Summary Prospectus by Investment Company - Form 497K

September 30, 2024

SUMMARY PROSPECTUS

SIIT Screened World Equity Ex-US Fund (SSEAX)

Class A

Before you invest, you may want to review the Fund's Prospectus, which contains information about the Fund and its risks. You can find the Fund's Prospectus and other information about the Fund, including the Fund's Statement of Additional Information and annual and semi-annual reports, online at seic.com/fundprospectuses. You can also get this information at no cost by dialing 1-800-DIAL-SEI. The Fund's Prospectus and Statement of Additional Information, dated September 30, 2024, as may be supplemented from time to time, are incorporated by reference into this Summary Prospectus and may be obtained, free of charge, at the website or phone number noted above.

seic.com

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Investment Goal

Capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table and examples below.

ANNUAL FUND OPERATING EXPENSES

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 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 Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

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 122% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Screened World Equity Ex-US Fund will invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in equity securities of foreign companies of various capitalization ranges. These securities may include common stocks, preferred stocks, depositary receipts, warrants, exchange-traded funds (ETFs) that track an international ex-US equity index, derivative instruments (principally futures and forward contracts) whose value is based on an international equity index or an underlying international equity security or basket of international equity securities and investment companies whose portfolios are designed to correlate with a portfolio of international equity securities.

Potential investments for the Fund are first assessed for financial soundness and then evaluated according to the Fund's social criteria (including "BDS" criteria, as described below). The Fund will invest in securities of foreign issuers located in developed and emerging market countries but will avoid investing in companies that have been identified as directly or indirectly benefiting the governments of countries that support terrorism, genocide or human rights abuses. This includes companies that pay royalties, such as those on oil or mining, to these governments and companies that help provide a stable economic environment that supports the government in its oppressive policies by having substantial operations or customers in the country. The Fund will also avoid investing in companies that have been identified as having adopted or implemented a "Pro-BDS" stance. "BDS" refers to the Palestinian-led movement promoting boycotts, divestments and economic sanctions against Israel. Accordingly, the Fund will maintain an "Anti-BDS" approach.

An independent compliance support organization will identify a list of issuers that have been identified as failing to meet the Fund's social criteria (including issuers that have a "Pro-BDS" stance). The list will be developed using information gathered from a variety of sources, such as government agencies, trade journals, direct company contacts and industry and regional publications. The Sub-Advisers will then rely on this list when determining what companies to avoid investing in. Additionally, a Sub-Adviser will promptly liquidate a position that no longer complies with the social criteria (including positions in issuers that have a "Pro-BDS" stance). The Adviser reserves the right to modify the Fund's social criteria from time to time in response to world events, such as changes in the governments that support terrorism, genocide or human rights abuses. All social criteria may be changed without

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shareholder approval. The Fund's Anti-BDS approach has been adopted to enable investment in the Fund by institutional investors that seek to support Israel or oppose the BDS movement in their investment implementation. This Fund policy is for the benefit of such investors and not meant as a formal representation of SEI's official corporate policy or position on the issue of BDS.

The Fund will not invest more than 35% of its assets in the common stocks or other equity securities of issuers located in emerging market countries. The Fund may also, to a lesser extent, invest in swaps on securities for risk management purposes or as part of its investment strategies. The Fund's benchmark is the MSCI All Country World Ex-U.S. Net Index (net of dividends). The Fund is expected to have an absolute return and risk profile similar to the international equity ex-US market. The Fund is diversified as to issuers, market capitalization, industry and country.

The Fund uses a multi-manager approach, relying upon a number of sub-advisers (each, a Sub-Adviser and collectively, the Sub-Advisers) with differing investment strategies to manage portions of the Fund's portfolio under the general supervision of SEI Investments Management Corporation (SIMC or the Adviser). Due to its investment strategy, the Fund may buy and sell securities frequently.

One or more Sub-Advisers may implement a long/short equity investment strategy by investing in securities believed to offer capital appreciation opportunities while also attempting to take advantage of an anticipated decline in the price of a company. A long/short equity investment strategy takes (i) long positions with respect to investments that the Sub-Adviser believes to be undervalued relative to their potential increase in price, and (ii) short positions (including through derivative instruments, such as swaps) with respect to investments that the Sub-Adviser believes to be overvalued and likely to decrease in price. A long/short equity investment strategy seeks returns from strong security selection on both the long and short sides. These long and short positions may be completely unrelated.

The Sub-Advisers may seek to enhance the Fund's return by actively managing the Fund's foreign currency exposure. In managing the Fund's currency exposure, the Sub-Advisers may buy and sell currencies (i.e., take long or short positions) using derivatives, principally foreign currency forward contracts, options and futures. The Fund may take long and short positions in foreign currencies in excess of the value of the Fund's assets denominated in a particular currency or when the Fund does not own assets denominated in that currency. The Fund may also engage in currency transactions in an attempt to take advantage of certain inefficiencies in the currency exchange market, to increase their exposure to a foreign currency or to shift exposure to foreign currency fluctuations from one currency to another.

The Fund may also invest in futures contracts and forward contracts for hedging purposes, including to seek to manage the Fund's currency exposure to foreign securities and mitigate the Fund's overall risk.

Principal Risks

Market Risk - The risk that the market value of a security may move up and down, sometimes rapidly and unpredictably. Market risk may affect a single issuer, an industry, a sector or the equity market as a whole. Equity markets may decline significantly in response to adverse issuer, political, regulatory, market, economic or other developments that may cause broad changes in market value, public perceptions concerning these developments, and adverse investor sentiment or publicity. Similarly, environmental and public health risks, such as natural disasters, epidemics, pandemics or widespread fear that such events may occur, may impact markets adversely and cause market volatility in both the short- and long-term.

Foreign Investment/Emerging Markets Risk - The risk that non-U.S. securities may be subject to additional risks due to, among other things, political, social and economic developments abroad, currency movements, and different legal, regulatory, tax, accounting and audit environments. These additional risks may be heightened with respect to emerging market countries because political turmoil and rapid changes in economic conditions are more likely to occur in these countries. Investments in emerging markets are subject to the added risk that information in emerging market investments may be unreliable or outdated due to differences in regulatory, accounting or auditing and financial record keeping standards, or because less information about emerging market investments is publicly available. In addition, the rights and remedies associated with emerging market investments may be different than investments in developed markets. A lack of reliable information, rights and remedies increase the risks of investing in emerging markets in comparison to more developed markets. In addition, periodic U.S. Government restrictions on investments in issuers from certain foreign countries may require the Fund to sell such investments at inopportune times, which could result in losses to the Fund.

Social Investment Criteria Risk - The Fund's portfolio is subject to certain social investment criteria, including its anti-BDS approach. As a result, the Sub-Advisers will avoid purchasing certain securities for social reasons when it is otherwise economically advantageous to purchase those securities or may sell certain securities for social reasons when it is otherwise economically advantageous to hold those securities. In general, the application of the Fund's social investment criteria may affect the Fund's exposure to certain industries, sectors and geographic areas, which may affect the financial performance of the Fund, positively or negatively, depending on whether these industries or sectors are in or out of favor.

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Large Capitalization Risk - The risk that 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 rates of successful smaller companies.

Small and Medium Capitalization Risk - The risk that small and medium capitalization companies in which the Fund may invest may be more vulnerable to adverse business or economic events than larger, more established companies. In particular, small and medium capitalization companies may have limited product lines, markets and financial resources and may depend upon a relatively small management group. Therefore, small capitalization and medium capitalization stocks may be more volatile than those of larger companies. Small capitalization and medium capitalization stocks may be traded over-the-counter (OTC). OTC stocks may trade less frequently and in smaller volume than exchange listed stocks and may have more price volatility than that of exchange-listed stocks.

Investment Style Risk - The risk that equity securities of developed and emerging market countries may underperform other segments of the equity markets or the equity markets as a whole.

Preferred Stock Risk - Preferred stock represents an equity or ownership interest in an issuer that pays dividends at a specified rate and that has precedence over common stock in the payment of dividends. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of bonds take precedence over the claims of those who own preferred and common stock.

Depositary Receipts Risk - Depositary receipts, such as American Depositary Receipts, are certificates evidencing ownership of shares of a foreign issuer that are issued by depositary banks and generally trade on an established market. Depositary receipts are subject to many of the risks associated with investing directly in foreign securities, including, among other things, political, social and economic developments abroad, currency movements and different legal, regulatory, tax, accounting and audit environments.

Warrants Risk - Warrants are instruments that entitle the holder to buy an equity security at a specific price for a specific period of time. Warrants may be more speculative than other types of investments. The price of a warrant may be more volatile than the price of its underlying security, and a warrant may offer greater potential for capital appreciation as well as capital loss. A warrant ceases to have value if it is not exercised prior to its expiration date.

Exchange-Traded Funds Risk - The risks of owning shares of an ETF generally reflect the risks of owning the underlying securities the ETF is designed to track, although lack of liquidity in an ETF could result in its value being more volatile than the underlying portfolio securities. When the Fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF's expenses.

Derivatives Risk - The Fund's use of futures contracts, forwards contracts, options and swaps is subject to market risk, leverage risk, correlation risk and liquidity risk. Leverage risk and liquidity risk are described below and market risk is described above. Many OTC derivative instruments will not have liquidity beyond the counterparty to the instrument. Correlation risk is the risk that changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index. The Fund's use of forward contracts, options and swaps is also subject to credit risk and valuation risk. Credit risk is described below. Valuation risk is the risk that the derivative may be difficult to value and/or valued incorrectly. Each of these risks could cause the Fund to lose more than the principal amount invested in a derivative instrument. Some derivatives have the potential for unlimited loss, regardless of the size of the Fund's initial investment. The other parties to certain derivative contracts present the same types of credit risk as issuers of fixed income securities. The Fund's use of derivatives may also increase the amount of taxes payable by shareholders. Both U.S. and non-U.S. regulators have adopted and implemented regulations governing derivatives markets, the ultimate impact of which remains unclear.

Long/Short Risk - The Fund seeks long exposure to certain financial instruments and short exposure to certain other financial instruments. There is no guarantee that the returns on the Fund's long or short positions will produce positive returns and the Fund could lose money if either or both the Fund's long and short positions produce negative returns.

Currency Risk - As a result of the Fund's investments in securities denominated in, and/or receiving revenues in, foreign currencies, the Fund will be subject to currency risk. Currency risk is the risk that foreign currencies will decline in value relative to the U.S. dollar or, in the case of hedging positions, that the U.S. dollar will decline in value relative to the currency hedged. In either event, the dollar value of an investment in the Fund would be adversely affected. Due to the Fund's active positions in currencies, it will be subject to the risk that currency exchange rates may fluctuate in response to, among other things, changes in interest rates, intervention (or failure to intervene) by U.S. or foreign governments, central banks or supranational entities, or by the imposition of currency controls or other political developments in the United States or abroad.

Liquidity Risk - The risk that certain securities may be difficult or impossible to sell at the time and the price that the Fund would like. The Fund may have to lower the price of the security, sell other securities instead or forego an investment opportunity, any of which could have a negative effect on Fund management or performance.

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Leverage Risk - The Fund's use of derivatives may result in the Fund's total investment exposure substantially exceeding the value of its portfolio securities and the Fund's investment returns depending substantially on the performance of securities that the Fund may not directly own. The use of leverage can amplify the effects of market volatility on the Fund's share price and may also cause the Fund to liquidate portfolio positions when it would not be advantageous to do so in order to satisfy its obligations. The Fund's use of leverage may result in a heightened risk of investment loss.

Credit Risk - The risk that the issuer of a security or the counterparty to a contract will default or otherwise become unable to honor a financial obligation.

Portfolio Turnover Risk - Due to its investment strategy, the Fund may buy and sell securities frequently. This may result in higher transaction costs and taxes subject to ordinary income tax rates as opposed to more favorable capital gains rates, which may affect the Fund's performance.

Investing in the Fund involves risk, and there is no guarantee that the Fund will achieve its investment goal. You could lose money on your investment in the Fund, just as you could with other investments. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance Information

The bar chart and the performance table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year for the past ten calendar years, and by showing how the Fund's average annual returns for 1, 5 and 10 years, and since the Fund's inception compare with those of a broad measure of market performance. The performance information shown is based on a full calendar year. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. For current performance information, please call 1-800-DIAL-SEI.

Average Annual Total Returns (for the periods ended December 31, 2023)

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Management

Investment Adviser and Portfolio Manager. SEI Investments Management Corporation

Sub-Advisers and Portfolio Managers.

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Purchase and Sale of Fund Shares

The Fund's minimum investment requirements for Class A Shares are: (a) that you must be an Eligible Investor (i.e., institutions or other SIMC advisory clients that have entered into an investment management agreement with SIMC or institutional investors, employee benefit plans and other similar entities purchasing through approved intermediaries); and (b) that your minimum initial investment must be $100,000, with minimum subsequent investments of $1,000, which may be waived at the discretion of SIMC. You may purchase and redeem shares of the Fund on any day that the New York Stock Exchange (NYSE) is open for business (a Business Day). You may sell your Fund shares by contacting your authorized financial institution or intermediary directly. Authorized financial institutions and intermediaries may redeem Fund shares on behalf of their clients by contacting the Fund's transfer agent (the Transfer Agent) or the Fund's authorized agent, using certain SEI Investments Company (SEI) or third party systems or by calling 1-800-858-7233, as applicable.

Tax Information

The distributions made by the Fund are generally taxable and will be taxed as qualified dividend income, ordinary income or capital gains. If you are investing through a tax-deferred arrangement, such as a 401(k) plan or individual retirement account, you will generally not be subject to federal taxation on Fund distributions until you begin receiving distributions from your tax-deferred arrangement. You should consult your tax advisor regarding the rules governing your tax-deferred arrangement.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase Fund shares through a broker-dealer or other financial intermediary, such as a bank, the Fund and its related companies 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 salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.