497K

Summary Prospectus

May 1, 2025

SunAmerica Series Trust

SA MFS Total Return Portfolio

(Class 1, Class 2 and Class 3 Shares)

SunAmerica Series Trust’s Statutory Prospectus and Statement of Additional Information, each dated May 1, 2025, as amended and supplemented from time to time, and the most recent shareholder reports are incorporated into and made part of this Summary Prospectus by reference. The Portfolio is offered only to the separate accounts of certain affiliated and unaffiliated life insurance companies and to other mutual funds. This Summary Prospectus is not intended for use by other investors.

Before you invest, you may want to review SunAmerica Series Trust’s Statutory Prospectus, which contains more information about the Portfolio and its risks. You can find the Statutory Prospectus and the above-incorporated information online at https://www.corebridgefinancial.com/getprospectus. You can also get this information at no cost by calling (800) 445-7862 or by sending an e-mail request to fundprospectus@corebridgefinancial.com.

The Securities and Exchange Commission has not approved or disapproved these securities, nor has it determined that this Summary Prospectus is accurate or complete. It is a criminal offense to state otherwise.

Investment Goal

The Portfolio’s investment goals are reasonable current income, long term capital growth and conservation of capital.

Fees and Expenses of the Portfolio

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Portfolio. The table and the example below do not reflect the separate account fees charged in the variable annuity or variable life insurance policy (“Variable Contracts”) in which the Portfolio is offered. If separate account fees were shown, the Portfolio’s annual operating expenses would be higher. Please see your Variable Contract prospectus for more details on the separate account fees.

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

	Class 1	Class 2	Class 3
Management Fees	0.65%	0.65%	0.65%
Service (12b-1) Fees	None	0.15%	0.25%
Other Expenses	0.06%	0.06%	0.06%
Total Annual Portfolio Operating Expenses	0.71%	0.86%	0.96%

Expense Example

This Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and then redeem or hold 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 Portfolio’s

operating expenses remain the same (except that the Example incorporates any applicable fee waiver and/or expense limitation arrangements for only the first year). The Example does not reflect charges imposed by the Variable Contract. If the Variable Contract fees were reflected, the expenses would be higher. See the Variable Contract prospectus for information on such charges. Although your actual costs may be higher or lower, based on these assumptions and the net expenses shown in the fee table, your costs would be:

	1 Year	3 Years	5 Years	10 Years
Class 1	$73	$227	$395	$883
Class 2	88	274	477	1,061
Class 3	98	306	531	1,178

Portfolio Turnover

The Portfolio 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. These costs, which are not reflected in annual portfolio operating expenses or in the Example, affect the Portfolio’s performance.

During the most recent fiscal year, the Portfolio’s portfolio turnover rate was 30% of the average value of its portfolio.

Principal Investment Strategies of the Portfolio

The Portfolio attempts to achieve its investment goal by investing in a combination of equity and fixed income securities. Under normal market conditions, the Portfolio will generally invest approximately 60% of its assets in equity securities and approximately 40% of its assets in debt instruments. These weightings do not reflect the Portfolio’s cash balance and can vary over time due to

SunAmerica Series Trust

- 1 -

SA MFS Total Return Portfolio

market movement and cash flows. The Portfolio’s investments in fixed income securities may include, but are not limited to, corporate bonds, U.S. Government securities, mortgage- and asset-backed securities and foreign government securities. The Portfolio may also purchase and sell debt instruments on a when-issued, delayed delivery, or forward commitment basis where payment and delivery take place at a future settlement date, including mortgage-backed securities purchased or sold in the to be announced (TBA) market. Generally, substantially all of the Portfolio’s investments in debt instruments are investment grade quality debt instruments.

The Portfolio may invest in foreign securities (up to 25% of net assets).

Of the Portfolio’s investments in equity securities, the subadviser focuses on investing in the stocks of companies that it believes are undervalued compared to their perceived worth (value companies). Value companies tend to have stock prices that are low relative to their earnings, dividends, assets, or other financial measures. The subadviser normally invests a portion of the Portfolio’s assets in income-producing equity securities. While the Portfolio may invest the equity portion of its assets in companies of any size, the Portfolio primarily invests in companies with large capitalizations.

The subadviser uses an active bottom-up investment approach to buying and selling investments for the Portfolio. Investments are selected primarily based on fundamental analysis of individual issuers and/or instruments in light of the issuer’s financial condition and market, economic, political, and regulatory conditions. Factors considered for equity securities may include analysis of an issuer’s earnings, cash flows, competitive position, and management ability. Factors considered for debt instruments may include the instrument’s credit quality, collateral characteristics, and indenture provisions, and the issuer’s management ability, capital structure, leverage, and ability to meet its current obligations. The subadviser may also consider environmental, social, and governance (ESG) factors in its fundamental investment analysis where MFS believes such factors could materially impact the economic value of an issuer. ESG factors considered may include, but are not limited to, climate change, resource depletion, an issuer’s governance structure and practices, data protection and privacy issues, and diversity and labor practices. Quantitative screening tools that systematically evaluate the valuation, price and earnings momentum, earnings quality, and other factors of the issuer of an equity security or the structure of a debt instrument may also be considered.

Principal Risks of Investing in the Portfolio

As with any mutual fund, there can be no assurance that the Portfolio’s investment goal will be met or that the net return on an investment in the Portfolio will exceed what could have been obtained through other investment or savings vehicles. Shares of the Portfolio are not bank deposits and are not guaranteed or insured by any bank, government entity or the Federal Deposit Insurance Corporation. If the value of the assets of the Portfolio goes down, you could lose money.

The following is a summary of the principal risks of investing in the Portfolio.

Equity Securities Risk. The Portfolio invests principally in equity securities and is therefore subject to the risk that stock prices will fall and may underperform other asset classes. Individual stock prices fluctuate from day-to-day and may decline significantly.

When-Issued and Delayed Delivery Transactions Risk. When-issued and delayed delivery securities involve the risk that the security the Portfolio buys will lose value prior to its delivery. There also is the risk that the security will not be issued or that the other party to the transaction will not meet its obligation. If this occurs, the Portfolio may lose both the investment opportunity for the assets it set aside to pay for the security and any gain in the security’s price.

Leverage Risk. The Portfolio may engage in certain transactions that may expose it to leverage risk, such as reverse repurchase agreements, loans of portfolio securities, and the use of when-issued, delayed delivery or forward commitment transactions and derivatives. The use of leverage may cause the Portfolio to liquidate portfolio positions at inopportune times in order to meet regulatory asset coverage requirements, fulfill leverage contract terms, or for other reasons. Leveraging, including borrowing, tends to increase the Portfolio’s exposure to market risk, interest rate risk or other risks, and thus may cause the Portfolio to be more volatile than if the Portfolio had not utilized leverage.

Counterparty Risk. Counterparty risk is the risk that a counterparty to a security, loan or derivative held by the Portfolio becomes bankrupt or otherwise fails to perform its obligations due to financial difficulties. The Portfolio may experience significant delays in obtaining any recovery in a bankruptcy or other reorganization proceeding, and there may be no recovery or limited recovery in such circumstances.

Convertible Securities Risk. The values of the convertible securities in which the Portfolio may invest will

SunAmerica Series Trust

- 2 -

SA MFS Total Return Portfolio

be affected by market interest rates, the risk that the issuer may default on interest or principal payments and the value of the underlying common stock into which these securities may be converted. Specifically, certain types of convertible securities may pay fixed interest and dividends; their values may fall if market interest rates rise and rise if market interest rates fall. Additionally, an issuer may have the right to buy back or “call” certain of the convertible securities at a time unfavorable to the Portfolio.

Preferred Stock Risk. Preferred stockholders’ liquidation rights are subordinate to the company’s debt holders and creditors. If interest rates rise, the fixed dividend on preferred stocks may be less attractive and the price of preferred stocks may decline. Deferred dividend payments by an issuer of preferred stock could have adverse tax consequences for the Portfolio and may cause the preferred stock to lose substantial value.

Depositary Receipts Risk.Depositary receipts are generally subject to the same risks as the foreign securities that they evidence or into which they may be converted. The issuers of unsponsored depositary receipts are not obligated to disclose information that is considered material in the United States. Therefore, there may be less information available regarding the issuers and there may not be a correlation between such information and the market value of the depositary receipts. Certain depositary receipts are not listed on an exchange and therefore are subject to illiquidity risk.

Value Investing Risk. The subadviser’s judgment that a particular security is undervalued in relation to the company’s fundamental economic value may prove incorrect.

Large-Cap Companies Risk. Large-cap companies tend to be less volatile than companies with smaller market capitalizations. In exchange for this potentially lower risk, the Portfolio’s value may not rise as much as the value of portfolios that emphasize smaller companies. Larger, more established companies may be unable to respond quickly to new competitive challenges, such as changes in technology and consumer tastes. Larger companies also may not be able to attain the high growth rate of successful smaller companies, particularly during extended periods of economic expansion.

Foreign Investment Risk. The Portfolio’s investments in the securities of foreign issuers or issuers with significant exposure to foreign markets involve additional risk. Foreign countries in which the Portfolio invests may have markets that are less liquid, less regulated and more

volatile than U.S. markets. The value of the Portfolio’s investments may decline because of factors affecting the particular issuer as well as foreign markets and issuers generally, such as unfavorable government actions, and political or financial instability and other conditions or events (including, for example, military confrontations, war, terrorism, sanctions, disease/virus, outbreaks and epidemics). Lack of relevant data and reliable public information may also affect the value of these securities.

Foreign Sovereign Debt Risk. Foreign sovereign debt securities are subject to the risk that a governmental entity may delay or refuse to pay interest or to repay principal on its sovereign debt. If a governmental entity defaults, it may ask for more time in which to pay or for further loans.

ESG Investment Risk. The Portfolio’s adherence to its ESG criteria and application of related analyses when selecting investments may impact the Portfolio’s performance, including relative to similar funds that do not adhere to such criteria or apply such analyses. Additionally, the Portfolio’s adherence to its ESG criteria and application of related analyses in connection with identifying and selecting investments may require subjective analysis and may be more difficult if data about a particular company or market is limited, such as with respect to issuers in emerging markets countries. The Portfolio may invest in companies that do not reflect the beliefs and values of any particular investor. Socially responsible norms differ by country and region, and a company’s ESG practices or the subadviser’s assessment of such may change over time. ESG characteristics may not be the only factors considered in selecting investments and as a result, the Portfolio’s investments may not have favorable ESG characteristics or high ESG ratings.

Bonds Risk. The value of your investment in the Portfolio may go up or down in response to changes in interest rates or defaults (or even the potential for future defaults) by bond issuers.

Credit Risk. Credit risk applies to most debt securities, but is generally not a factor for obligations backed by the “full faith and credit” of the U.S. Government. The Portfolio could lose money if the issuer of a debt security is unable or perceived to be unable to pay interest or to repay principal when it becomes due.

An issuer with a lower credit rating will be more likely than a higher rated issuer to default or otherwise become unable to honor its financial obligations. Issuers with low credit ratings typically issue junk bonds. In addition to the risk of default, junk bonds may be more volatile, less

SunAmerica Series Trust

- 3 -

SA MFS Total Return Portfolio

liquid, more difficult to value and more susceptible to adverse economic conditions or investor perceptions than other bonds.

Call Risk. The risk that an issuer will exercise its right to pay principal on a debt obligation (such as a mortgage-backed security or convertible security) that is held by the Portfolio earlier than expected. This may happen when there is a decline in interest rates. Under these circumstances, the Portfolio may be unable to recoup all of its initial investment and will also suffer from having to reinvest in lower-yielding securities.

Extension Risk. The risk that an issuer will exercise its right to pay principal on an obligation held by the Portfolio (such as a mortgage-backed security) later than expected. This may happen when there is a rise in interest rates. Under these circumstances the value of the obligation will decrease, and the Portfolio will also suffer from the inability to invest in higher yielding securities.

Interest Rate Risk. Fixed income securities may be subject to volatility due to changes in interest rates. The value of fixed-income securities may decline when interest rates go up or increase when interest rates go down. The interest earned on fixed-income securities may decline when interest rates go down or increase when interest rates go up. Duration is a measure of interest rate risk that indicates how price-sensitive a bond is to changes in interest rates. Longer-term and lower coupon bonds tend to be more sensitive to changes in interest rates. For example, a bond with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%. Changing interest rates may have unpredictable effects on markets, may result in heightened market volatility, and could negatively impact the Portfolio’s performance. Any future changes in monetary policy made by central banks and/or their governments are likely to affect the level of interest rates.

Issuer Risk. The value of a security may decline for a number of reasons directly related to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

Market Risk. The Portfolio’s share price or the market as a whole can decline for many reasons or be adversely affected by a number of factors, including, without limitation: weakness in the broad market, a particular industry, or specific holdings; adverse political, regulatory or economic developments in the United States or abroad; changes in investor psychology; heavy institutional selling; military confrontations, war, terrorism and other armed conflicts, disease/virus outbreaks and epidemics; recessions; taxation and international tax treaties; currency, interest rate and price fluctuations; and other

conditions or events. In addition, the subadviser’s assessment of securities held in the Portfolio may prove incorrect, resulting in losses or poor performance even in a rising market.

Management Risk. The Portfolio is subject to management risk because it is an actively-managed investment portfolio. The Portfolio’s portfolio managers apply investment techniques and risk analyses in making investment decisions, but there can be no guarantee that these decisions or the individual securities selected by the portfolio managers will produce the desired results.

Mortgage- and Asset-Backed Securities Risk. The characteristics of mortgage-backed and asset-backed securities differ from traditional fixed income securities. Mortgage-backed securities are subject to “prepayment risk” and “extension risk.” Prepayment risk is the risk that, when interest rates fall, certain types of obligations will be paid off by the obligor more quickly than originally anticipated and the Portfolio may have to invest the proceeds in securities with lower yields. Extension risk is the risk that, when interest rates rise, certain obligations will be paid off by the obligor more slowly than anticipated, causing the value of these securities to fall. Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain mortgage-backed and asset-backed securities. Mortgage-backed and asset-backed securities are also subject to credit risk.

U.S. Government Obligations Risk. U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government and generally have negligible credit risk. Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government.

Affiliated Fund Rebalancing Risk. The Portfolio may be an investment option for other mutual funds for which SunAmerica Asset Management, LLC (“SunAmerica”) serves as investment adviser that are managed as “funds of funds.” From time to time, the Portfolio may experience relatively large redemptions or investments due to the rebalancing of a fund of funds. In the event of such redemptions or investments, the Portfolio could be required to sell securities or to invest cash at a time when it is not advantageous to do so.

Performance Information

The following bar chart illustrates the risks of investing in the Portfolio by showing changes in the Portfolio’s performance from calendar year to calendar year and the table compares the Portfolio’s average annual returns to

SunAmerica Series Trust

- 4 -

SA MFS Total Return Portfolio

those of the S&P 500® Index (a broad-based securities market index) and a blended index. The blended index consists of 40% Bloomberg U.S. Aggregate Bond Index and 60% S&P 500® Index (the “Blended Index”). The Blended Index is relevant to the Portfolio because it has characteristics similar to the Portfolio’s investment strategies. Fees and expenses incurred at the contract level are not reflected in the bar chart or table. If these amounts were reflected, returns would be less than those shown. Of course, past performance is not necessarily an indication of how the Portfolio will perform in the future.

(Class 1 Shares)

During the period shown in the bar chart:

Highest Quarterly Return:	June 30, 2020	12.01%
Lowest Quarterly Return:	March 31, 2020	-14.34%
Year to Date Most Recent Quarter:	March 31, 2025	2.77%

Average Annual Total Returns (For the periods ended December 31, 2024)

	1 Year	5 Years	10 Years
Class 1 Shares	7.64%	6.03%	6.36%
Class 2 Shares	7.45%	5.87%	6.19%
Class 3 Shares	7.35%	5.77%	6.09%
S&P 500® Index (reflects no deduction for fees, expenses or taxes)	25.02%	14.53%	13.10%
Blended Index	15.04%	8.67%	8.52%

Investment Adviser

The Portfolio’s investment adviser is SunAmerica.

The Portfolio is subadvised by Massachusetts Financial Services Company.

Portfolio Managers

Name and Title	Portfolio Manager of the Portfolio Since
Steven R. Gorham Investment Officer	2003
Alexander M. Mackey Investment Officer	2019
Joshua P. Marston Investment Officer	2008
Johnathan Munko Investment Officer	2019

Purchases and Sales of Portfolio Shares

Shares of the Portfolios may only be purchased or redeemed through Variable Contracts offered by the separate accounts of participating life insurance companies and by other portfolios of the Trust and Seasons Series Trust. Shares of a Portfolio may be purchased and redeemed each day the New York Stock Exchange is open, at the Portfolio’s net asset value determined after receipt of a request in good order.

The Portfolios do not have any initial or subsequent investment minimums. However, your insurance company may impose investment or account minimums. Please consult the prospectus (or other offering document) for your Variable Contract which may contain additional information about purchases and redemptions of Portfolio shares.

Tax Information

The Portfolios will not be subject to U.S. federal income tax so long as they qualify as regulated investment companies and distribute their income and gains each year to their shareholders. However, contractholders may be subject to U.S. federal income tax (and a U.S. federal Medicare tax of 3.8% that applies to net investment income, including taxable annuity payments, if applicable) upon withdrawal from a Variable Contract. Contractholders should consult the prospectus (or other offering document) for the Variable Contract for additional information regarding taxation.

SunAmerica Series Trust

- 5 -