Summary Prospectus
May 1, 2025
SunAmerica Series Trust
SA MFS Massachusetts Investors Trust 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 growth of income and long term growth and appreciation.
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
0.69%
0.69%
0.69%
Service (12b-1) Fees
None
0.15%
0.25%
Other Expenses
0.03%
0.03%
0.03%
Total Annual Portfolio
Operating Expenses
Before Fee Waivers and/
or Expense
Reimbursements
0.72%
0.87%
0.97%
Fee Waivers and/or
Expense
Reimbursements1
0.04%
0.04%
0.04%
 
Class 1
Class 2
Class 3
Total Annual Portfolio
Operating Expenses
After Fee Waivers and/
or Expense
Reimbursements1
0.68%
0.83%
0.93%
1
Pursuant to an Advisory Fee Waiver Agreement, effective through April 30, 2026, SunAmerica Asset Management, LLC (“SunAmerica”) is contractually obligated to waive a portion of its advisory fee on an annual basis with respect to the Portfolio so that the advisory fee rate payable by the Portfolio to SunAmerica is equal to 0.66% of the Portfolio’s average daily net assets on the first $600 million, 0.61% of the Portfolio’s average daily net assets on the next $900 million, and 0.56% of the Portfolio’s average daily net assets over $1.5 billion. SunAmerica may not recoup any advisory fees waived with respect to the Portfolio pursuant to the Advisory Fee Waiver Agreement. This agreement may be modified or discontinued prior to April 30, 2026 only with the approval of the Board of Trustees of SunAmerica Series Trust (the “Trust”), including a majority of the trustees who are not “interested persons” of the Trust as defined in the Investment Company Act of 1940, as amended.
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
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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
$69
$226
$397
$891
Class 2
85
274
478
1,069
Class 3
95
305
532
1,186
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 24% of the average value of its portfolio.
Principal Investment Strategies of the Portfolio
The Portfolio attempts to achieve its goal by investing, under normal market conditions, at least 65% of its assets in equity securities. Equity securities include common stocks, preferred stocks, securities convertible into stocks, and depositary receipts for such securities. The Portfolio may invest up to 25% of its net assets in foreign securities.
In selecting investments for the Portfolio, the subadviser is not constrained by any particular investment style. The subadviser may invest the Portfolio’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies), in the stocks of companies it believes are undervalued compared to their perceived worth (value companies), or in a combination of growth and value companies. While the Portfolio may invest its assets in securities of companies of any size, the Portfolio primarily invests in securities of companies with large capitalizations.
The subadviser normally invests the Portfolio’s assets across different industries and sectors, but the subadviser may invest a significant percentage of the Portfolio’s assets in a single industry or sector.
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 their
potential in light of their financial condition, and market, economic, political, and regulatory conditions. Factors considered may include analysis of an issuer’s earnings, cash flows, competitive position, and management ability. 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 an issuer’s valuation, price and earnings momentum, earnings quality, and other factors 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.
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
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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.
Convertible Securities Risk. The values of the convertible securities in which the Portfolio may invest will 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.
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.
Growth Stock Risk. Growth stocks may lack the dividend yield associated with value stocks that can cushion total return in a bear market. Also, growth stocks normally carry a higher price/earnings ratio than many other stocks. Consequently, if earnings expectations are not met, the market price of growth stocks will often decline more than other stocks.
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.
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.
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.
Affiliated Fund Rebalancing Risk. The Portfolio may be an investment option for other mutual funds for which 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
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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 those of the S&P 500® Index (a broad-based securities market index), which 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
19.67%
Lowest Quarterly
Return:
March 31, 2020
-20.45%
Year to Date Most
Recent Quarter:
March 31, 2025
-2.50%
Average Annual Total Returns (For the periods ended December 31, 2024)  
 
1
Year
5
Years
10
Years
Class 1 Shares
19.65%
11.58%
11.23%
Class 2 Shares
19.49%
11.41%
11.06%
Class 3 Shares
19.35%
11.30%
10.95%
S&P 500® Index (reflects no deduction
for fees, expenses or taxes)
25.02%
14.53%
13.10%
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
Alison O’Neill Mackey
Co-Chief Investment Officer – Equity
Americas
2018
Jude Jason
Investment Officer
June 2021
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.
Payments to Broker-Dealers and
Other Financial Intermediaries
The Portfolios are not sold directly to the general public but instead are offered as an underlying investment option for Variable Contracts and to other portfolios of the Trust and Seasons Series Trust. A Portfolio and its related companies may make payments to the sponsoring
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insurance company (or its affiliates) for distribution and/or other services. These payments may create a conflict of interest as they may be a factor that the insurance company considers in including a Portfolio as an underlying investment option in the Variable Contract. The
prospectus (or other offering document) for your Variable Contract may contain additional information about these payments.
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