SIIT SMALL MID CAP EQUITY FUND

SMALL/MID CAP EQUITY FUND

Investment Goal

Long-term capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold Fund shares.

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	SIIT SMALL MID CAP EQUITY FUND SIIT SMALL MID CAP EQUITY FUND - CLASS A
Management Fees	0.65%
Distribution (12b-1) Fees	none
Other Expenses	0.07%
Total Annual Fund Operating Expenses	0.72%

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 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 and returns may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
SIIT SMALL MID CAP EQUITY FUND | SIIT SMALL MID CAP EQUITY FUND - CLASS A | USD ($)	74	230	401	894

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 111% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Small/Mid Cap Equity Fund will invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in equity securities (including common and preferred stocks) of small and medium-sized companies, exchange-traded funds (ETFs) based on small and medium-sized capitalization indexes and securities of real estate investment trusts (REITs). The Fund will invest primarily in common stocks of U.S. companies with market capitalizations in the range of companies in the Russell 2500 Index (between $7.44 million and $16.93 billion as of July 31, 2020) at the time of purchase. The market capitalization range and the composition of the Russell 2500 Index

are subject to change. The Fund's investments in equity securities may include, to a lesser extent, securities of large capitalization companies.

The Fund uses a multi-manager approach, relying upon one or more sub-advisers (each, a Sub-Adviser and collectively, the Sub-Advisers) with differing investment philosophies to manage portions of the Fund's portfolio under the general supervision of SEI Investments Management Corporation (SIMC or the Adviser). Each Sub-Adviser, in managing its portion of the Fund's assets, generally applies a growth-oriented, a value-oriented or a blended approach to selecting investments. Growth-oriented managers generally select stocks they believe have attractive growth and appreciation potential in light of such characteristics as revenue and earnings growth, expectations from sell-side analysts and relative valuation, while value-oriented managers generally select stocks they believe are attractively valued in light of fundamental characteristics such as earnings, capital structure and/or return on invested capital. Due to its investment strategy, the Fund may buy and sell securities frequently.

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.

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 smaller and medium capitalization securities may underperform other segments of the equity market 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.

Exchange-Traded Funds (ETFs) 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.

REITs Risk — REITs are trusts that invest primarily in commercial real estate or real estate-related loans. The Fund's investments in REITs will be subject to the risks associated with the direct ownership of real estate. Risks commonly associated with the direct ownership of real estate include fluctuations in the

value of underlying properties, defaults by borrowers or tenants, changes in interest rates and risks related to general or local economic conditions. Some REITs may have limited diversification and may be subject to risks inherent in financing a limited number of properties.

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.

Portfolio Turnover Risk — Due to its investment strategy, the Fund may buy and sell securities frequently. This may result in higher transaction costs and additional capital gains tax liabilities, 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 full calendar years. 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.

Best Quarter: 14.74% (12/31/10)
Worst Quarter: -21.44% (09/30/11)
The Fund's total return from January 1, 2020 to June 30, 2020 was -13.36%.

Average Annual Total Returns (for the periods ended December 31, 2019)

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. In some cases, the Fund's return after taxes may exceed the Fund's return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.

Average Annual Returns - SIIT SMALL MID CAP EQUITY FUND	Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
SIIT SMALL MID CAP EQUITY FUND - CLASS A	Return Before Taxes	25.56%	7.23%	11.36%	8.62%	Dec. 15, 2003
After Taxes on Distributions | SIIT SMALL MID CAP EQUITY FUND - CLASS A	Return After Taxes on Distributions	23.63%	3.91%	8.52%	6.50%
After Taxes on Distributions and Sale of Fund Shares | SIIT SMALL MID CAP EQUITY FUND - CLASS A	Return After Taxes on Distributions and Sale of Fund Shares	16.45%	4.86%	8.53%	6.45%
Russell 2500 Index Return (reflects no deduction for fees, expenses or taxes)	Russell 2500 Index Return (reflects no deduction for fees, expenses or taxes)	27.77%	8.93%	12.58%	9.58%	Dec. 15, 2003