fees			0.25%				1.00%				0.00%				0.00%				0.00%
Other expenses 1			0.99%				12.95%				3.26%				0.69%				1.08%
Acquired Fund Fees and Expenses			0.01%				0.01%				0.01%				0.01%				0.01%
Total annual fund operating expenses			1.84%				14.55%				3.86%				1.29%				1.68%
Expense reduction and reimbursement			0.34%				12.30%				2.76%				0.29%				0.30%
Total annual fund operating expenses after expense reduction and reimbursement 2			1.50%				2.25%				1.10%				1.00%				1.38%

1

The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets provided in the Fund’s Financial Highlights table, which reflects the operating expenses of the Fund and does not include Acquired Fund Fees and Expenses.

2

The Manager has contractually agreed to reduce and/or reimburse the A Class, C Class, Y Class, Institutional Class, and Investor Class of the Fund for Other Expenses through April 30, 2014 to the extent that Total Annual Fund Operating Expenses for the Fund exceed 1.49%, 2.24%, 1.99%, 0.09% and 1.37% for the A Class, C Class, Y Class, Institutional Class, and Investor Class, respectively (excluding taxes, brokerage commissions, acquired fund fees and expenses and other extraordinary expenses such as litigation). The contractual expense arrangement can be changed by approval of a majority of the Fund’s Board of Trustees. The Manager can be reimbursed by the Fund for any contractual or voluntary fee reductions or expense reimbursements if reimbursement to the Manager (a) occurs within three years after the Manager’s own reduction or reimbursement and (b) does not cause the Total Annual Fund Operating Expenses of a class to exceed the percentage limit contractually agreed.

Example.

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Share classes		1 year				3 years				5 years				10 years
A		$	719			$	1,089			$	1,483			$	2,583
C		$	328			$	2,940			$	5,158			$	9,096
Y		$	112			$	923			$	1,753			$	3,913
Institutional		$	102			$	381			$	680			$	1,531
Investor		$	141			$	501			$	885			$	1,962

Assuming no redemption of shares:

Share class		1 year				3 years				5 years				10 years
C		$	228			$	2,940			$	5,158			$	9,096

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 27% of the average value of its portfolio.

of the largest company in the Russell Midcap® Index, which was $25.0 billion as of December 31, 2012.

Most of the assets of the Fund are invested in U.S. common stocks Stephens Investment Management Group, LLC (“SIMG”) believes have clear indicators of future earnings growth, or that demonstrate other potential for growth of capital. The Fund may invest in other securities, including preferred stock, securities convertible into common stock, U.S dollar denominated foreign stock traded on U.S. exchanges, American Depositary Receipts (“ADRs”) and real estate investment trusts (“REITs”). In selecting companies for the Fund, SIMG employs quantitative analysis and fundamental research with a focus on earnings growth. SIMG will sell a security when appropriate and consistent with the Fund’s investment objectives and policies.

The Fund may also invest cash balances in other investment companies, including money market funds.

compares to the Russell Midcap® Growth Index, which is the Fund’s primary benchmark and is a broad measure of market performance. In addition, the Fund’s performance is compared to the S&P 500® Index, which is the Fund’s secondary index and is provided to offer a broader market perspective.

The Investor Class and Institutional Class shares of the Fund have adopted the performance history and financial statements of the Class A and Class I shares, respectively, of the Fund’s predecessor. The performance of the Fund’s Investor Class shares shown in the chart and table below represents the returns achieved by the Class A shares of the Fund’s predecessor from February 1, 2006 to February 24, 2012, and the performance of the Investor Class from February 24, 2012 through December 31, 2012. The table below also shows the performance of the A Class, C Class, Y Class and Institutional Class shares of the Fund. The performance shown for the Institutional Class shares of the Fund represents: (1) the returns achieved by the Class A Shares of the Fund’s predecessor from February 1, 2006 to August 31, 2006, the inception date of the predecessor Fund’s Class I shares; (2) the performance of the Class I shares from inception to February 24, 2012; and (3) the performance of the Institutional Class shares from February 24, 2012 through December 31, 2012. Returns shown for the Fund’s Y Class, A Class and C Class shares represent the returns achieved by the Class A shares of the Fund’s predecessor from February 1, 2006 to February 24, 2012, and the performance of the Y Class, A Class and C Class shares, respectively, from February 24, 2012 through December 31, 2012. In each case, the newer share classes would have had similar annual returns to the predecessor Fund’s Class A and Class I shares because the shares of each class represent investments in the same portfolio securities. However, because the Class A shares of the predecessor Fund had higher expenses than the Fund’s Institutional Class and Y Class shares now have, the total returns were lower than the Institutional Class and Y Class shares would have realized had the Y Class shares been in existence since February 1, 2006. Since the Investor Class shares had lower expenses than the Fund’s A Class and C Class shares now have, its performance was better than the performance of the A Class and C Class shares would have realized in the same period. The performance of the Fund and the Fund’s predecessor shown in the bar chart below do not include sales charges. If sales charges were reflected, returns would be lower. You may obtain updated performance information on the Fund’s website at www.americanbeaconfunds.com. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Calendar year total returns for Investor Class shares

Highest Quarterly Return: (2/1/06 through 12/31/12)		16.31% (3rd Quarter 2009)
Lowest Quarterly Return: (2/1/06 through 12/31/12)		-28.39% (4th Quarter 2008)

  

		Average Annual Total Returns 1
		For the periods ended December 31, 2012
		Inception Date of Class
Investor Class		2/1/2006				1 Year				5 Years				Since Inception
Return Before Taxes							14.75%				2.71%				4.89%
Return After Taxes on Distributions							14.65%				2.69%				4.88%
Return After Taxes on Distributions and Sale of Fund Shares							9.72%				2.32%				4.24%

Share Class (before taxes)		Inception Date of Class				1 Year				5 Years				Since Inception
A			2/24/2012				8.15%				1.50%				3.99%
C			2/24/2012				13.26%				2.62%				4.82%
Y			2/24/2012				15.26%				2.80%				4.96%
Institutional			8/31/2006				15.19%				2.99%				7.12%

Indices (reflects no deduction for fees, expenses or taxes)		1 Year				5 Years				Since Inception (2/1/2006)
Russell Mid-Cap® Growth Index			15.81	%			3.23	%			4.59	%
Lipper Mid-Cap Growth Funds Index			13.37	%			1.49	%			4.53	%
S&P 500 Index			16.00	%			1.66	%			3.78	%

Management

The Manager

The Fund has retained American Beacon Advisors, Inc. to serve as its Manager.

Sub-Advisor

The Fund’s investment sub-advisor is Stephens Investment Management Group, LLC

Portfolio Managers

Stephens Investment Management Group, LLC
Ryan Crane Senior Portfolio Manager		Since Fund Inception (2006)*
John Thornton Co-Portfolio Manager		Since Fund Inception (2006)*
Kelly Ranucci Co-Portfolio Manager		Since 2011**
Sam Chase Co-Portfolio Manager		Since 2011**

*

Predecessor Fund inception date

* *

Including Predecessor Fund

Purchase and Sale of Fund Shares

You may purchase, redeem or exchange shares of the Fund on any business day, which is any day the New York Stock Exchange is open for business. You may purchase, redeem or

American Beacon Stephens Mid-Cap Growth Fund

3

Summary Prospectus | March 28, 2013

exchange Institutional Class, Investor Class and Y Class shares directly from the Fund by calling 1-800-658-5811, writing to the Fund at P.O. Box 219643, Kansas City, MO 64121-9643, or visiting www.americanbeaconfunds.com . For overnight delivery, please mail your request to American Beacon Funds, c/o BFDS, 330 West 9 ^th Street, Kansas City, MO 64105. You also may purchase, redeem or exchange all classes of shares offered in this prospectus through a broker-dealer or other financial intermediary. The minimum initial purchase into the Fund is $250,000 for Institutional Class shares, $100,000 for Y Class shares, $2,500 for A Class and Investor Class shares, and $1,000 for C Class shares. The minimum subsequent investment by wire is $500 for A Class, C Class and Investor Class shares. No minimums apply to subsequent investments by wire for other classes of shares. For all classes, the minimum subsequent investment is $50 if the investment is made by ACH, check or exchange.

Tax Information

Dividends and capital gain distributions, if any, which you receive from the Fund are subject to federal income tax and may also be subject to state and local taxes, unless your account is tax-exempt or tax deferred (in which case you may be taxed later, upon the withdrawal of your investment from such account).

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and the Fund’s distributor or the Manager 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 individual financial adviser to recommend the Fund over another investment. Ask your individual financial adviser or visit your financial intermediary’s website for more information.