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Summary Prospectus

May 1, 2025

SunAmerica Series Trust

SA JPMorgan Ultra-Short Bond 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 goal is current income consistent with liquidity and preservation 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	0.46%	0.46%	0.46%
Service (12b-1) Fees	None	0.15%	0.25%
Other Expenses	0.07%	0.07%	0.07%
Total Annual Portfolio Operating Expenses	0.53%	0.68%	0.78%

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	$54	$170	$296	$665
Class 2	69	218	379	847
Class 3	80	249	433	966

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 118% of the average value of its portfolio.

Principal Investment Strategies of the Portfolio

The Portfolio attempts to achieve its investment goal by investing, under normal circumstances, at least 80% of its net assets in U.S. dollar denominated short-term fixed, variable and floating rate debt. The Portfolio invests primarily in corporate securities, asset-backed securities, mortgage-backed and mortgage-related securities, and high quality money market instruments such as

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commercial paper and certificates of deposit. The Portfolio may also invest in U.S. Treasury securities (including Separate Trading of Registered Interest and Principal of Securities (STRIPS)), securities issued or guaranteed by the U.S. government or its agencies and instrumentalities, securities issued or guaranteed by foreign governments, repurchase agreements, when-issued securities, delayed delivery securities, forward commitments, zero-coupon securities and privately placed securities. All securities will be U.S. dollar-denominated although they may be issued by a foreign corporation or a U.S. affiliate of a foreign corporation, or a foreign government or its agencies and instrumentalities.

Under normal circumstances, the Portfolio maintains a duration of one year or less from the date of settlement, although under certain market conditions such as in periods of significant volatility in interest rates and spreads, the Portfolio’s duration may be longer than one year. Duration is a measure of price sensitivity of a debt security or a portfolio of debt securities to relative changes in interest rates. For instance, a duration of “one” means that a security’s or portfolio’s price would be expected to decrease by approximately 1% with a 1% increase in interest rates (assuming a parallel shift in yield curve).

The Portfolio may invest a significant portion of its assets in mortgage-related and mortgage-backed, as well as restricted securities, at the subadviser’s discretion. The asset-backed securities in which the Portfolio may invest include “sub-prime” securities and collateralized loan obligations (CLOs). The Portfolio may invest in securities of any credit quality, but will invest primarily in investment grade securities.

The Portfolio may use futures contracts in connection with its principal strategies in certain market conditions in order to hedge various investments, for risk management purposes and/or to seek to increase income or gain to the Portfolio.

The Portfolio is not a money market fund and is not subject to the special regulatory requirements (including maturity and credit quality constraints) designed to enable money market funds to maintain a stable share price.

The subadviser allocates the Portfolio’s assets among a range of sectors based on strategic positioning and other tactical considerations. In buying and selling investments for the Portfolio, the subadviser looks for market sectors and individual securities that it believes will perform well over time. The subadviser selects individual securities after performing a risk/reward analysis that includes an evaluation of their characteristics including income, interest rate risk, credit risk and the complex legal and technical structure of the transaction. As part of its

security selection strategy, the subadviser seeks to assess the impact of environmental, social and governance (ESG) factors on many issuers in the universe in which the Portfolio may invest. ESG factors assessed may include, but are not limited to, issues related to the quality and function of the natural environment, such as climate change resilience and greenhouse gas emissions; social issues related to the rights, wellbeing and interests of people and communities, such as discrimination prevention and workplace safety; and governance issues relating to the way companies are managed and overseen, such as board diversity and executive compensation. The subadviser’s assessment is based on an analysis of key opportunities and risks across industries to seek to identify financially material issues with respect to the Fund’s investments in issuers and ascertain key issues that merit engagement with issuers. These assessments may not be conclusive and securities of issuers that may be negatively impacted by such factors may be purchased and retained by the Fund while the Fund may divest or not invest in securities of issuers that may be positively impacted by such factors.

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.

Active Trading Risk. The Portfolio may engage in frequent trading of securities to achieve its investment goal. Active trading may result in high portfolio turnover and correspondingly greater brokerage commissions and other transaction costs, which will be borne directly by the Portfolio and could affect its performance. During periods of increased market volatility, active trading may be more pronounced.

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

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required to sell securities or to invest cash at a time when it is not advantageous to do so.

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.

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.

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. Debt securities backed by an issuer’s taxing authority may be subject to legal limits on the issuer’s power to increase taxes or otherwise raise revenue, or may be dependent on legislative appropriation or government aid. Certain debt securities are backed only by revenues derived from a particular project or source, rather than by an issuer’s taxing authority, and thus may have a greater risk of default.

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

Derivatives Risk. A derivative is any financial instrument whose value is based on, and determined by, another security, index, rate or benchmark (i.e., stock options, futures, caps, floors, etc.). To the extent a derivative contract is used to hedge another position in the Portfolio, the Portfolio will be exposed to the risks associated with hedging described below. To the extent an option, futures contract, swap, or other derivative is used to enhance return, rather than as a hedge, the Portfolio will be directly exposed to the risks of the contract. Unfavorable changes in the value of the underlying security, index, rate or benchmark may cause sudden losses. Gains or losses

from the Portfolio’s use of derivatives may be substantially greater than the amount of the Portfolio’s investment. Certain derivatives have the potential for undefined loss. Derivatives are also associated with various other risks, including market risk, leverage risk, hedging risk, counterparty risk, valuation risk, regulatory risk, illiquidity risk and interest rate fluctuations risk. The primary risks associated with the Portfolio’s use of derivatives are market risk, counterparty risk and hedging risk.

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.

Floating Rate Securities Risk. Floating rate securities reset whenever there is a change in a specified index rate. In most cases, these reset provisions reduce the impact of changes in market interest rates on the value of the security. However, the value of these securities may decline if their interest rates do not rise as much, or as quickly, as other interest rates. Conversely, these securities will not generally increase in value if interest rates decline. The absence of an active market for these securities could make it difficult for the Portfolio to dispose of them if the issuer defaults.

Variable and floating rate obligations normally will involve industrial development or revenue bonds which provide that the rate of interest is set as a specific percentage of a designated base rate, such as rates on Treasury Bonds or Bills or the prime rate at a major commercial bank, and that a bondholder can demand payment of the obligations on behalf of a Portfolio on short notice at par plus accrued interest, which amount may be more or less than the amount the bondholder paid for them. The maturity of floating or variable rate obligations (including participation interests therein) is deemed to be the longer of (i) the notice period required before a Portfolio is entitled to receive payment of the obligation upon demand, or (ii) the

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period remaining until the obligation’s next interest rate adjustment. If not redeemed by a Portfolio through the demand feature, the obligations mature on a specified date which may range up to thirty years from the date of issuance.

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.

Illiquidity Risk. An illiquid investment is any investment that the Portfolio reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without the sale or disposition significantly changing the market value of the investment. Illiquidity risk exists when particular investments are difficult to sell. Although most of the Portfolio’s investments must be liquid at the time of investment, investments may lack liquidity after purchase by the Portfolio, particularly during periods of market turmoil. When the Portfolio holds illiquid investments, its investments may be harder to value, especially in changing markets, and if the Portfolio is forced to sell these investments to meet redemption requests or for other cash needs, the Portfolio may suffer a loss. In addition, when there is illiquidity in the market for certain investments, the Portfolio, due to limitations on illiquid investments, may be unable to achieve its desired level of exposure to a certain sector. When there is little or no active trading market for specific types of securities, it can become more difficult to sell the securities at or near their perceived value. In such a market, the value of such securities and the Portfolio’s share price may fall dramatically.

Income Risk. The ability of the Portfolio’s equity securities to generate income generally depends on the earnings and the continuing declaration of dividends by

the issuers of such securities. The interest income on debt securities generally is affected by prevailing interest rates, which can vary widely over the short- and long-term. If dividends are reduced or discontinued or interest rates drop, distributions to shareholders from the Portfolio may drop as well.

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.

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.

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.

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Mortgage- and Asset-Backed Securities Risk. Mortgage- and asset-backed securities represent interests in “pools” of mortgages or other assets, including consumer loans or receivables held in trust. The characteristics of these mortgage-backed and asset-backed securities differ from traditional fixed-income securities. Mortgage-backed securities are subject to prepayment risk (described below) and “extension risk.” 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 securities. These securities also are subject to risk of default on the underlying mortgage, particularly during periods of economic downturn.

Repurchase Agreements Risk. Repurchase agreements are agreements in which the seller of a security to the Portfolio agrees to repurchase that security from the Portfolio at a mutually agreed upon price and date. Repurchase agreements carry the risk that the counterparty may not fulfill its obligations under the agreement. This could cause the Portfolio’s income and the value of the Portfolio to decline.

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. Fixed income securities may be subject to volatility due to changes in interest rates.

Money Market Securities Risk. An investment in the Portfolio is subject to the risk that the value of its investments in high-quality short-term obligations (“money market securities”) may be subject to changes in interest rates, changes in the rating of any money market security and in the ability of an issuer to make payments of interest and principal.

Privately Placed Securities Risk. A Portfolio may have the ability, as previously listed in its investment strategy, to invest in privately placed securities, which are subject to resale restrictions. These investments are also subject to illiquidity and valuation risk. Privately placed securities are restricted securities and generally cannot be offered for public resale unless registered under the applicable securities laws or are subject to contractual restrictions that may make them difficult to sell. These securities will have the effect of increasing a Portfolio’s level of illiquidity to the extent the Portfolio may be unable to sell or transfer these securities due to restrictions on transfers or on the

ability to find buyers interested in purchasing the securities. The illiquidity of the market, as well as the lack of publicly available information regarding these securities, may also adversely affect the ability to arrive at a fair value for certain securities at certain times and could make it difficult for the Portfolio to sell certain securities.

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.

Zero Coupon Bond Risk. “Zero coupon” bonds are sold at a discount from face value and do not make periodic interest payments. At maturity, zero coupon bonds can be redeemed for their face value. In addition to the risks associated with bonds, since zero coupon bonds do not pay interest, the value of zero coupon bonds may be more volatile than other fixed income securities. Zero coupon bonds may also be subject to greater interest rate risk and credit risk than other fixed income instruments.

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 those of the Bloomberg U.S. Aggregate Bond Index (a broad-based securities market index) and the ICE BofA 3-Month US Treasury Bill Index, which is relevant to the Portfolio because it has characteristics similar to the Portfolio’s investment strategies. The Portfolio’s returns prior to April 29, 2024, as reflected in the bar chart and table, are the returns of the Portfolio when it followed different investment strategies under the name “SA DFA Ultra Short Bond Portfolio.” 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.

Effective April 29, 2024, J.P. Morgan Investment Management Inc. (“JPMorgan”) replaced Dimensional Fund Advisors LP (“DFA”) as subadviser to the Portfolio. Prior to April 29, 2024, DFA served as subadviser. Prior to May 1, 2016, the Portfolio was managed by SunAmerica. Prior to April 15, 2016, BofA Advisors, LLC served as subadviser.

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Performance for periods prior to May 1, 2016 reflects results when the Portfolio was managed as a money market fund.

(Class 1 Shares)

During the period shown in the bar chart:

Highest Quarterly Return:	September 30, 2024	1.65%
Lowest Quarterly Return:	March 31, 2022	-1.25%
Year to Date Most Recent Quarter:	March 31, 2025	1.21%

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

	1 Year	5 Years	10 Years
Class 1 Shares	5.31%	1.58%	1.21%
Class 2 Shares	5.22%	1.44%	1.06%
Class 3 Shares	5.08%	1.35%	0.96%
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)	1.25%	-0.33%	1.35%
ICE BofA 3-Month US Treasury Bill Index (reflects no deduction for fees, expenses or taxes)	5.25%	2.46%	1.77%

Investment Adviser

The Portfolio’s investment adviser is SunAmerica.

The Portfolio is subadvised by JPMorgan.

Portfolio Managers

Name and Title	Portfolio Manager of the Portfolio Since
James McNerny Managing Director	2024
Karl Lohninger Executive Director	2024

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.

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