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Summary Prospectus

May 1, 2025

SunAmerica Series Trust

SA Large Cap Growth Index Portfolio

(Class 1 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 investment results that correspond with the performance of the S&P 500® Growth Index.

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 3
Management Fees	0.30%	0.30%
Service (12b-1) Fees	None	0.25%
Other Expenses	0.06%	0.06%
Total Annual Portfolio Operating Expenses Before Fee Waivers and/ or Expense Reimbursements	0.36%	0.61%
Fee Waivers and/or Expense Reimbursements1	0.01%	0.01%
Total Annual Portfolio Operating Expenses After Fee Waivers and/or Expense Reimbursements1	0.35%	0.60%

Pursuant to an Expense Limitation Agreement, SunAmerica Asset Management, LLC (“SunAmerica” or the “Adviser”) has contractually

agreed to waive its fees and/or reimburse expenses to the extent that the Total Annual Portfolio Operating Expenses of Class 1 and Class 3 shares exceed 0.35% and 0.60%, respectively, of the Portfolio’s average daily net assets. For purposes of the Expense Limitation Agreement, “Total Annual Portfolio Operating Expenses” shall not include extraordinary expenses (i.e., expenses that are unusual in nature and infrequent in occurrence, such as litigation), or acquired fund fees and expenses, brokerage commissions and other transactional expenses relating to the purchase and sale of portfolio securities, interest, taxes and governmental fees, and other expenses not incurred in the ordinary course of business of SunAmerica Series Trust (the “Trust”) on behalf of the Portfolio. Any waivers and/or reimbursements made by SunAmerica with respect to the Portfolio are subject to recoupment from the Portfolio within two years after the occurrence of the waivers and/or reimbursements, provided that the recoupment does not cause the expense ratio of the share class to exceed the lesser of (a) the expense limitation in effect at the time the waivers and/or reimbursements occurred, or (b) the current expense limitation of that share class. This agreement may be modified or discontinued prior to April 30, 2026, only with the approval of the Board of Trustees of 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 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

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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	$36	$115	$201	$455
Class 3	61	194	339	761

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 58% of the average value of its portfolio.

Principal Investment Strategies of the Portfolio

The Portfolio seeks to provide investment results that correspond with the performance of the S&P 500® Growth Index (the “Index”). The Index measures the performance of large-cap U.S. dollar-denominated U.S. equities as determined using three factors: sales growth, the ratio of earnings change to price, and momentum.

The subadviser primarily seeks to achieve the Portfolio’s objective by investing in all or substantially all of the stocks included in the Index, a strategy known as “replication.” The subadviser may, however, utilize an “optimization” strategy in circumstances in which replication is difficult or impossible, such as if the Portfolio has low asset levels and cannot replicate, to reduce trading costs or to gain exposure to securities that the Portfolio cannot access directly. The goal of optimization is to select stocks which ensure that characteristics such as industry weightings, average market capitalizations and fundamental characteristics (e.g., price-to-book, price-to-earnings, debt-to-asset ratios and dividend yields) closely approximate those of the Index. Stocks not in the Index may be held before or after changes in the composition of the Index or if they have characteristics similar to stocks in the Index. Under normal circumstances, the Portfolio invests substantially all, but at least 80%, of its net assets in securities included in the Index or in securities that the subadviser determines have economic characteristics that are comparable to the economic characteristics of securities included in the Index, including derivatives, such as contracts for difference. The Portfolio will not concentrate, except to approximately the same extent as the Index may concentrate, in the securities of any industry. It is not anticipated, however, that the Portfolio

will, under normal circumstances, be concentrated in the securities of any industry.

Because the Portfolio will generally not hold all of the stocks included in the Index, and because the Portfolio has expenses and the Index does not, the Portfolio will not duplicate the Index’s performance precisely. However, the subadviser believes there should be a close correlation between the Portfolio’s performance and that of the Index in both rising and falling markets.

The Portfolio may become non-diversified (which means that it can invest a greater percentage of its assets in the securities of fewer issuers than can a diversified fund), solely as a result of a change in the relative market capitalization or index weighting of one or more of the Index constituents.

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.

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.

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Consequently, if earnings expectations are not met, the market price of growth stocks will often decline more than other stocks.

Failure to Match Index Performance Risk. The ability of the Portfolio to match the performance of the Index may be affected by, among other things, changes in securities markets, the manner in which performance of the Index is calculated, changes in the composition of the Index, the amount and timing of cash flows into and out of the Portfolio, commissions, portfolio expenses, and any differences in the pricing of securities by the Portfolio and the Index. When the Portfolio employs an “optimization” strategy, the Portfolio is subject to an increased risk of tracking error, in that the securities selected in the aggregate for the Portfolio may perform differently than the underlying index.

“Passively Managed” Strategy Risk. The Portfolio will not deviate from its strategy, except to the extent necessary to comply with federal tax laws. If the Portfolio’s strategy is unsuccessful, the Portfolio will not meet its investment goal. Because the Portfolio will not use certain techniques available to other mutual funds to reduce stock market exposure, the Portfolio may be more susceptible to general market declines than other funds.

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.

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.

Non-Diversification Risk. In order to replicate the composition of the Index, the Portfolio’s total assets may at times be invested in multiple issuers representing more than 5% of the Portfolio’s total assets. As a result, the Portfolio may, from time to time, become “non-diversified.” A non-diversified fund may invest a larger portion of assets in the securities of a single company than a diversified fund. By concentrating in a smaller number of issuers, the Portfolio’s risk may be increased because the effect of each security on the Portfolio’s performance is greater.

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

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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) and the S&P 500® Growth 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.

BlackRock Investment Management, LLC assumed subadvisory duties of the Portfolio on April 30, 2025. Prior to April 30, 2025, SunAmerica managed the Portfolio.

(Class 1 Shares)

During the period shown in the bar chart:

Highest Quarterly Return:	June 30, 2020	25.95%
Lowest Quarterly Return:	June 30, 2022	-20.83%
Year to Date Most Recent Quarter:	March 31, 2025	-8.56%

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

	1 Year	5 Years	Since Inception	Inception Date
Class 1 Shares	35.68%	16.60%	16.22%	5/1/2018
Class 3 Shares	35.31%	16.30%	15.93%	5/1/2018
S&P 500® Index (reflects no deduction for fees, expenses or taxes)	25.02%	14.53%	14.64%
S&P 500® Growth Index (reflects no deduction for fees, expenses or taxes)	36.07%	17.09%	16.85%

Investment Adviser

The Portfolio’s investment adviser is SunAmerica.

The Portfolio is subadvised by BlackRock Investment Management, LLC.

Portfolio Managers

Name and Title	Portfolio Manager of the Portfolio Since
Paul Whitehead Managing Director	2025
Jennifer Hsui, CFA Managing Director	2025
Peter Sietsema, CFA Director	2025
Matt Waldron, CFA Managing Director	2025
Steven White Director	2025

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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