STATE STREET INSTITUTIONAL INVESTMENT TRUST

State Street Income Fund

Investment Objectives

The investment objective of the State Street Income Fund (the “Fund”) is to seek high current income and preservation of capital.

Fees and Expenses of the Fund

The tables below describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund (“Fund Shares”). You may pay brokerage commissions and other fees to financial intermediaries which are not reflected in the tables and examples below. More information about these and other discounts is available from your financial intermediary (“Financial Intermediary”) and in the “Investing in Funds Shares” section of the Fund's Prospectus.

Shareholder Fees (fees paid directly from your investment)

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	None
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the sale proceeds or the original offering price)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management Fee	0.13%
Distribution and/or Shareholder Service (12b-1) Fees	None
Other Expenses	0.06%
Acquired Fund Fees and Expenses	0.01%
Total Annual Fund Operating Expenses	0.20%

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 sell or hold all of your Fund 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:

1 year	3 years	5 years	10 years
$20	$64	$113	$255

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 32% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund seeks to achieve its investment objective by investing at least 80% of its net assets in debt securities.

securities of comparable quality as determined by SSGA Funds Management, Inc. (the “Adviser” or “SSGA FM”)). The Fund normally has a weighted average effective maturity of approximately five to ten years, but is subject to no limitation with respect to the maturities of the instruments in which it may invest.

The portfolio managers seek to identify debt securities that they believe have desirable characteristics for the Fund such as:

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attractive yields and prices;

•

the potential for capital appreciation; and/or

•

reasonable credit quality.

The portfolio managers may consider selling a security when one of these characteristics no longer applies, when the portfolio managers believe that the valuation has become excessive, or when more attractive alternatives are identified.

The Fund also may invest up to 20% of its net assets in high yield securities (also known as below investment grade bonds or “junk bonds”). The Fund may also invest up to 20% of its net assets in exchange-traded products (“ETPs”), including exchange-traded funds, that provide exposure to such investments, including ETPs that pay fees to the Adviser and its affiliates for management, marketing or other services; mutual funds; and other commingled investments. High yield securities are those rated BB+ or lower by S&P or Ba1 or lower by Moody's (and securities of comparable quality as determined by the Adviser). The Fund also may invest up to 35% of its net assets in foreign (including emerging markets) debt securities, and up to 20% of its net assets in equity securities.

The portfolio managers may also use various types of derivative instruments (such as futures contracts, interest rate and credit default swaps, options and forward contracts) to manage yield, duration (a measure of a bond price's sensitivity to a given change in interest rates) and exposure to credit quality, and to gain or hedge exposure to certain securities, indices or market segments.

The Fund may engage in active and frequent trading of its portfolio securities.

Principal Risks

The Fund is subject to the following principal risks. You could lose money by investing in the Fund. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund's portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund. An investment in the Fund is subject to investment risks, including possible loss of principal, is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation (“FDIC”) or any other government agency. The Fund may not achieve its investment objective. The Fund is not intended to be a complete investment program, but rather is intended for investment as part of a diversified investment portfolio. Investors should consult their own advisers as to the role of the Fund in their overall investment programs.

Market Risk: The Fund's investments are subject to changes in general economic conditions, general market fluctuations and the risks inherent in investment in securities markets. Investment markets can be volatile and prices of investments can change substantially due to various factors including, but not limited to, economic growth or recession, changes in interest rates, inflation, changes in the actual or perceived creditworthiness of issuers, and general market liquidity. The Fund is subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. Local, regional or global events such as war, military conflicts, acts of terrorism, natural disasters, the spread of infectious illness or other public health issues, or other events could have a significant impact on the Fund and its investments.

yield can be low, and the Fund may have a negative yield (i.e., it may lose money on an operating basis). To the extent that interest rates fall, certain underlying obligations may be paid off substantially faster than originally anticipated. If the principal on a debt obligation is prepaid before expected, the prepayments of principal may have to be reinvested in obligations paying interest at lower rates. During periods of falling interest rates, the income received by the Fund may decline. Changes in interest rates will likely have a greater effect on the values of debt securities of longer durations. Returns on investments in debt securities could trail the returns on other investment options, including investments in equity securities. The U.S. Federal Reserve has been engaged in an aggressive campaign to raise interest rates in an effort to combat historically high levels of inflation. Interest rate increases may continue. High levels of inflation and/or a significantly changing interest rate environment can lead to heightened levels of volatility and reduced liquidity. See also “Extension Risk” and “Credit Risk” in the section titled “Additional Information about Investment Objectives, Principal Strategies, and Risks - Additional Information About Risks.”

Management Risk: The Fund is actively managed. The Adviser's judgments about the attractiveness, relative value, or potential appreciation of a particular sector, security, commodity or investment strategy may prove to be incorrect, and may cause the Fund to incur losses. There can be no assurance that the Adviser's investment techniques and decisions will produce the desired results.

Below Investment-Grade Securities Risk: Lower-quality debt securities (“high yield” or “junk” bonds) are considered predominantly speculative, and can involve a substantially greater risk of default than higher quality debt securities. Issuers of lower-quality debt securities may have substantially greater risk of insolvency or bankruptcy than issuers of higher-quality debt securities. They can be illiquid, and their values can have significant volatility and may decline significantly over short periods of time. Lower-quality debt securities tend to be more sensitive to adverse news about the issuer, or the market or economy in general.

Derivatives Risk: Derivative transactions can create investment leverage and may have significant volatility. It is possible that a derivative transaction will result in a much greater loss than the principal amount invested, that changes in the value of a derivative transaction may not correlate perfectly with the underlying asset, and that the Fund may not be able to close out a derivative transaction at a favorable time or price. The counterparty to a derivatives contract may be unable or unwilling to make timely settlement payments, return the Fund's margin, or otherwise honor its obligations. A derivatives transaction may not behave in the manner anticipated by the Adviser or may not have the effect on the Fund anticipated by the Adviser.

Counterparty Risk: The Fund will be subject to credit risk with respect to the counterparties with which the Fund enters into derivatives contracts, repurchase agreements, reverse repurchase agreements, and other transactions. If a counterparty fails to meet its contractual obligations, the Fund may be unable to terminate or realize any gain on the investment or transaction, or to recover collateral posted to the counterparty, resulting in a loss to the Fund. If the Fund holds collateral posted by its counterparty, it may be delayed or prevented from realizing on the collateral in the event of a bankruptcy or insolvency proceeding relating to the counterparty.

Emerging Markets Risk: Risks of investing in emerging markets include, among others, greater political and economic instability, greater volatility in currency exchange rates, less developed securities markets, possible trade barriers, currency transfer restrictions, a more limited number of potential buyers and issuers, an emerging market country's dependence on revenue from particular commodities or international aid, less governmental supervision and regulation, unavailability of currency hedging techniques, differences in auditing and financial reporting standards, less stringent investor protection and disclosure standards, less developed public health systems, and less developed legal systems. There is also the potential for unfavorable action such as expropriation, nationalization, embargo, and acts of war. The securities of emerging market companies may trade less frequently and in smaller volumes than more widely held securities. Market disruptions or substantial market corrections may limit very significantly the liquidity of securities of certain companies in a particular country or geographic region, or of all companies in the country or region. The Fund may be unable to liquidate its positions in such securities at any time, or at a favorable price, in order to meet the Fund's obligations. These risks are generally greater for investments in frontier market countries, which typically have smaller economies or less developed capital markets than traditional emerging market countries.

Equity Investing Risk: The market prices of equity securities owned by the Fund may go up or down, sometimes rapidly or unpredictably. The value of a security may decline for a number of reasons that may directly relate to the issuer and also may decline due to general industry or market conditions that are not specifically related to a particular company. In addition, equity markets tend to move in cycles, which may cause stock prices to fall over short or extended periods of time.

Exchange Traded Products Risk: The Fund is subject to substantially the same risks as those associated with the direct ownership of the securities represented by the ETPs in which it invests. In addition, the shares of certain ETPs may trade at a premium or discount to their intrinsic value (i.e., the market value may differ from the net asset value of an exchange-traded fund's (“ETF”) shares) for a number of reasons. For example, supply and demand for shares of an ETF or market disruptions may cause the market price of the ETF to deviate from the value of the ETF's investments, which may be exacerbated in less liquid markets. The value of an exchange traded note may also differ from the valuation of its reference market due to changes in the issuer's credit rating.

Affiliated ETP Risk: The Adviser may receive management or other fees from the ETPs (“Affiliated ETPs”) in which the Fund may invest, as well as a management fee for managing the Fund. It is possible that a conflict of interest among the Fund and the Affiliated ETPs could affect how the Adviser fulfills its fiduciary duties to the Fund and the Affiliated ETPs. Because the amount of the investment management fees to be retained by the Adviser may differ depending upon the Affiliated ETPs in which the Fund invests, there is a conflict of interest for the Adviser in selecting the Affiliated ETPs. In addition, the Adviser may have an incentive to take into account the effect on an Affiliated ETP in which the Fund may invest in determining whether, and under what circumstances, to purchase or sell shares in that Affiliated ETP. Although the Adviser takes steps to address the conflicts of interest, it is possible that the conflicts could impact the Fund.

Interest Rate Risk: Interest rate risk is the risk that the securities held by a Fund will decline in value because of increases in market interest rates. Duration is a measure used to determine the sensitivity of a security's price to changes in interest rates. Debt securities with longer durations tend to be more sensitive to changes in interest rates, usually making them more volatile than debt securities with shorter durations. For example, the value of a security with a duration of five years would be expected to decrease by 5% for every 1% increase in interest rates. Falling interest rates also create the potential for a decline in a Fund's income and yield. Interest-only and principal-only securities are especially sensitive to interest rate changes, which can affect not only their prices but can also change the income flows and repayment assumptions about those investments. Variable and floating rate securities also generally increase or decrease in value in response to changes in interest rates, although generally to a lesser degree than fixed-rate securities. A substantial increase in interest rates may also have an adverse impact on the liquidity of a security, especially those with longer durations. Changes in governmental policy, including changes in central bank monetary policy, could cause interest rates to rise rapidly, or cause investors to expect a rapid rise in interest rates. This could lead to heightened levels of interest rate, volatility and liquidity risks for the fixed income markets generally and could have a substantial and immediate effect on the values of a Fund's investments. The U.S. Federal Reserve has been engaged in an aggressive campaign to raise interest rates in an effort to combat historically high levels of inflation. Interest rate increases may continue. High levels of inflation and/or a significantly changing interest rate environment can lead to heightened levels of volatility and reduced liquidity.

Large Shareholder Risk: To the extent a large proportion of the shares of the Fund are held by a small number of shareholders (or a single shareholder), including funds or accounts over which the Adviser has investment discretion, the Fund is subject to the risk that these shareholders will purchase or redeem Fund Shares in large amounts rapidly or unexpectedly, including as a result of an asset allocation decision made by the Adviser. These transactions could adversely affect the ability of the Fund to conduct its investment program.

Liquidity Risk: Lack of a ready market, stressed market conditions, or restrictions on resale may limit the ability of the Fund to sell a security at an advantageous time or price or at all. Illiquid investments may trade at a discount from comparable, more liquid investments and may be subject to wide fluctuations in market value. If the liquidity of the Fund's holdings deteriorates, it may lead to differences between the market price of Fund Shares and the net asset value of Fund Shares, and could result in the Fund Shares being less liquid. Illiquidity of the Fund's holdings may also limit the ability of the Fund to obtain cash to meet redemptions on a timely basis. In addition, the Fund, due to limitations on investments in any illiquid investments and/or the difficulty in purchasing and selling such investments, may be unable to achieve its desired level of exposure to a certain market or sector.

Mortgage-Related and Other Asset-Backed Securities Risk: Investments in mortgage-related and other asset-backed securities are subject to the risk of significant credit downgrades, illiquidity, and defaults to a greater extent than many other types of fixed-income investments. The liquidity of mortgage-related and asset-backed securities may change over time. During periods of falling interest rates, mortgage- and asset-backed securities may be called or prepaid, which may result in the Fund having to reinvest proceeds in other investments at a lower interest rate. During periods of rising interest rates, the average life of mortgage- and asset-backed securities may extend, which may lock in a below-market interest rate, increase the security's duration and interest rate sensitivity, and reduce the value of the security. Enforcing rights against the underlying assets or collateral may be difficult, and the underlying assets or collateral may be insufficient if the issuer defaults.

Municipal Obligations Risk: Issuers, including governmental issuers, may be unable to pay their obligations as they come due. The values of municipal obligations may be adversely affected by local political and economic conditions and developments. In addition, the values of municipal obligations that depend on a specific revenue source to fund their payment obligations may fluctuate as a result of actual or anticipated changes in the cash flows generated by the revenue source or changes in the priority of the municipal obligation to receive the cash flows generated by the revenue source. Municipal obligations may be more susceptible to downgrades or defaults during recessions or similar periods of economic stress. The secondary market for municipal obligations also tends to be less well-developed and less liquid than many other securities markets, which may limit the Fund's ability to sell its municipal obligations at attractive prices, particularly in stressed market conditions. The differences between the price at which an obligation can be purchased and the price at which it can be sold may widen during periods of market distress. Less liquid obligations can become more difficult to value and be subject to erratic price movements. In addition, changes in U.S. federal tax laws or the activity of an issuer may adversely affect the tax-exempt status of municipal obligations. Loss of tax-exempt status may result in a significant decline in the values of such municipal obligations.

Non-U.S. Securities Risk: Non-U.S. securities (including depositary receipts) are subject to political, regulatory, and economic risks not present in domestic investments. There may be less information publicly available about a non-U.S. entity than about a U.S. entity, and many non-U.S. entities are not subject to accounting, auditing, legal and financial report standards comparable to those in the United States. Further, such entities and/or their securities may be subject to risks associated with currency controls; expropriation; changes in tax policy; greater market volatility; differing securities market structures; higher transaction costs; and various administrative difficulties, such as delays in clearing and settling portfolio transactions or in receiving payment of dividends. Securities traded on foreign markets may be less liquid (harder to sell) than securities traded domestically. Foreign governments may impose restrictions on the repatriation of capital to the U.S. In addition, to the extent investments are made in a limited number of countries, events in those countries will have a more significant impact on the Fund. Investments in depositary receipts may be less liquid and more volatile than the underlying shares in their primary trading market.

Portfolio Turnover Risk: Frequent purchases and sales of portfolio securities may result in higher Fund expenses.

Risk of Investment in Other Pools: If the Fund invests in another pooled investment vehicle (e.g., a mutual fund or exchange-traded fund), it is exposed to the risk that the other pool will not perform as expected and is exposed indirectly to all of the risks applicable to an investment in such other pool. The investment policies of the other pool may not be the same as those of the Fund; as a result, an investment in the other pool may be subject to additional or different risks than those to which the Fund is typically subject. The Fund bears its proportionate share of the fees and expenses of any pool in which it invests. The Adviser or an affiliate may serve as investment adviser to a pool in which the Fund may invest, leading to potential conflicts of interest. It is possible that other clients of the Adviser or its affiliates will purchase or sell interests in a pool sponsored or managed by the Adviser or its affiliates at prices and at times more favorable than those at which the Fund does so.

U.S. Government Securities Risk: Certain U.S. government securities are supported by the full faith and credit of the United States; others are supported by the right of the issuer to borrow from the U.S. Treasury; others are supported by the discretionary authority of the U.S. government to purchase the agency's obligations; and still others are supported only by the credit of the issuing agency, instrumentality, or enterprise. Although U.S. government-sponsored enterprises such as the Federal Home Loan Mortgage Corporation (“Freddie Mac”) and the Federal National Mortgage Association (“Fannie Mae”) may be chartered or sponsored by Congress, they are not funded by Congressional appropriations, and their securities are not issued by the U.S. Treasury, are not supported by the full faith and credit of the U.S. government, and involve increased credit risks.

Valuation Risk: Some portfolio holdings, potentially a large portion of the Fund's investment portfolio, may be valued on the basis of factors other than market quotations. This may occur more often in times of market turmoil or reduced liquidity. There are multiple methods that can be used to value a portfolio holding when market quotations are not readily available. The value established for any portfolio holding at a point in time might differ from what would be produced using a different methodology or if it had been priced using market quotations. Portfolio holdings that are valued using techniques other than market quotations, including “fair valued” securities, may be subject to greater fluctuation in their valuations from one day to the next than if market quotations were used. In addition, there is no assurance that the Fund could sell or close out a portfolio position for the value established for it at any time, and it is possible that the Fund would incur a loss because a portfolio position is sold or closed out at a discount to the valuation established by the Fund at that time. Investors who purchase or redeem Fund Shares on days when the Fund is holding fair-valued investments may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the Fund had not fair-valued the holding(s) or had used a different valuation methodology.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by illustrating the variability of the Fund's returns from year-to-year and by showing how the Fund's average annual returns for the periods indicated compared with those of a broad-based benchmark index. The bar chart shows how the Fund's returns have varied for each full calendar year shown. Returns shown for periods prior to May 24, 2021 reflect the past performance of the General Electric RSP Income Fund, the performance predecessor of the Fund. The General Electric RSP Income Fund was managed by using investment policies, objectives, guidelines and restrictions that were substantially similar to those of the Fund. GE Asset Management Incorporated (“GEAM”) served as the Fund's investment adviser until 2016, when State Street Corporation (“State Street”), the ultimate parent company of the Adviser, acquired substantially all of the assets of GEAM. The Fund's past performance does not necessarily indicate how the Fund will perform in the future. Current performance information for the Fund is available toll free by calling (800) 242-0134 or by visiting our website at www.ssga.com.

Annual Total Returns (years ended 12/31)

Highest Quarterly Return: 7.74% (Q4, 2023)
Lowest Quarterly Return: -6.26% (Q1, 2022)

Average Annual Total Returns (for periods ended 12/31/23)

After tax returns have been omitted because all shareholders who purchase shares under this Prospectus hold Fund shares through tax-deferred arrangements.

	One Year	Five Years	Ten Years	Inception Date
State Street Income Fund				01/03/1980
Return Before Taxes	5.88 %	1.43 %	1.99 %
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)	5.53 %	1.10 %	1.81 %

Investment Adviser

SSGA FM serves as the investment adviser to the Fund.

The professionals primarily responsible for the day-to-day management of the Fund are Matthew Nest and James Palmieri. Mr. Nest and Mr. Palmieri have served as portfolio managers of the Fund since 2018 and 2019, respectively.

Matthew Nest, CFA, is a Managing Director of the Adviser and the Global Head of Active Fixed Income. He joined the Adviser in 2016.

James Palmieri, CFA, is a Managing Director of the Adviser, a Senior Portfolio Manager, and Head of Structured Credit for the Fundamental Active Fixed Income Team. He joined the Adviser in 2016 through the acquisition of GEAM by the ultimate parent company of State Street Global Advisors.

Purchase and Sale of Fund Shares

Purchase minimums

There are no minimum purchase amounts for initial or additional investments.

You may purchase or redeem Fund Shares on any day the Fund is open for business.

For General Electric Retirement Savings Plan Participants:

•

Visit benefits.ge.com and click on My GE RSP.

•

Call the GE RSP Service Center at 1-877-55-GERSP (1-877-554-3777) between 8:30 a.m. and 8:30 p.m., Eastern time, on any day the New York Stock Exchange is open for trading.

For the Plan:

•

You may redeem Fund Shares by written request or wire transfer.

•

Written requests should be sent to:

By Mail:

State Street Global Advisors
c/o U.S. Bank Global Fund Services
P.O. Box 701
Milwaukee, WI 53201-0701

By Overnight:

State Street Global Advisors
c/o U.S. Bank Global Fund Services
615 East Michigan Street
Milwaukee, WI 53202-5207

•

Calling us at (800) 242-0134; or

•

By accessing the Fund's website at www.ssga.com.

Tax Information

Since you are investing through a tax-advantaged 401(k) plan, dividends and capital gains distributions you receive from the Fund are not subject to federal income tax at the time of their distribution, but may be subject to federal income tax upon withdrawal.

State Street U.S. Core Equity Fund

Investment Objectives

The investment objective of the State Street U.S. Core Equity Fund (the “Fund”) is to seek long-term growth of capital.

Fees and Expenses of the Fund

Shareholder Fees (fees paid directly from your investment)

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	None
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the sale proceeds or the original offering price)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management Fee	0.12%
Distribution and/or Shareholder Service (12b-1) Fees	None
Other Expenses	0.02%
Total Annual Fund Operating Expenses	0.14%

Example:

1 year	3 years	5 years	10 years
$14	$45	$79	$179

Portfolio Turnover:

Principal Investment Strategies

Under normal circumstances, the Fund seeks to achieve its investment objective by investing at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of U.S. companies, such as common and preferred stocks. The Fund considers a company to be a U.S. company if it generates at least 50% of its revenues or profits from business activities in the U.S., has at least 50% of its assets situated in the U.S., or has the principal trading market for its securities in the U.S. At times, the Fund's investments may be focused in one or more market sectors, such as technology. The Fund will provide shareholders with at least sixty (60) days' notice prior to any change in its 80% investment policy.

Through fundamental company research involving analyzing financial statements and other information about a company, the portfolio managers primarily seek to identify securities of large and medium sized companies (meaning companies with market capitalizations of $2 billion or more) that they believe have desirable characteristics for the Fund such as:

•

low valuations in relation to their peers, the market, their historical valuations or their growth rate potential;

•

appropriate capital structures (i.e., in the opinion of SSGA Funds Management, Inc. (the “Adviser” or “SSGA FM”), appropriate levels of debt and financial leverage under the circumstances); and/or

•

high quality management focused on generating shareholder value.

The Fund also may invest up to 15% of its net assets (plus any borrowings for investment purposes) in foreign securities and up to 20% of its net assets (plus any borrowings for investment purposes) in debt securities. The portfolio managers may also use various types of derivative instruments (such as futures, options and forward contracts) to gain or hedge exposure to certain types of securities as an alternative to investing directly in or selling such securities. The Fund may short sell securities. The Fund may also invest in real estate investment trusts (“REITs”), and other registered investment companies, including exchange-traded funds (“ETFs”).

Principal Risks

Large-Capitalization Securities Risk: Returns on investments in securities of large companies could trail the returns on investments in securities of smaller and mid-sized companies. Larger companies may be unable to respond as quickly as smaller and mid-sized companies to competitive challenges or to changes in business, product, financial,

or other market conditions. Larger companies may not be able to maintain growth at the high rates that may be achieved by well-managed smaller and mid-sized companies.

Mid-Capitalization Securities Risk: The securities of mid-capitalization companies may be more volatile and may involve more risk than the securities of larger companies. These companies may have limited product lines, markets or financial resources, may lack the competitive strength of larger companies, and may depend on a few key employees. In addition, these companies may have been recently organized and may have little or no track record of success. The securities of mid-sized companies may trade less frequently and in smaller volumes than more widely held securities. Some securities of mid-sized issuers may be illiquid or may be restricted as to resale, and their values may be volatile.

REIT Risk: REITs are subject to the risks associated with investing in the securities of real property companies. In particular, REITs may be affected by changes in the values of the underlying properties that they own or operate. Further, REITs are dependent upon specialized management skills, and their investments may be concentrated in relatively few properties, or in a small geographic area or a single property type. REITs are also subject to heavy cash flow dependency and, as a result, are particularly reliant on the proper functioning of capital markets. A variety of economic and other factors may adversely affect a lessee's ability to meet its obligations to a REIT. In the event of a default by a lessee, the REIT may experience delays in enforcing its rights as a lessor and may incur substantial costs associated in protecting its investments. In addition, a REIT could fail to qualify for favorable regulatory treatment.

Debt Securities Risk: The values of debt securities may increase or decrease as a result of the following: market fluctuations, changes in interest rates, actual or perceived inability or unwillingness of issuers, guarantors or liquidity providers to make scheduled principal or interest payments, or illiquidity in debt securities markets. To the extent that interest rates rise, certain underlying obligations may be paid off substantially slower than originally anticipated and the value of those securities may fall sharply. A rising interest rate environment may cause the value of the Fund's fixed income securities to decrease, an adverse impact on the liquidity of the Fund's fixed income securities, and increased volatility of the fixed income markets. During periods when interest rates are at low levels, the Fund's yield can be low, and the Fund may have a negative yield (i.e., it may lose money on an operating basis). To the extent that interest rates fall, certain underlying obligations may be paid off substantially faster than originally anticipated. If the principal on a debt obligation is prepaid before expected, the prepayments of principal may have to be reinvested in obligations paying interest at lower rates. During periods of falling interest rates, the income received by the Fund may decline. Changes in interest rates will likely have a greater effect on the values of debt securities of longer durations. Returns on investments in debt securities could trail the returns on other investment options, including investments in equity securities. The U.S. Federal Reserve has been engaged in an aggressive campaign to raise interest rates in an effort to combat historically high levels of inflation. Interest rate increases may continue. High levels of inflation and/or a significantly changing interest rate environment can lead to heightened levels of volatility and reduced liquidity. See also “Extension Risk” and “Credit Risk” in the section titled “Additional Information about Investment Objectives, Principal Strategies, and Risks - Additional Information About Risks.”

Exchange-Traded Funds Risk: The Fund is subject to substantially the same risks as those associated with the direct ownership of the securities represented by an underlying ETF in which it invests.Also, the Fund bears its proportionate share of the fees and expenses of an underlying ETF in which it invests. In addition, the shares of an underlying ETF may trade at a premium or discount to their intrinsic value (i.e., the market value may differ from the net asset value of an ETF's shares) for a number of reasons. For example, supply and demand for shares of an underlying ETF or market disruptions may cause the market price of the underlying ETF to deviate from the value of the underlying ETF's investments, which may be exacerbated in less liquid markets.

Growth Stock Risk: The prices of growth stocks may be based largely on expectations of future earnings, and their prices can decline rapidly and significantly in reaction to negative news. Growth stocks may underperform value stocks and stocks in other broad style categories (and the stock market as a whole) over any period of time and may shift in and out of favor with investors generally, sometimes rapidly, depending on changes in market, economic, and other factors.

Short Sale Risk: Short sales are transactions in which the Fund sells a security it does not own. To complete the transaction, the Fund must borrow the security to make delivery to the buyer. The Fund is then obligated to replace the security borrowed by purchasing the security at the market price at the time of replacement. The price at such time may be higher or lower than the price at which the security was sold by the Fund. If the underlying security goes down in price between the time the Fund sells the security and buys it back, the Fund will realize a gain on the transaction. Conversely, if the underlying security goes up in price during the period, the Fund will realize a loss on the transaction. Any such loss is increased by the amount of premium or interest the Fund must pay to the lender of the security. Likewise, any gain will be decreased by the amount of premium or interest the Fund must pay to the lender of the security.

Information Technology Sector Risk: Market or economic factors impacting information technology companies could have a major effect on the value of the Fund's investments. The value of stocks of information technology companies is particularly vulnerable to rapid changes in technology product cycles, rapid product obsolescence, government regulation and competition, both domestically and internationally, including competition from foreign competitors with lower production costs. Like other technology companies, information technology companies may

have limited product lines, markets, financial resources or personnel. Stocks of technology companies and companies that rely heavily on technology, especially those of smaller, less-seasoned companies, tend to be more volatile than the overall market. Information technology companies are heavily dependent on patent and intellectual property rights, the loss or impairment of which may adversely affect profitability. Additionally, companies in the information technology sector may face dramatic and often unpredictable changes in growth rates and competition for the services of qualified personnel.

Value Stock Risk: A “value” style of investing is subject to the risk that the returns on “value” equity securities are less than returns on other styles of investing or the overall stock market. Value stocks present the risk that they may decline in price or never reach their expected full market value, either because the market fails to recognize a stock's intrinsic worth or the Adviser overestimates the stock's expected value.

Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by illustrating the variability of the Fund's returns from year-to-year and by showing how the Fund's average annual returns for the periods indicated compared with those of a broad-based benchmark index. The bar chart shows how the Fund's returns have varied for each full calendar year shown. Returns shown for periods prior to May 24, 2021 reflect the past performance of the General Electric RSP U.S. Equity Fund, the performance predecessor of the Fund. The General Electric RSP U.S. Equity Fund was managed by using investment policies, objectives, guidelines and restrictions that were substantially similar to those of the Fund. GE Asset Management Incorporated (“GEAM”) served as the Fund's investment adviser until 2016, when State Street Corporation (“State Street”), the ultimate parent company of the Adviser, acquired substantially all of the assets of GEAM. The Fund's past performance does not necessarily indicate how the Fund will perform in the future. Current performance information for the Fund is available toll free by calling (800) 242-0134 or by visiting our website at www.ssga.com.

Annual Total Returns (years ended 12/31)

Highest Quarterly Return: 21.61% (Q2, 2020)
Lowest Quarterly Return: -17.71% (Q1, 2020)

Average Annual Total Returns (for periods ended 12/31/23)

After tax returns have been omitted because all shareholders who purchase shares under this Prospectus hold Fund shares through tax-deferred arrangements.

	One Year	Five Years	Ten Years	Inception Date
State Street US Core Equity Fund				01/01/1980
Return Before Taxes	28.85 %	16.86 %	12.02 %
S&P 500 Index (reflects no deduction for fees, expenses or taxes)	26.29 %	15.69 %	12.03 %

Investment Adviser

SSGA FM serves as the investment adviser to the Fund.

The professionals primarily responsible for the day-to-day management of the Fund are Michael Solecki, Paul Nestro and Chris Sierakowski. Mr. Solecki has served as a portfolio manager of the Fund since 2019, Mr. Nestro has served as a portfolio manager of the Fund since 2018 and Mr. Sierakowski has served as a portfolio manager of the Fund since 2017.

Michael Solecki, CFA, is a Senior Managing Director of the Adviser, Portfolio Manager and the Chief Investment Officer for Fundamental Equity. He joined the Adviser in 2016 through the acquisition of GEAM by the ultimate parent company of State Street Global Advisors.

Paul Nestro, CFA, is a Managing Director of the Adviser and the Director of Fundamental Growth and Core Equity Research. He joined the Adviser in 2016 through the acquisition of GEAM by the ultimate parent company of State Street Global Advisors.

Chris Sierakowski, CFA, is a Managing Director of the Adviser and a Portfolio Manager in the Fundamental Growth and Core U.S. Equity Group. He joined the Adviser in 2016 through the acquisition of GEAM by the ultimate parent company of State Street Global Advisors.

Purchase and Sale of Fund Shares

Purchase minimums

There are no minimum purchase amounts for initial or additional investments.

You may purchase or redeem Fund Shares on any day the Fund is open for business.

For General Electric Retirement Savings Plan Participants:

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Visit benefits.ge.com and click on My GE RSP.

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Call the GE RSP Service Center at 1-877-55-GERSP (1-877-554-3777) between 8:30 a.m. and 8:30 p.m., Eastern time, on any day the New York Stock Exchange is open for trading.

For the Plan:

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You may redeem Fund Shares by written request or wire transfer.

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Written requests should be sent to:

By Mail:

State Street Global Advisors
c/o U.S. Bank Global Fund Services
P.O. Box 701
Milwaukee, WI 53201-0701

By Overnight:

State Street Global Advisors
c/o U.S. Bank Global Fund Services
615 East Michigan Street
Milwaukee, WI 53202-5207

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Calling us at (800) 242-0134; or

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By accessing the Fund's website at www.ssga.com.

Tax Information

Additional Information About Investment Objectives, Principal Strategies and Risks

Investment Objectives

The State Street Institutional Investment Trust's (the “Trust”) Board of Trustees (the “Board”) may change each Fund's investment strategies and other policies without shareholder approval, except as otherwise indicated. The Board may change each Fund's investment objective without shareholder approval.

Principal Investment Strategies

State Street Income Fund

Under normal circumstances, the Fund seeks to achieve its investment objective by investing at least 80% of its net assets in debt securities.

The Fund invests significantly in a variety of investment-grade debt securities, such as agency mortgage-backed securities, asset-backed securities, corporate bonds, municipal obligations, government securities and money market instruments. Investment-grade securities include securities rated Baa3 or higher by Moody's or BBB- or higher by S&P (and securities of comparable quality as determined by the Adviser). The Fund normally has a weighted average effective maturity of approximately five to ten years, but is subject to no limitation with respect to the maturities of the instruments in which it may invest.

U.S. Government securities are securities that are issued or guaranteed as to principal or interest by the U.S. Government or one of its agencies or instrumentalities. Some U.S. Government securities are backed by the full faith and credit of the U.S. Government, such as U.S. Treasury bills and notes and obligations of Government National Mortgage Association (“Ginnie Mae”). Other U.S. Government securities are neither issued by nor guaranteed by the full faith and credit of the U.S. Government, including those issued by Federal National Mortgage Association (“Fannie Mae”) and Federal Home Loan Mortgage Corporation (“Freddie Mac”). Fannie Mae and Freddie Mac have been operating under a conservatorship since 2008, with the Federal Housing Finance Agency acting as their conservator, and receive certain financing support from and have access to certain borrowing arrangements with the U.S. Treasury.

The portfolio managers seek to identify debt securities that they believe have desirable characteristics for the Fund such as:

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attractive yields and prices;

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the potential for capital appreciation; and/or

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reasonable credit quality.

The Fund may engage in active and frequent trading of its portfolio securities.

State Street U.S. Core Equity Fund

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low valuations in relation to their peers, the market, their historical valuations or their growth rate potential;

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appropriate capital structures (i.e., in the opinion of the Adviser, appropriate levels of debt and financial leverage under the circumstances); and/or

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high quality management focused on generating shareholder value.

Additional Information About Risks

The Funds are subject to the following risks. The risks are described in alphabetical order and not in the order of importance or potential exposure. Each principal risk without a parenthetical indicating a single Fund's name is applicable to both Funds.

Below Investment-Grade Securities Risk (principal risk for State Street Income Fund). Securities rated below investment-grade and unrated securities of comparable credit quality (commonly known as “high-yield” or “junk” bonds) lack strong investment-grade characteristics, are considered predominantly speculative with respect to the issuer's continuing ability to make principal and interest payments, and are subject to greater levels of credit, liquidity and market risk than higher-rated securities. They can involve a substantially greater risk of default than higher-rated securities, and their values can decline significantly over short periods of time. Issuers of lower-quality debt securities may have substantially greater risk of insolvency or bankruptcy than issuers of higher-quality debt securities. In the event the issuer of a debt security held by a Fund defaults on its payments or becomes insolvent or bankrupt, the Fund may not receive the return it was promised on the investment and could lose its entire investment. The lower ratings of junk bonds reflect a greater possibility that actual or perceived adverse changes in the financial condition of the issuer or in general economic conditions, or an unanticipated rise in interest rates, may impair the ability of the issuer to make payments of interest and principal. If this were to occur, the values of such securities held by a Fund may fall substantially and the Fund could lose some or all of the value of its investment. Lower-quality debt securities tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt securities. The market for lower quality debt securities can be less liquid than for higher quality debt securities, especially during periods of recession or general market decline, which could make it difficult at times for a Fund to sell certain securities at prices used in calculating the Fund's net asset value. These securities may have significant volatility.

Call/Prepayment Risk. Call/prepayment risk is the risk that an issuer will exercise its right to pay principal on an obligation held by a Fund earlier than expected or required. This may occur, for example, when there is a decline in interest rates, and an issuer of bonds or preferred stock redeems the bonds or stock in order to replace them with obligations on

which it is required to pay a lower interest or dividend rate. It may also occur when there is an unanticipated increase in the rate at which mortgages or other receivables underlying mortgage- or asset-backed securities held by a Fund are prepaid. In any such case, a Fund may be forced to invest the prepaid amounts in lower-yielding investments, resulting in a decline in the Fund's income.

Company Risk. Changes in the financial condition of a company or other issuer, changes in specific market, economic, political, regulatory, geopolitical, and other conditions that affect a particular type of investment or issuer, and changes in general market, economic, political, regulatory, geopolitical and other conditions can adversely affect the price of an investment. The price of securities of smaller, less well-known issuers can be more volatile than the price of securities of larger issuers or the market in general.

Counterparty Risk. A Fund will be subject to credit risk with respect to the counterparties with which the Fund enters into derivatives contracts and other transactions such as repurchase agreements or reverse repurchase agreements. A Fund's ability to profit from these types of investments and transactions will depend on the willingness and ability of its counterparty to perform its obligations. If a counterparty fails to meet its contractual obligations, a Fund may be unable to terminate or realize any gain on the investment or transaction, resulting in a loss to the Fund. A Fund may experience significant delays in obtaining any recovery in an insolvency, bankruptcy, or other reorganization proceeding involving its counterparty (including recovery of any collateral posted by it) and may obtain only a limited recovery or may obtain no recovery in such circumstances. If a Fund holds collateral posted by its counterparty, it may be delayed or prevented from realizing on the collateral in the event of a bankruptcy or insolvency proceeding relating to the counterparty. Under applicable law or contractual provisions, including if a Fund enters into an investment or transaction with a financial institution and such financial institution (or an affiliate of the financial institution) experiences financial difficulties, then the Fund may in certain situations be prevented or delayed from exercising its rights to terminate the investment or transaction, or to realize on any collateral and may result in the suspension of payment and delivery obligations of the parties under such investment or transactions or in another institution being substituted for that financial institution without the consent of the Fund. Further, a Fund may be subject to “bail-in” risk under applicable law whereby, if required by the financial institution's authority, the financial institution's liabilities could be written down, eliminated or converted into equity or an alternative instrument of ownership. A bail-in of a financial institution may result in a reduction in value of some or all of its securities and, if a Fund holds such securities or has entered into a transaction with such a financial security when a bail-in occurs, such Fund may also be similarly impacted.

Credit Risk. Credit risk is the risk that an issuer, guarantor or liquidity provider of a fixed-income security held by a Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise honor its obligations. It includes the risk that the security will be downgraded by a credit rating agency; generally, lower credit quality issuers present higher credit risks. An actual or perceived decline in creditworthiness of an issuer of a fixed-income security held by a Fund may result in a decrease in the value of the security. It is possible that the ability of an issuer to meet its obligations will decline substantially during the period when a Fund owns securities of the issuer or that the issuer will default on its obligations or that the obligations of the issuer will be limited or restructured.

The credit rating assigned to any particular investment does not necessarily reflect the issuer's current financial condition and does not reflect an assessment of an investment's volatility or liquidity. Securities rated in the lowest category of investment-grade are considered to have speculative characteristics. If a security held by a Fund loses its rating or its rating is downgraded, the Fund may nonetheless continue to hold the security in the discretion of the Adviser. In the case of asset-backed or mortgage-related securities, changes in the actual or perceived ability of the obligors on the underlying assets or mortgages to make payments of interest and/or principal may affect the values of those securities.

Currency Risk. Investments in issuers in different countries are often denominated in currencies other than the U.S. dollar. Changes in the values of those currencies relative to the U.S. dollar may have a positive or negative effect on the values of a Fund's investments denominated in those currencies. The values of other currencies relative to the U.S. dollar may fluctuate in response to, among other factors, interest rate changes, intervention (or failure to intervene) by national governments, central banks, or supranational entities such as the International Monetary Fund, the imposition of currency controls, and other political or regulatory developments. Currency values can decrease significantly both in the short term and over the long term in response to these and other developments. Continuing uncertainty as to the status

of the Euro and the Economic and Monetary Union of the European Union (the “EMU”) has created significant volatility in currency and financial markets generally. Any partial or complete dissolution of the EMU, or any continued uncertainty as to its status, could have significant adverse effects on currency and financial markets, and on the values of a Fund's portfolio investments.

Debt Securities Risk. The values of debt securities may increase or decrease as a result of the following: market fluctuations, changes in interest rates, actual or perceived inability or unwillingness of issuers, guarantors or liquidity providers to make scheduled principal or interest payments or illiquidity in debt securities markets. To the extent that interest rates rise, certain underlying obligations may be paid off substantially slower than originally anticipated and the value of those securities may fall sharply. A rising interest rate environment may cause the value of a Fund's fixed income securities to decrease, an adverse impact on the liquidity of a Fund's fixed income securities, and increased volatility of the fixed income markets. During periods when interest rates are at low levels, a Fund's yield can be low, and a Fund may have a negative yield (i.e., it may lose money on an operating basis). To the extent that interest rates fall, certain underlying obligations may be paid off substantially faster than originally anticipated. If the principal on a debt obligation is prepaid before expected, the prepayments of principal may have to be reinvested in obligations paying interest at lower rates. During periods of falling interest rates, the income received by a Fund may decline. Changes in interest rates will likely have a greater effect on the values of debt securities of longer durations. Returns on investments in debt securities could trail the returns on other investment options, including investments in equity securities. The U.S. Federal Reserve has been engaged in an aggressive campaign to raise interest rates in an effort to combat high levels of inflation. Interest rate increases may continue. High levels of inflation and/or a significantly changing interest rate environment can lead to heightened levels of volatility and reduced liquidity.

Derivatives Risk. A derivative is a financial contract the value of which depends on, or is derived from, the value of an underlying asset, interest rate, or index. Derivative transactions typically involve leverage and may have significant volatility. It is possible that a derivative transaction will result in a loss greater than the principal amount invested, that changes in the value of a derivative transaction may not correlate perfectly with the underlying asset, and that a Fund may not be able to close out a derivative transaction at a favorable time or price. Risks associated with derivative instruments include potential changes in value in response to interest rate changes or other market developments or as a result of the counterparty's credit quality; the potential for the derivative transaction not to have the effect the Adviser anticipated or a different or less favorable effect than the Adviser anticipated; the failure of the counterparty to the derivative transaction to perform its obligations under the transaction or to settle a trade; possible mispricing or improper valuation of the derivative instrument; imperfect correlation in the value of a derivative with the asset, rate, or index underlying the derivative; the risk that a Fund may be required to post collateral or margin with its counterparty, and will not be able to recover the collateral or margin in the event of the counterparty's insolvency or bankruptcy; the risk that a Fund will experience losses on its derivatives investments and on its other portfolio investments, even when the derivatives investments may be intended in part or entirely to hedge those portfolio investments; the risks specific to the asset underlying the derivative instrument; lack of liquidity for the derivative instrument, including, without limitation, absence of a secondary trading market; the potential for reduced returns to a Fund due to losses on the transaction and an increase in volatility; the potential for the derivative transaction to have the effect of accelerating the recognition of gain; and legal risks arising from the documentation relating to the derivative transaction.

Forward Currency Contracts Risk. In a forward currency contract, a Fund agrees to buy in the future an amount in one currency in return for another currency, at an exchange rate determined at the time the contract is entered into. If currency exchange rates move against a Fund's position during the term of the contract, the Fund will lose money on the contract. There is no limit on the extent to which exchange rates may move against a Fund's position. The markets for certain currencies may at times become illiquid, and a Fund may be unable to enter into new forward contracts or to close out existing contracts. Forward currency contracts are entered into in the over-the-counter market, and a Fund's ability to profit from a contract will depend on the willingness and ability of its counterparty to perform its obligations under the contract. Use by a Fund of foreign currency forward contracts may give rise to investment leverage.

Futures Contract Risk. The risk of loss relating to the use of futures contracts is potentially unlimited. The ability to establish and close out positions in futures contracts will be subject to the development and maintenance of a liquid secondary market. There is no assurance that a liquid secondary market on an exchange will exist for any particular futures contract or at any particular time. In the event no such market exists, it might not be possible to effect closing transactions, and a Fund will be unable to terminate the futures contract. In using futures contracts, a Fund will be reliant on the ability of the Adviser to predict market and price movements correctly; the skills needed to use

such futures contracts successfully are different from those needed for traditional portfolio management. If a Fund uses futures contracts for hedging purposes, there is a risk of imperfect correlation between movements in the prices of the futures contracts and movements in the securities or index underlying the futures contracts or movements in the prices of the Fund's investments that are the subject of such hedge. The prices of futures contracts, for a number of reasons, may not correlate perfectly with movements in the securities or index underlying them. For example, participants in the futures markets are subject to margin deposit requirements. Such requirements may cause investors to take actions with respect to their futures positions that they would not otherwise take. The margin requirements in the futures markets may be less onerous than margin requirements in the securities markets in general, and as a result those markets may attract more speculators than the securities markets do. Increased participation by speculators in those markets may cause temporary price distortions. Due to the possibility of price distortion, even a correct forecast of general market trends by the Adviser still may not result in a successful futures activity over a very short time period. The risk of a position in a futures contract may be very large compared to the relatively low level of margin a Fund is required to deposit. A Fund will typically be required to post margin with its futures commission merchant in connection with its transactions in futures contracts. In many cases, a relatively small price movement in a futures contract may result in immediate and substantial loss or gain to the investor relative to the size of a required margin deposit. A Fund will incur brokerage fees in connection with its futures transactions. In the event of an insolvency of the futures commission merchant or a clearing house, a Fund may not be able to recover all (or any) of the margin it has posted with the futures commission merchant, or to realize the value of any increase in the price of its positions, or it may experience a significant delay in doing so. The Commodity Futures Trading Commission (the “CFTC”) and the various exchanges have established limits referred to as “speculative position limits” on the maximum net long or net short positions that any person and certain affiliated entities may hold or control in a particular futures contract. In addition, federal position limits apply to swaps that are economically equivalent to futures contracts that are subject to CFTC-set speculative limits. All positions owned or controlled by the same person or entity, even if in different accounts, must be aggregated for purposes of complying with position limits. It is possible that the positions of different clients managed by the Adviser may be aggregated for this purpose. Therefore, the trading decisions of the Adviser may have to be modified and positions held by a Fund liquidated in order to avoid exceeding such limits. The modification of investment decisions or the elimination of open positions, if it occurs, may adversely affect the performance of a Fund. A violation of position limits could also lead to regulatory action materially adverse to a Fund's investment strategy. In addition, exchanges may establish accountability levels applicable to a futures contract instead of position limits, provided that the futures contract is not subject to federal position limits. An exchange may order a person who holds or controls a position in excess of a position accountability level not to further increase its position, to comply with any prospective limit that exceeds the size of the position owned or controlled, or to reduce any open position that exceeds the position accountability level if the exchange determines that such action is necessary to maintain an orderly market. Position accountability levels could adversely affect a Fund's ability to establish and maintain positions in commodity futures contracts to which such levels apply, if the Fund were to trade in such contracts, and a Fund's ability to achieve its investment objective.

Futures contracts traded on markets outside the U.S. are not generally subject to the same level of regulation by the CFTC or other U.S. regulatory entities as contracts traded in the U.S., including without limitation as to the execution, delivery, and clearing of transactions. U.S. regulators neither regulate the activities of a foreign exchange, nor have the power to compel enforcement of the rules of the foreign exchange or the laws of the foreign country in question. Margin and other payments made by the Fund may not be afforded the same protections as are afforded those payments in the U.S., including in connection with the insolvency of an executing or clearing broker or a clearinghouse or exchange. Certain foreign futures contracts may be less liquid and more volatile than U.S. contracts.

Swaps Risk. A swap is a two-party contract that generally obligates the parties to exchange payments based on a specified reference security, basket of securities, security index or index component. Swaps can involve greater risks than direct investment in securities because swaps may be leveraged and are subject to counterparty risk (e.g., the risk of a counterparty's defaulting on the obligation or bankruptcy), credit risk and pricing risk (i.e., swaps may be difficult to value). Swaps may also be considered illiquid. It may not be possible for a Fund to liquidate a swap position at an advantageous time or price, which may result in significant losses.

Options Risk. The Funds' successful use of options depends on the ability of the Adviser to forecast market movements correctly. For example, if a Fund were to write a call option on a security based on the Adviser's expectation that the price of the security would fall, but the price were to rise instead, the Fund could be required to sell the security upon exercise at a price below the current market price. Similarly, if a Fund were to write a put option based on the Adviser's expectation that the price of the underlying security would rise, but the price were to fall instead, the

Fund could be required to purchase the security upon exercise at a price higher than the current market price. When a Fund purchases an option, it runs the risk that it will lose its entire investment in the option in a relatively short period of time, unless the Fund exercises the option or enters into a closing sale transaction before the option's expiration. If the price of the underlying security does not rise (in the case of a call) or fall (in the case of a put) to an extent sufficient to cover the option premium and transaction costs, a Fund will lose part or all of its investment in the option. This contrasts with an investment by a Fund in the underlying security, since the Fund will not realize a loss if the security's price does not change over a relatively short time period. The effective use of options also depends on a Fund's ability to terminate option positions at times when the Adviser deems it desirable to do so. There is no assurance that a Fund will be able to effect closing transactions at any particular time or at an acceptable price. The sale of options by a Fund may create investment leverage.

Emerging Markets Risk (principal risk for State Street Income Fund). Investments in emerging markets are generally subject to a greater risk of loss than investments in developed markets. This may be due to, among other things, the possibility of greater market volatility, lower trading volume and liquidity, greater risk of expropriation, nationalization, and social, political and economic instability, greater reliance on a few industries, international trade or revenue from particular commodities, less developed accounting, legal and regulatory systems, higher levels of inflation, deflation or currency devaluation, greater risk of market shutdown, and more significant governmental limitations on investment policy as compared to those typically found in a developed market. The Public Company Accounting Oversight Board, which regulates auditors of U.S. public companies, is unable to inspect audit work papers in certain foreign countries. Investors in foreign countries often have limited rights and few practical remedies to pursue shareholder claims, including class actions or fraud claims, and the ability of the U.S. Securities and Exchange Commission (“SEC”), the U.S. Department of Justice and other authorities to bring and enforce actions against foreign issuers or foreign persons is limited. In addition, issuers (including governments) in emerging market countries may have less financial stability than in other countries. The securities of emerging market companies may trade less frequently and in smaller volumes than more widely held securities. Market disruptions or substantial market corrections may limit very significantly the liquidity of securities of certain companies in a particular country or geographic region, or of all companies in the country or region. A Fund may be unable to liquidate its positions in such securities at any time, or at a favorable price, in order to meet the Fund's obligations. There is also the potential for unfavorable action such as embargo and acts of war. As a result, there will tend to be an increased risk of price volatility in investments in emerging market countries, which may be magnified by currency fluctuations relative to the U.S. dollar. Settlement and asset custody practices for transactions in emerging markets may differ from those in developed markets. Such differences may include possible delays in settlement and certain settlement practices, such as delivery of securities prior to receipt of payment, which increase the likelihood of a “failed settlement.” Failed settlements can result in losses. For these and other reasons, investments in emerging markets are often considered speculative.

Equity Investing Risk. The market prices of equity securities owned by a Fund may go up or down, sometimes rapidly or unpredictably. The value of a security may decline for a number of reasons that may directly relate to the issuer, such as management performance, financial leverage, non-compliance with regulatory requirements, and reduced demand for the issuer's goods or services. The values of equity securities also may decline due to general industry or market conditions that are not specifically related to a particular company, such as real or perceived adverse economic conditions, changes in the general outlook for corporate earnings, changes in interest or currency rates, or adverse investor sentiment generally. In addition, equity markets tend to move in cycles, which may cause stock prices to fall over short or extended periods of time.

Exchange Traded Products Risk (principal risk for State Street Income Fund). A Fund is subject to substantially the same risks as those associated with the direct ownership of the securities or other assets represented by the ETPs in which a Fund invests. The shares of certain ETPs may trade at a premium or discount to their net asset values. For example, supply and demand for shares of an underlying ETF or market disruptions may cause the market price of the underlying ETF to deviate from the value of the underlying ETF's investments, which may be exacerbated in less liquid markets. The value of an exchange traded note may also differ from the valuation of its reference market due to changes in the issuer's credit rating.

Affiliated ETP Risk. The Adviser may receive management or other fees from Affiliated ETPs, as well as a management fee for managing the Fund. It is possible that a conflict of interest among the Fund and the Affiliated ETPs could affect how the Adviser fulfills its fiduciary duties to the Fund and the Affiliated ETPs. Because the amount of the investment management fees to be retained by the Adviser may differ depending upon the Affiliated ETPs in which the Fund invests, there is a conflict of interest for the Adviser in selecting the Affiliated ETPs. In addition, the

Adviser may have an incentive to take into account the effect on an Affiliated ETP in which the Fund may invest in determining whether, and under what circumstances, to purchase or sell shares in that Affiliated ETP. Although the Adviser takes steps to address the conflicts of interest, it is possible that the conflicts could impact the Fund.

Extension Risk. During periods of rising interest rates, the average life of certain types of securities may be extended because of slower-than-expected principal payments. This may increase the period of time during which an investment earns a below-market interest rate, increase the security's duration and reduce the value of the security. Extension risk may be heightened during periods of adverse economic conditions generally, as payment rates decline due to higher unemployment levels and other factors.

Growth Stock Risk (principal risk for State Street U.S. Core Equity Fund). The prices of growth stocks may be based largely on expectations of future earnings, and their prices can decline rapidly and significantly in reaction to negative news about such factors as earnings, revenues, the economy, political developments, or other news. Growth stocks may underperform value stocks and stocks in other broad style categories (and the stock market as a whole) over any period of time and may shift in and out of favor with investors generally, sometimes rapidly, depending on changes in market, economic, and other factors. As a result, at times when it holds substantial investments in growth stocks, a Fund may underperform other investment funds that invest more broadly or that favor different investment styles. Because growth companies typically reinvest their earnings, growth stocks typically do not pay dividends at levels associated with other types of stocks, if at all.

Interest Rate Risk (principal risk for State Street Income Fund). Interest rate risk is the risk that the securities held by a Fund will decline in value because of increases in market interest rates. Duration is a measure used to determine the sensitivity of a security's price to changes in interest rates. Debt securities with longer durations tend to be more sensitive to changes in interest rates, usually making them more volatile than debt securities with shorter durations. For example, the value of a security with a duration of five years would be expected to decrease by 5% for every 1% increase in interest rates. Falling interest rates also create the potential for a decline in a Fund's income and yield. Interest-only and principal-only securities are especially sensitive to interest rate changes, which can affect not only their prices but can also change the income flows and repayment assumptions about those investments. Variable and floating rate securities also generally increase or decrease in value in response to changes in interest rates, although generally to a lesser degree than fixed-rate securities. A substantial increase in interest rates may also have an adverse impact on the liquidity of a security, especially those with longer durations. Changes in governmental policy, including changes in central bank monetary policy, could cause interest rates to rise rapidly, or cause investors to expect a rapid rise in interest rates. This could lead to heightened levels of interest rate, volatility and liquidity risks for the fixed income markets generally and could have a substantial and immediate effect on the values of a Fund's investments. The U.S. Federal Reserve has been in engaged in an aggressive campaign to raise interest rates in an effort to combat historically high levels of inflation. Interest rate increases may continue. High levels of inflation and/or a significantly changing interest rate environment can lead to heightened levels of volatility and reduced liquidity.

Large-Capitalization Securities Risk (principal risk for State Street U.S. Core Equity Fund). Securities issued by large-capitalization companies may present risks not present in smaller companies. For example, larger companies may be unable to respond as quickly as smaller and mid-sized companies to competitive challenges or to changes in business, product, financial, or other market conditions. Larger companies may not be able to maintain growth at the high rates that may be achieved by well-managed smaller and mid-sized companies, especially during strong economic periods. Returns on investments in securities of large companies could trail the returns on investments in securities of smaller and mid-sized companies.

Large Shareholder Risk. To the extent a large proportion of the shares of a Fund are highly concentrated or held by a small number of shareholders (or a single shareholder), including funds or accounts over which the Adviser has investment discretion, a Fund is subject to the risk that these shareholders will purchase or redeem Fund shares in large amounts rapidly or unexpectedly, including as a result of an asset allocation decision made by the Adviser. These transactions could adversely affect the ability of a Fund to conduct its investment program. For example, they could require a Fund to sell portfolio securities or purchase portfolio securities unexpectedly and incur substantial transaction costs or a Fund may be required to sell its more liquid portfolio investments to meet a large redemption, in which case a Fund's remaining assets may be less liquid, more volatile, and more difficult to price. A Fund may hold a relatively large proportion of its assets in cash in anticipation of large redemptions, diluting its investment returns.

Liquidity Risk (principal risk for State Street Income Fund). Liquidity risk is the risk that a Fund may not be able to dispose of investments readily at a favorable time or prices (or at all) or at prices approximating those at which a Fund currently values them. For example, certain investments may be subject to restrictions on resale, may trade in the over-the-counter market or in limited volume, or may not have an active trading market. Illiquid investments may trade at a discount from comparable, more liquid investments and may be subject to wide fluctuations in market value. It may be difficult for a Fund to value illiquid investments accurately. The market for certain investments may become illiquid under adverse market or economic conditions independent of any specific adverse changes in the conditions of a particular issuer. If the liquidity of a Fund's holdings deteriorates, it may lead to differences between the market price of Fund Shares and the net asset value of Fund Shares, and could result in the Fund Shares being less liquid. Disposal of illiquid investments may entail registration expenses and other transaction costs that are higher than those for liquid investments. A Fund may seek to borrow money to meet its obligations (including among other things redemption obligations) if it is unable to dispose of illiquid investments, resulting in borrowing expenses and possible leveraging of the Fund. In some cases, due to unanticipated levels of illiquidity the Fund may choose to meet its redemption obligations wholly or in part by distributions of assets in-kind.

The term “illiquid investments” for this purpose means securities that a Fund 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 securities. If any Fund determines at any time that it owns illiquid investments in excess of 15% of its net assets, it will cease to undertake new commitments to acquire illiquid investments until its holdings are no longer in excess of 15% of its net asset value (“NAV”), report the occurrence in compliance with Rule 30b1-10 under the Investment Company Act of 1940, as amended (the “1940 Act”) and, depending on circumstances, may take additional steps to reduce its holdings of illiquid investments.

The SEC has recently proposed rule amendments that, if adopted as proposed, could result in a larger percentage of the Fund's investments being classified as illiquid investments.

Management Risk. Each Fund is actively managed. The Adviser's judgments about the attractiveness, relative value, or potential appreciation of a particular sector, security, commodity or investment strategy may prove to be incorrect, and may cause a Fund to incur losses. There can be no assurance that the Adviser's investment techniques and decisions will produce the desired results.

Market Risk. Market prices of investments held by a Fund will go up or down, sometimes rapidly or unpredictably. A Fund's investments are subject to changes in general economic conditions, general market fluctuations and the risks inherent in investment in securities markets. Investment markets can be volatile, and prices of investments can change substantially due to various factors, including, but not limited to, economic growth or recession, changes in interest rates, inflation, changes in actual or perceived creditworthiness of issuers and general market liquidity. Even if general economic conditions do not change, the value of an investment in a Fund could decline if the particular industries, sectors or companies in which the Fund invests do not perform well or are adversely affected by events. Further, legal, political, regulatory and tax changes also may cause fluctuations in markets and securities prices. Local, regional or global events such as war, military conflicts, acts of terrorism, natural disasters, public health issues, or other events could have a significant impact on a Fund and its investments. Due to the interconnectedness of economies and financial markets throughout the world, if a Fund invests in securities of issuers located in or with significant exposure to countries experiencing economic and financial difficulties, the value and liquidity of the Fund's investments may be negatively affected. A widespread outbreak of an infectious illness, such as COVID-19, and efforts to contain its spread, may result in market volatility, inflation, reduced liquidity of certain instruments, disruption in the trading of certain instruments, and systemic economic weakness. The foregoing could impact a Fund and its investments and result in disruptions to the services provided to a Fund by its service providers.

Additionally, in March 2023, the shutdown of certain financial institutions raised economic concerns over disruption in the U.S. banking system. There can be no certainty that the actions taken by the U.S. government to strengthen public confidence in the U.S. banking system will be effective in mitigating the effects of financial institution failures on the economy and restoring public confidence in the U.S. banking system.

Market Disruption and Geopolitical Risk. A Fund is subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. War, terrorism, and related geopolitical events have led, and in the future may lead, to increased short-term market volatility and may have adverse long-term effects on U.S. and world economies and markets generally. Likewise, natural and environmental disasters, pandemics and epidemics, and sys

temic market dislocations may be highly disruptive to economies and markets. Those events, as well as other changes in foreign and domestic economic and political conditions, also could adversely affect individual issuers or related groups of issuers, securities markets, interest rates, credit ratings, inflation, investor sentiment, and other factors affecting the value of a Fund's investments. Given the increasing interdependence among global economies and markets, conditions in one country, market, or region might adversely affect markets, issuers, and/or foreign exchange rates in other countries, including the U.S. Any partial or complete dissolution of the EMU, or any increased uncertainty as to its status, could have significant adverse effects on currency and financial markets, and on the values of a Fund's investments. On January 31, 2020, the United Kingdom (“UK”) formally withdrew from the European Union (“EU”) (commonly known as “Brexit”). An agreement between the UK and the EU governing their future trade relationship became effective January 1, 2021, but critical aspects of the relationship remain unresolved and subject to further negotiation and agreement. There is still considerable uncertainty relating to the potential consequences associated with the exit, how the negotiations for new trade agreements will be conducted, and whether the U.K.'s exit will increase the likelihood of other countries also departing the EU. Brexit may have a significant impact on the U.K., Europe, and global economies, which may result in increased volatility and illiquidity, new legal, political, economic and regulatory uncertainties and potentially lower economic growth for these economies that could potentially have an adverse effect on the value of the Funds' investments. Any further exits from the EU, or the possibility of such exits, or the abandonment of the euro, may cause additional market disruption globally and introduce new legal and regulatory uncertainties.

Securities and financial markets may be susceptible to market manipulation or other fraudulent trade practices, which could disrupt the orderly functioning of these markets or adversely affect the values of investments traded in these markets, including investments held by a Fund. To the extent a Fund has focused its investments in the market or index of a particular region, adverse geopolitical and other events could have a disproportionate impact on the Fund.

Mid-Capitalization Securities Risk (principal risk for State Street U.S. Core Equity Fund). The securities of mid-capitalization companies may be more volatile and may involve more risk than the securities of larger companies. These companies may have limited product lines, markets or financial resources, may lack the competitive strength of larger companies, and may depend on a few key employees. In addition, these companies may have been recently organized and may have little or no track record of success. The securities of mid-sized companies may trade less frequently and in smaller volumes than more widely held securities. The prices of these securities may fluctuate more sharply than those of other securities, and a Fund may experience some difficulty in establishing or closing out positions in these securities at prevailing market prices. There may be less publicly available information about the issuers of these securities or less market interest in these securities than in the case of larger companies, both of which can cause significant price volatility. Some securities of mid-sized issuers may be illiquid or may be restricted as to resale. Returns on investments in securities of mid-capitalization companies could trail the returns on investments in securities of larger or smaller companies.

Mortgage-Related and Other Asset-Backed Securities Risk (principal risk for the State Street Income Fund). Investments in mortgage-related and other asset-backed securities are subject to the risk of significant credit downgrades, illiquidity, and defaults to a greater extent than many other types of fixed income investments. The liquidity of mortgage-related and asset-backed securities may change over time. Mortgage-related securities represent a participation in, or are secured by, mortgage loans. Other asset-backed securities are typically structured like mortgage-related securities, but instead of mortgage loans or interests in mortgage loans, the underlying assets may include, for example, items such as motor vehicle installment sales or installment loan contracts, leases on various types of real and personal property, and receivables from credit card agreements. During periods of falling interest rates, mortgage-related and other asset-backed securities, which typically provide the issuer with the right to prepay the security prior to maturity, may be prepaid, which may result in a Fund having to reinvest the proceeds in other investments at lower interest rates. During periods of rising interest rates, the average life of mortgage-related and other asset-backed securities may extend because of slower-than expected principal payments. This may lock in a below market interest rate, increase the security's duration and interest rate sensitivity, and reduce the value of the security. As a result, mortgage-related and other asset-backed securities may have less potential for capital appreciation during periods of declining interest rates than other debt securities of comparable maturities, although they may have a similar risk of decline in market values during periods of rising interest rates. Prepayment rates are difficult to predict and the potential impact of prepayments on the value of a mortgage-related or other asset-backed security depends on the terms of the instrument and can result in significant volatility. The price of a mortgage-related or other asset-backed security also depends on the credit quality and adequacy of the underlying assets or collateral. Mortgage-related or other asset-backed securities issued by non-governmental issuers (such as commercial banks, savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers) will generally entail greater credit risk than obligations guaranteed by the U.S. Govern

ment. Defaults on the underlying assets, if any, may impair the value of a mortgage-related or other asset-backed security. For some asset-backed securities in which a Fund invests, such as those backed by credit card receivables, the underlying cash flows may not be supported by a security interest in a related asset. Moreover, the values of mortgage-related and other asset-backed securities may be substantially dependent on the servicing of the underlying asset pools, and are therefore subject to risks associated with the negligence or malfeasance by their servicers and to the credit risk of their servicers. In certain situations, the mishandling of related documentation may also affect the rights of securities holders in and to the underlying collateral. There may be legal and practical limitations on the enforceability of any security interest granted with respect to underlying assets, or the value of the underlying assets, if any, may be insufficient if the issuer defaults.

Municipal Obligations Risk (principal risk for State Street Income Fund). Issuers, including governmental issuers, may be unable to pay their obligations as they come due. The values of municipal obligations may be adversely affected by local political and economic conditions and developments. In addition, the values of municipal obligations that depend on a specific revenue source to fund their payment obligations may fluctuate as a result of actual or anticipated changes in the cash flows generated by the revenue source or changes in the priority of the municipal obligation to receive the cash flows generated by the revenue source. Municipal obligations may be more susceptible to downgrades or defaults during recessions or similar periods of economic stress. The secondary market for municipal obligations also tends to be less well-developed and less liquid than many other securities markets, which may limit a Fund's ability to sell its municipal obligations at attractive prices, particularly in stressed market conditions. The differences between the price at which an obligation can be purchased and the price at which it can be sold may widen during periods of market distress. Less liquid obligations can become more difficult to value and be subject to erratic price movements. In addition, changes in U.S. federal tax laws or the activity of an issuer may adversely affect the tax-exempt status of municipal obligations. Loss of tax-exempt status may result in a significant decline in the values of such municipal obligations.

Non-U.S. Securities Risk. Investments in securities of non-U.S. issuers (including depositary receipts) entail risks not typically associated with investing in securities of U.S. issuers. Similar risks may apply to securities traded on a U.S. securities exchange that are issued by entities with significant exposure to non-U.S. countries. In certain countries, legal remedies available to investors may be more limited than those available with regard to U.S. investments. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. entity than about a U.S. entity, and many non-U.S. entities are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the United States. The securities of some non-U.S. entities are less liquid and at times more volatile than securities of comparable U.S. entities, and could become subject to sanctions or embargoes that adversely affect a Fund's investment. Non-U.S. transaction costs, such as brokerage commissions and custody costs may be higher than in the U.S. In addition, there may be a possibility of nationalization or expropriation of assets, imposition of currency exchange controls, confiscatory taxation, and diplomatic developments that could adversely affect the values of a Fund's investments in certain non-U.S. countries. Investments in securities of non-U.S. issuers also are subject to foreign political and economic risk not associated with U.S. investments, meaning that political events (civil unrest, national elections, changes in political conditions and foreign relations, imposition of exchange controls and repatriation restrictions), social and economic events (labor strikes, rising inflation) and natural disasters occurring in a country where a Fund invests could cause the Fund's investments to experience gains or losses.

Portfolio Turnover Risk (principal risk for State Street Income Fund). A Fund may engage in frequent trading of its portfolio securities. Fund turnover generally involves a number of direct and indirect costs and expenses to a Fund, including, for example, brokerage commissions, dealer mark-ups and bid/asked spreads, and transaction costs on the sale of securities and reinvestment in other securities. The costs related to increased portfolio turnover have the effect of reducing a Fund's investment return.

Real Estate Sector Risk (principal risk for State Street U.S. Core Equity Fund). There are special risks associated with investment in securities of companies engaged in real property markets, including without limitation REITs and real estate operating companies. An investment in a real property company may be subject to risks similar to those associated with direct ownership of real estate, including, by way of example, the possibility of declines in the value of real estate, losses from casualty or condemnation, and changes in local and general economic conditions, supply and demand, interest rates, environmental liability, zoning laws, regulatory limitations on rents, property taxes, and operating expenses. An investment in a real property company is subject to additional risks, such as poor performance by the manager of the real property company, adverse changes in tax laws, difficulties in valuing and disposing of real estate, and the effect of general declines in stock prices. Some real property companies have limited diversification because they invest in a lim

ited number of properties, a narrow geographic area, or a single type of property. Also, the organizational documents of a real property company may contain provisions that make changes in control of the company difficult and time-consuming. As a shareholder in a real property company, the Fund, and indirectly the Fund's shareholders, would bear their ratable shares of the real property company's expenses and would at the same time continue to pay their own fees and expenses.

REIT Risk (principal risk for State Street U.S. Core Equity Fund). REITs are subject to the risks associated with investing in the securities of real property companies. In particular, REITs may be affected by changes in the values of the underlying properties that they own or operate. Further, REITs are dependent upon specialized management skills, and their investments may be concentrated in relatively few properties, or in a small geographic area or a single property type. REITs are also subject to heavy cash flow dependency and, as a result, are particularly reliant on the proper functioning of capital markets, as well as defaults by borrowers and self-liquidation. A variety of economic and other factors may adversely affect a lessee's ability to meet its obligations to a REIT. In the event of a default by a lessee, the REIT may experience delays in enforcing its rights as a lessor and may incur substantial costs associated with protecting its investments. In addition, a REIT could possibly fail to qualify for favorable tax treatment under the Internal Revenue Code of 1986, as amended (the “Code”), or to maintain its exemptions from registration under the 1940 Act, which could have adverse consequences for the Fund. Investments in REITs are also subject to the risks affecting equity markets generally.

Repurchase Agreement Risk. A repurchase agreement is an agreement to buy a security from a seller at one price and a simultaneous agreement to sell it back to the original seller at an agreed-upon price, typically representing the purchase price plus interest. Repurchase agreements may be viewed as loans made by a Fund which are collateralized by the securities subject to repurchase. A Fund's investment return on such transactions will depend on the counterparty's willingness and ability to perform its obligations under a repurchase agreement. If a Fund's counterparty should default on its obligations and the Fund is delayed or prevented from recovering the collateral, or if the value of the collateral is insufficient, the Fund may realize a loss.

Restricted Securities Risk. A Fund may hold securities that have not been registered for sale to the public under the U.S. federal securities laws pursuant to an exemption from registration. These securities may be less liquid than securities registered for sale to the general public. The liquidity of a restricted security may be affected by a number of factors, including, among others: (i) the creditworthiness of the issuer; (ii) the frequency of trades and quotes for the security; (iii) the number of dealers willing to purchase or sell the security and the number of other potential purchasers; (iv) dealer undertakings to make a market in the security; (v) the nature of any legal restrictions governing trading in the security; and (vi) the nature of the security and the nature of marketplace trades. There can be no assurance that a liquid trading market will exist at any time for any particular restricted security. Also, restricted securities may be difficult to value because market quotations may not be readily available, and the securities may have significant volatility.

Short Sales Risk (principal risk for State Street U.S. Core Equity Fund). The Fund may engage in “short sale” transactions. A short sale involves the sale by a Fund of an instrument or security that it does not own with the hope of purchasing the same security at a later date at a lower price. Short sales are designed to profit from a decline in the price of a security or instrument. A Fund will lose value if the security or instrument that is the subject of a short sale increases in value. This is the opposite of traditional “long” investments where the value of a Fund increases as the value of a portfolio security or instrument increases. The Fund also may enter into a short derivative position through a futures contract, swap agreement, structured note, or short positions on currency forwards.

Risk of Investment in Other Pools. If a Fund invests in another pooled investment vehicle (e.g., a mutual fund or exchange-traded fund), it is exposed to the risk that the other pool will not perform as expected. A Fund is exposed indirectly to all of the risks applicable to an investment in such other pool. In addition, lack of liquidity in the underlying pool could result in its value being more volatile than the underlying portfolio of securities, and may limit the ability of a Fund to sell or redeem its interest in the pool at a time or at a price it might consider desirable. The investment policies and limitations of the other pool may not be the same as those of the Fund; as a result, the Fund may be subject to additional or different risks, or may achieve a reduced investment return, as a result of its investment in another pool. If a pool is an exchange-traded fund or other product traded on a securities exchange or otherwise actively traded, its shares may trade at a premium or discount to their NAV, an effect that might be more pronounced in less liquid markets. A Fund bears its proportionate share of the fees and expenses of any pool in which it invests. The Adviser or an affiliate may serve as investment adviser to a pool in which the Fund may invest, leading to potential conflicts of interest. For example, the Adviser or its affiliates may receive fees based on the amount of assets invested in the pool. Investment by a Fund in the

pool may be beneficial to the Adviser or an affiliate in the management of the pool, by helping to achieve economies of scale or enhancing cash flows. Due to this and other factors, the Adviser may have an incentive to invest a Fund's assets in a pool sponsored or managed by the Adviser or its affiliates in lieu of investments by the Fund directly in portfolio securities, or may have an incentive to invest in the pool over a pool sponsored or managed by others. Similarly, the Adviser may have an incentive to delay or decide against the sale of interests held by a Fund in a pool sponsored or managed by the Adviser or its affiliates. It is possible that other clients of the Adviser or its affiliates will purchase or sell interests in a pool sponsored or managed by the Adviser or its affiliates at prices and at times more favorable than those at which a Fund does so.

Technology Sector Risk (principal risk for State Street U.S. Core Equity Fund). Market or economic factors impacting technology companies and companies that rely heavily on technological advances could have a major effect on the value of the Fund's investments. The value of stocks of technology companies and companies that rely heavily on technology is particularly vulnerable to rapid changes in technology product cycles, rapid product obsolescence, government regulation and competition, both domestically and internationally, including competition from foreign competitors with lower production costs. Technology companies may have limited product lines, markets, financial resources or personnel. Stocks of technology companies and companies that rely heavily on technology, especially those of smaller, less-seasoned companies, tend to be more volatile than the overall market. Technology companies are heavily dependent on patent and intellectual property rights, the loss or impairment of which may adversely affect profitability. Additionally, companies in the technology sector may face dramatic and often unpredictable changes in growth rates and competition for the services of qualified personnel.

U.S. Government Securities Risk (principal risk for the State Street Income Fund). U.S. government securities, such as Treasury bills, notes and bonds and mortgage-backed securities guaranteed by the Government National Mortgage Association (“Ginnie Mae”), are supported by the full faith and credit of the United States; others are supported by the right of the issuer to borrow from the U.S. Treasury; others are supported by the discretionary authority of the U.S. government to purchase the agency's obligations; and still others are supported only by the credit of the issuing agency, instrumentality, or enterprise. Although U.S. government-sponsored enterprises such as the Federal Home Loan Mortgage Corporation (“Freddie Mac”) and the Federal National Mortgage Association (“Fannie Mae”) may be chartered or sponsored by Congress, they are not funded by Congressional appropriations, and their securities are not issued by the U.S. Treasury nor supported by the full faith and credit of the U.S. government. There is no assurance that the U.S. government would provide financial support to its agencies and instrumentalities if not required to do so. In addition, certain governmental entities have been subject to regulatory scrutiny regarding their accounting policies and practices and other concerns that may result in legislation, changes in regulatory oversight and/or other consequences that could adversely affect the credit quality, availability, or investment character of securities issued by these entities. The value and liquidity of U.S. government securities may be affected adversely by changes in the ratings of those securities. Securities issued by the U.S. Treasury historically have been considered to present minimal credit risk. The downgrade in the long-term U.S. credit rating by at least one major rating agency has introduced greater uncertainty about the ability of the U.S. to repay its obligations. A further credit rating downgrade or a U.S. credit default could decrease the value and increase the volatility of a Fund's investments.

Valuation Risk (principal risk for State Street Income Fund). This may occur more often in times of market turmoil or reduced liquidity. There are multiple methods that can be used to value a portfolio holding when market quotations are not readily available. The value established for any portfolio holding at a point in time might differ from what would be produced using a different methodology or if it had been priced using market quotations. Portfolio holdings that are valued using techniques other than market quotations, including “fair valued” securities, may be subject to greater fluctuation in their valuations from one day to the next than if market quotations were used. Technological issues or other service disruption issues involving third-party service providers may cause a Fund to value its investments incorrectly. In addition, there is no assurance that a Fund could sell or close out a portfolio position for the value established for it at any time, and it is possible that a Fund would incur a loss because a portfolio position is sold or closed out at a discount to the valuation established by the Fund at that time. Investors who purchase or redeem Fund Shares on days when the Fund is holding fair-valued investments may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the Fund had not fair-valued the holding(s) or had used a different valuation methodology.

Value Stock Risk (principal risk for State Street U.S. Core Equity Fund). Value stocks present the risk that they may decline in price or never reach their expected full market value, either because the market fails to recognize the stock's intrinsic worth or SSGA FM overestimates the stock's expected value. Value stocks may underperform growth stocks and stocks in other broad style categories (and the stock market as a whole) over any period of time and may shift in

and out of favor with investors generally, sometimes rapidly, depending on changes in market, economic, and other factors. As a result, at times when it holds substantial investments in value stocks a Fund may underperform other investment portfolios that invest more broadly or that favor different investment styles.

Additional Information About Non-Principal Investment Strategies and Risks

The investments described below reflect the Funds' current practices. In addition to the principal risks described above, other risks are described in some of the descriptions of the investments below:

Conflicts of Interest Risk. An investment in a Fund will be subject to a number of actual or potential conflicts of interest. For example, the Adviser or its affiliates may provide services to a Fund, such as securities lending agency services, custodial, administrative, bookkeeping, and accounting services, transfer agency and shareholder servicing, securities brokerage services, and other services for which the Fund would compensate the Adviser and/or such affiliates. The Funds may invest in other pooled investment vehicles sponsored, managed, or otherwise affiliated with the Adviser. There is no assurance that the rates at which a Fund pays fees or expenses to the Adviser or its affiliates, or the terms on which it enters into transactions with the Adviser or its affiliates will be the most favorable available in the market generally or as favorable as the rates the Adviser or its affiliates make available to other clients. Because of its financial interest, the Adviser will have an incentive to enter into transactions or arrangements on behalf of a Fund with itself or its affiliates in circumstances where it might not have done so in the absence of that interest, provided that the Adviser will comply with applicable regulatory requirements.

The Adviser and its affiliates serve as investment adviser to other clients and may make investment decisions that may be different from those that will be made by the Adviser on behalf of the Funds. For example, the Adviser may provide asset allocation advice to some clients that may include a recommendation to invest in or redeem from particular issuers while not providing that same recommendation to all clients invested in the same or similar issuers. The Adviser may (subject to applicable law) be simultaneously seeking to purchase (or sell) investments for a Fund and to sell (or purchase) the same investment for accounts, funds, or structured products for which it serves as asset manager, or for other clients or affiliates. The Adviser and its affiliates may invest for clients in various securities that are senior, pari passu or junior to, or have interests different from or adverse to, the securities that are owned by a Fund. The Adviser or its affiliates, in connection with its other business activities, may acquire material nonpublic confidential information that may restrict the Adviser from purchasing securities or selling securities for itself or its clients (including the Funds) or otherwise using such information for the benefit of its clients or itself.

The foregoing does not purport to be a comprehensive list or complete explanation of all potential conflicts of interests which may affect a Fund. A Fund may encounter circumstances, or enter into transactions, in which conflicts of interest that are not listed or discussed above may arise.

Cybersecurity Risk. With the increased use of technologies such as the Internet and the dependence on computer systems to perform business and operational functions, funds (such as the Funds) and their service providers (including the Adviser) may be prone to operational and information security risks resulting from cyber-attacks and/or technological malfunctions. In addition, the global spread of COVID-19 caused the Fund and its service providers to implement business continuity plans, including widespread use of work-from-home arrangements. Furthermore, geopolitical tensions may have increased the scale and sophistication of deliberate cybersecurity attacks, particularly those from nation-states or from entities with nation-state backing. In general, cyber-attacks are deliberate, but unintentional events may have similar effects. Cyber-attacks include, among others, stealing or corrupting data maintained online or digitally, preventing legitimate users from accessing information or services on a website, releasing confidential information without authorization, and causing operational disruption. Successful cyber-attacks against, or security breakdowns of, a Fund,the Portfolio, the Adviser or a custodian, transfer agent, or other affiliated or third-party service provider may adversely affect a Fund or its shareholders. For instance, cyber-attacks or technical malfunctions may interfere with the processing of shareholder or other transactions, affect a Fund's ability to calculate its NAV, cause the release of private shareholder information or confidential Fund information, impede trading, cause reputational damage, and subject a Fund to regulatory fines, penalties or financial losses, reimbursement or other compensation costs, and additional compliance costs. Cyber-attacks or technical malfunctions may render records of Fund assets and transactions, shareholder ownership of Fund Shares, and other data integral to the functioning of a Fund inaccessible or inaccurate or incomplete. A Fund may also incur substantial costs for cybersecurity risk management in order to prevent cyber incidents in the future. A Fund and its shareholders could be negatively impacted as a result. While the Adviser has established business continuity plans and systems designed to minimize the risk of cyber-attacks through the use of technology, processes and con

trols, there are inherent limitations in such plans and systems, including the possibility that certain risks have not been identified, given the evolving nature of this threat. Each Fund relies on third-party service providers for many of its day-to-day operations, and will be subject to the risk that the protections and protocols implemented by those service providers will be ineffective to protect the Fund from cyber-attack. The Adviser does not control the cybersecurity plans and systems put in place by third-party service providers, and such third-party service providers may have limited indemnification obligations to the Adviser or the Funds. Similar types of cybersecurity risks or technical malfunctions also are present for issuers of securities in which each Fund invests, which could result in material adverse consequences for such issuers, and may cause a Fund's investment in such securities to lose value.

Money Market Risk. An investment in a money market fund is not a deposit of any bank and is not insured or guaranteed by the FDIC or any other government agency. Certain money market funds seek to preserve the value of their shares at $1.00 per share, although there can be no assurance that they will do so, and it is possible to lose money by investing in such a money market fund. A major or unexpected change in interest rates or a decline in the credit quality of an issuer or entity providing credit support, an inactive trading market for money market instruments, or adverse market, economic, industry, political, regulatory, geopolitical, and other conditions could cause the share price of such a money market fund to fall below $1.00. It is possible that such a money market fund will issue and redeem shares at $1.00 per share at times when the fair value of the money market fund's portfolio per share is more or less than $1.00. The SEC has adopted amendments to money market fund regulation that, among other things, increase the daily and weekly liquid asset requirements. Such amendments may limit the Funds' investment flexibility and reduce its ability to generate returns. None of State Street Corporation, State Street Bank and Trust Company (“State Street”), State Street Global Advisors, Inc., SSGA Funds Management, Inc. or their affiliates (“State Street Entities”) guarantee the value of an investment in a money market fund at $1.00 per share. Investors should have no expectation of capital support to a money market fund from State Street Entities. Other money market funds price and transact at a “floating” NAV that will fluctuate along with changes in the market-based value of fund assets. Shares sold utilizing a floating NAV may be worth more or less than their original purchase price. Recent changes in the regulation of money market funds may affect the operations and structures of money market funds. A money market fund may be permitted or required to impose redemption fees during times of market stress.

Temporary Defensive Positions. In response to actual or perceived adverse market, economic, political, or other conditions, a Fund may (but will not necessarily), without notice, depart from its principal investment strategies by temporarily investing for defensive purposes. While investing defensively, a Fund may maintain a substantial portion of its assets in cash, on which a Fund may earn little, if any, income. If a Fund invests for defensive purposes, it may not achieve its investment objective. In addition, the defensive strategy may not work as intended.

Portfolio Holdings Disclosure

The Funds' portfolio holdings disclosure policy is described in the Statement of Additional Information (“SAI”).

Management and Organization

Each Fund is a separate, diversified series of the State Street Institutional Investment Trust (the “Trust”), which is an open-end management investment company organized as a business trust under the laws of the Commonwealth of Massachusetts.

Investment Adviser

SSGA FM serves as the investment adviser to each Fund and, subject to the oversight of the Board, is responsible for the investment management of each Fund. The Adviser provides an investment management program for each Fund and manages the investment of each Fund's assets. In addition, the Adviser provides administrative, compliance and general management services to each Fund. The Adviser is a wholly-owned subsidiary of State Street Global Advisors, Inc., which itself is a wholly-owned subsidiary of State Street Corporation. The Adviser is registered with the SEC under the Investment Advisers Act of 1940, as amended. The Adviser and certain other affiliates of State Street Corporation make up State Street Global Advisors (“SSGA”). SSGA is one of the world's largest institutional money managers and the investment management arm of State Street Corporation. As of September 30, 2023, the Adviser managed approximately $876.06 billion in assets and SSGA managed approximately $3.69 trillion in assets. The Adviser's principal business address is One Iron Street, Boston, Massachusetts 02210. GE Asset Management Incorporated (“GEAM”) served as each Fund's investment adviser until 2016, when State Street Corporation, the ultimate parent company of the Adviser, acquired substantially all of the assets of GEAM.

Each Fund has entered into an investment advisory agreement with the Adviser, pursuant to which the Adviser will manage the Fund's assets, for compensation paid at an annual rate of 0.13% of the State Street Income Fund's average daily net assets and 0.12% of the State Street U.S. Core Equity Fund's average daily net assets. For the year ended September 30, 2023, State Street Income Fund's effective management fee paid was 0.13% and State Street U.S. Core Equity Fund's effective management fee paid was 0.12%, each as a percentage of the Fund's average daily net assets.

A discussion regarding the Board's consideration of the Funds' Investment Advisory Agreement is provided in the Funds' Annual Report to Shareholders for the period ended September 30, 2023.

The Adviser manages the Funds' using a team of investment professionals. The team approach is used to create an environment that encourages the flow of investment ideas. The portfolio managers within the team work together in a cohesive manner to develop and enhance techniques that drive the investment process for the respective investment strategy. This approach requires portfolio managers to share a variety of responsibilities, including investment strategy and analysis, while retaining responsibility for the implementation of the strategy within any particular portfolio. The approach also enables the team to draw upon the resources of other groups within SSGA. The portfolio management team is overseen by the SSGA Investment Committee.

The professionals primarily responsible for the day-to-day management of each Fund include the following:


Portfolio Manager(s)	Fund
Matthew Nest and James Palmieri	State Street Income Fund
Michael Solecki, Paul Nestro and Chris Sierakowski	State Street U.S. Core Equity Fund

Matthew Nest, CFA, is a Managing Director of SSGA and the Adviser and the Global Head of Active Fixed Income. In this capacity, he is responsible for global active rates, investment grade credit, multi-sector portfolio solutions, insurance, currency, municipal, and structured credit strategies. Prior to joining SSGA in 2016, Mr. Nest spent sixteen years at PIMCO in a number of functions including portfolio management, strategy and business development. He has worked in the U.S., Sydney, Singapore and Hong Kong. He started his career at Bank of America and has been working in the investment industry since 1999. Mr. Nest has a Bachelor of Science in Economics from Arizona State University and a Master of Business Administration from the University of Chicago's Booth School of Business. He earned the Chartered Financial Analyst (CFA) designation and is a member of the CFA Institute.

Paul Nestro, CFA, is a Managing Director of SSGA and the Adviser and the Director of Fundamental Growth and Core Equity Research. He is also the Portfolio Manager for the SSGA Global Innovation strategy. Previously, he was the Co-Portfolio Manager for European Equity, Emerging Markets Equity, International Equity, and International Small Cap Equity strategies. He also served as the team's analyst covering the metals and mining sector and as an analyst for a

Global Equity mutual fund. Mr. Nestro joined SSGA in July 2016 through the acquisition of GEAM by the ultimate parent company of SSGA. After completing GE's Financial Management Program, he joined the Financial Planning & Analysis team at GEAM, and has been in the investment industry since 1993. Mr. Nestro has a Bachelor of Arts in Finance from Michigan State University and is a holder of the Chartered Financial Analyst (CFA) designation.

James Palmieri, CFA, is a Managing Director of SSGA and the Adviser, a Senior Portfolio Manager, and Head of Structured Credit for the Fundamental Active Fixed Income Team. In his role, he is the lead portfolio manager and trader for the Structured Products Group servicing all total rate of return and insurance accounts managed in Stamford, CT. In addition to his portfolio management responsibilities, Mr. Palmieri is a member of the Fixed Income Currency and Cash Senior Leadership Team, and the Fundamental Active Core and Core Plus Fixed Income Team. He joined SSGA in 2016 through the acquisition of GEAM by the ultimate parent company of SSGA. Prior to joining SSGA, Mr. Palmieri worked at GEAM for eleven years as a senior portfolio manager and trader for all fixed income total rate of return and insurance accounts for GE. Prior to joining GEAM, he worked at Constitution State Corporate Credit Union for one year as an investment director and CIGNA Investment Management for five years as a fixed income portfolio manager. He received his Bachelor of Science from Central Connecticut State University, is a Chartered Financial Analyst (CFA) charter holder, and has twenty years of investment experience.

Chris Sierakowski, CFA, is a Managing Director of SSGA and the Adviser and a Portfolio Manager in the Fundamental Growth and Core U.S. Equity Group. Mr. Sierakowski joined SSGA through the acquisition of GEAM by the ultimate parent company of SSGA in July 2016. Prior to joining SSGA, Mr. Sierakowski served in various investment roles at GEAM since 1999, including portfolio management and as a research analyst providing coverage for the software, computer hardware, semiconductors, business services, and payments industries. Prior to GEAM, Mr. Sierakowski spent several years in consulting and as an officer in the U.S. Army. Mr. Sierakowski has a Bachelor of Science in Economics from the United States Military Academy and a Master of Business Administration in Finance, Strategy, and Accounting from the University of Chicago Booth School of Business. He earned the Chartered Financial Analyst (CFA) designation and has been a member of the CFA Institute since 2002.

Michael Solecki, CFA, is a Senior Managing Director of SSGA and the Adviser, Portfolio Manager and the Chief Investment Officer for Fundamental Equity. Previously, Mr. Solecki was Chief Investment Officer of Fundamental Growth and Core Equity at SSGA. He joined SSGA in July 2016 through the acquisition of GEAM by the ultimate parent company of SSGA. Previously at GEAM, as part of the International Equity team, he held a variety of leadership roles including Director of Research and Chief Investment Officer. He joined GEAM in 1991 as an equity research analyst in International Equity after completing GE's Financial Management Program where he had financial assignments at GE Energy, GE Capital and GEAM. Prior to GE, he worked for Monarch Capital Corporation. He holds a Bachelor of Science in Finance from Western New England College and a Master of Business Administration from Fordham University. He is a holder of the Chartered Financial Analyst (CFA) designation and is a member of the CFA Institute and the CFA Society New York. He is also a Board member at SoundWaters in Stamford, Connecticut.

Additional information about the portfolio managers' compensation, other accounts managed by the portfolio managers, and the portfolio managers' ownership of the Funds is available in the SAI.

Other Fund Services

The Administrator, Sub-Administrator and Custodian

SSGA FM serves as administrator of each Fund. State Street serves as the custodian and sub-administrator for the Funds for a fee that is paid by the Funds.

The Transfer Agent and Dividend Disbursing Agent

U.S. Bancorp Fund Services, LLC is the Funds' transfer agent and dividend disbursing agent (the “Transfer Agent”).

The Distributor

State Street Global Advisors Funds Distributors, LLC serves as the Funds' distributor (“SSGA FD”) pursuant to the Distribution Agreement between SSGA FD and the Trust.

Additional Information

The Trustees of the Trust oversee generally the operations of the Funds and the Trust. The Trust enters into contractual arrangements with various parties, including, among others, the Funds' investment adviser, custodian, transfer agent, and accountants, who provide services to the Funds. Shareholders are not parties to any such contractual arrangements or intended beneficiaries of those contractual arrangements, and those contractual arrangements are not intended to create in any shareholder any right to enforce them directly against the service providers or to seek any remedy under them directly against the service providers.

This Prospectus provides information concerning the Trust and the Funds that you should consider in determining whether to purchase shares of the Funds. Neither this Prospectus, nor the related SAI, is intended, or should be read, to be or to give rise to an agreement or contract between the Trust or the Funds and any investor, or to give rise to any rights in any shareholder or other person other than any rights under federal or state law that may not be waived.

Shareholder Information

Determination of Net Asset Value

Each Fund determines its NAV per share once each business day as of the scheduled close of regular trading on the New York Stock Exchange (the “NYSE”). Pricing does not occur on NYSE holidays. A business day is one on which the NYSE is open for regular trading. The Federal Reserve is closed on certain holidays on which the NYSE is open. These holidays are Columbus Day and Veterans Day. On these holidays, you will not be able to purchase shares by wiring Federal Funds because Federal Funds wiring does not occur on days when the Federal Reserve is closed. In unusual circumstances, such as an emergency or an unscheduled close or halt of trading on the NYSE, the time at which share prices are determined may be changed. The NAV per share is based on the market value of the investments held in a Fund. The NAV of each class of a Fund's Shares is calculated by dividing the value of the assets of the Fund attributable to that class less the liabilities of the Fund attributable to that class by the number of shares in the class outstanding. Each Fund values each security or other investment pursuant to guidelines adopted by the Board. The Board has appointed the Adviser as the valuation designee to fair value securities or other investments pursuant to procedures approved by the Funds' Board, under certain limited circumstances. For example, fair value pricing may be used when market quotations are not readily available or reliable, such as when (i) trading for a security is restricted; or (ii) a significant event, as determined by the Adviser, that may affect the value of one or more securities or other investments held by a Fund occurs after the close of a related exchange but before the determination of a Fund's NAV. Attempts to determine the fair value of securities or other investments introduce an element of subjectivity to the pricing of securities or other investments. As a result, the price of a security or other investment determined through fair valuation techniques may differ from the price quoted or published by other sources and may not accurately reflect the price a Fund would have received had it sold the investment. To the extent that a Fund invests in the shares of other registered open-end investment companies that are not traded on an exchange (mutual funds), such shares are valued at their published NAVs per share as reported by the funds. The prospectuses of these funds explain the circumstances under which the funds will use fair value pricing and the effects of using fair value pricing.

Investing in Fund Shares

Purchasing Shares

This Prospectus is intended for use only by the Plan and Plan participants.

General Electric Retirement Savings Plan Participants

Plan participants should consult the Plan's Supplemental Information document and other materials describing the Plan for information about how to invest in the Fund investment options offered through the Plan. The Funds do not control the contents of the Plan's Supplemental Information document or other materials describing the Plan.

The Plan

The Plan purchases and redeems shares of the Fund for its asset value without any sales or redemption charge.

The Plan may purchase shares directly through the transfer agent by wiring federal funds from a U.S. banking institution to:

U.S. Bank, N.A.
777 East Wisconsin Avenue
Milwaukee, WI 53202-5207
ABA #075000022
Credit: U.S. Bancorp Fund Services, LLC
Account #112-952-137

Further Credit:

(name of Fund to be purchased)
(shareholder registration)
(shareholder account number)

Wired funds must be received prior to 4:00 p.m. Eastern time to be eligible for same day pricing. The Funds and U.S. Bank, N.A. are not responsible for the consequences of delays resulting from the banking or Federal Reserve wire system, or from incomplete wiring instructions.

Requests received in good order will be executed at the NAV next calculated after receipt of investment or transaction instructions. Purchase and redemption orders are executed only on days when the NYSE is open for trading. If the NYSE closes early, the deadlines for purchase and redemption orders will be accelerated to the earlier closing time.

The Funds may reject any purchase order or exchange request for any reason or no reason and without prior notice.

Trade Dates-Purchases

The trade date for any purchase request received in good order will depend on the day and time the State Street Funds receive your request, the manner in which you are paying, and the type of fund you are purchasing. Each State Street Fund's NAV is calculated only on business days, that is, those days that the NYSE is open for regular trading. Purchase orders are processed at the NAV next determined after the Fund accepts a purchase order.

Refused or Rejected Purchase Requests.

The State Street Funds reserve the right to stop selling Fund Shares or to reject any purchase request at any time and without notice. This right also includes the right to reject any purchase request because of a history of frequent trading by the investor or because the purchase may negatively affect a Fund's operation or performance.

Redeeming Shares

General Electric Retirement Savings Plan Participants

Plan participants should consult the Plan's Supplemental Information document and other materials describing the Plan for information about how to redeem Fund shares offered through the Plan. The Funds do not control the contents of the Plan's Supplemental Information document or other materials describing the Plan.

The Plan

By Mail:

Send a signed letter to:

State Street Global Advisors
c/o U.S. Bank Global Fund Services
P.O. Box 701
Milwaukee, WI 53201-0701

The letter should include information necessary to process your request as described below. The Fund may require a medallion guarantee in certain circumstances. See “Medallion Guarantees” below.

By Overnight:

State Street Global Advisors
c/o U.S. Bank Global Fund Services
615 East Michigan Street
Milwaukee, WI 53202-5207

By Telephone:

Call (800) 242-0134

The Funds will need the following information to process your redemption request:

➢ name(s) of account owners;

➢ account number(s);

➢ the name of the Fund;

➢ your daytime telephone number; and

➢ the dollar amount or number of shares being redeemed.

On any day that the Funds calculate their NAV earlier than normal, the Funds reserve the right to adjust the times noted above for purchasing and redeeming shares.

If you choose to redeem shares by sending instructions by regular mail, they will not be deemed received in good order until they are released by the post office and redelivered to the Transfer Agent's physical location at 615 East Michigan Street in Milwaukee, WI 53202. There will be a time lag, which may be one or more days, between regular mail receipt at the post office box and redelivery to such physical location in Milwaukee, and a Fund's NAV may change over those days. You might consider using express rather than regular mail if you believe the time of receipt of your transaction request to be sensitive.

The transfer agent may temporarily delay for more than seven days the disbursement of redemption proceeds from the Fund account of a “Specified Adult” (as defined in Financial Industry Regulatory Authority, Inc. (“FINRA”) Rule 2165) based on a reasonable belief that financial exploitation of the Specified Adult has occurred, is occurring, has been attempted, or will be attempted, subject to certain conditions.

Trade Date-Redemptions

The trade date for any redemption request received in good order will depend on the day and time the State Street Funds receive your request in good order and the manner in which you are redeeming.

Your redemption will be executed using the NAV as calculated on the trade date. NAVs are calculated only on days that the NYSE is open for regular trading (a business day). If the redemption request is received in good order by the State Street Funds on a business day before the close of regular trading on the NYSE (ordinarily 4 p.m., Eastern time), the request will be processed the same day using that day's NAV. If the redemption request is received in good order on a business day after the close of regular trading on the NYSE, or on a non-business day, the request will be processed the next business day.

How to Receive Redemption Proceeds

Regardless of the method the Funds use to make a redemption payment, the Funds typically expect to pay out redemption proceeds on the next business day after a redemption request is received in good order. The State Street Funds reserve the right to pay for redeemed shares within seven days after receiving a redemption order if, in the judgment of the Adviser, an earlier payment could adversely affect a Fund.

Under normal circumstances, each Fund expects to meet redemption requests by using cash or cash equivalents in its portfolio and/or selling portfolio assets to generate cash. The Funds also may pay redemption proceeds using cash obtained through borrowing arrangements (including under the Funds' line of credit, which is shared across all registered funds advised by SSGA FM (other than money market funds)) that may be available from time to time.

The right of any investor to receive payment with respect to any redemption may be suspended or the payment of the redemption proceeds postponed beyond 7 days in accordance with Section 22(e) of the 1940 Act and the rules thereunder, including during any period in which the NYSE is closed (other than weekends or holidays) or trading on the NYSE is restricted or if an emergency exists as a result of which disposal by a Fund of securities owned by it is not reasonably practicable or it is not reasonably practicable for a Fund fairly to determine the value of its net assets. In addition, the SEC may by order permit suspension of redemptions for the protection of shareholders of a Fund.

A Fund may pay all or a portion of your redemption proceeds by giving you securities (for example, if the Fund reasonably believes that a cash redemption may have a substantial impact on the Fund and its remaining shareholders). You may pay transaction costs to dispose of the securities, and you may receive less for them than the price at which they were valued for purposes of the redemption. In addition, you will be subject to the market risks associated with such securities until such time as you choose to dispose of the security.

During periods of deteriorating or stressed market conditions, when an increased portion of a Fund's portfolio may be comprised of less liquid investments, or during extraordinary or emergency circumstances, a Fund may be more likely to pay redemption proceeds with cash obtained through short-term borrowing arrangements (if available) or by giving you securities.

Frequent-Trading Limits

Frequent, short-term trading, abusive trading practices and market timing (together, “Excessive Trading”), often in response to short-term fluctuations in the market, are not knowingly permitted by the State Street Funds. The State Street Funds do not accommodate frequent purchases and redemptions of Fund Shares by Fund shareholders. Excessive Trading into and out of a State Street Fund may harm a Fund's performance by disrupting portfolio management strategies and by increasing expenses. These expenses are borne by all Fund shareholders, including long-term investors who do not generate such costs.

Excessive Trading activity is generally evaluated based on roundtrip transactions in an account. A “roundtrip” transaction is defined generally as a purchase or exchange into a Fund followed, or preceded, by a redemption or exchange out of the same Fund within 30 days. A State Street Fund may, in its discretion, determine to apply a time period other than 30 days in connection with identifying roundtrip transactions. Shareholders with one or more roundtrip transactions may, in the discretion of a State Street Fund, be blocked from making additional purchases or exchanges in any State Street Fund for a period of time. A State Street Fund has discretion to determine that action is not necessary if it determines that a pattern of trading is not abusive or harmful to the affected Fund in a material way. Fund size and/or transaction size may be considered in evaluating any roundtrip transaction.

The Board of Trustees of the State Street Funds has adopted a “Market Timing/Excessive Trading Policy” (the “Policy”) to discourage Excessive Trading. Under the Policy, the State Street Funds reserve the right to reject any exchanges or purchase orders by any shareholder engaging in Excessive Trading activities.

As a means to protect each State Street Fund and its shareholders from Excessive Trading:

•

The State Street Funds' transfer agent compiles, monitors and reports account-level information on omnibus and underlying shareholder/participant activity. Depending on the account type, monitoring will be performed on a daily, monthly, quarterly and/or annual basis;

•

The State Street Funds' distributor has obtained information from each Financial Intermediary holding shares in an omnibus account with the State Street Funds regarding whether the Financial Intermediary has adopted and maintains procedures that are reasonably designed to protect the Funds against harmful short-term trading; and

•

With respect to State Street Funds that invest in securities that trade on foreign markets, pursuant to the State Street Funds' fair valuation procedures, pricing adjustments may be made based on information received from a third-party, multi-factor fair valuation pricing service.

The State Street Funds' distributor has detailed procedures that document the transparency oversight and monitoring processes performed by the State Street Funds' transfer agent.

While the State Street Funds attempt to discourage Excessive Trading, there can be no guarantee that it will be able to identify investors who are engaging in Excessive Trading or limit their trading practices. Additionally, frequent trades of small amounts may not be detected. The State Street Funds recognize that it may not always be able to detect or prevent Excessive Trading or other activity that may disadvantage the Funds or their shareholders.

A State Street Fund shareholder's right to purchase shares through an automatic investment plan or redeem shares in full (or in part through a systematic withdrawal plan) are unaffected by Excessive Trading restrictions.

Dividends, Distributions and Tax Considerations

Net investment income dividends and capital gain distributions of the Funds will typically be declared and paid annually. Any investment income and capital gains that have not been distributed by December of each calendar year are generally distributed at such time. Dividends and capital gain distributions made by a Fund to the Plan will be automatically reinvested in shares of the Fund at the Fund's NAV. There are no fees or charges to reinvest dividends or distributions.

Taxes

Each Fund has elected to be treated as a regulated investment company and intends each year to qualify and to be eligible to be treated as such. A regulated investment company generally is not subject to tax at the corporate level on income and gains that are timely distributed to shareholders. In order to qualify and be eligible for treatment as a regulated investment company, a Fund must, among other things, satisfy diversification, 90% gross income and distribution requirements. A Fund's failure to qualify as a regulated investment company would result in corporate level taxation, and consequently, a reduction in income available for distribution to shareholders. Each Fund is currently treated as a “personal holding company” and will potentially need to comply with additional requirements with respect to its distributions to shareholders in order to avoid a fund-level tax under the personal holding company rules. Please see Taxation of the Funds in the SAI for further information.

Since the Plan holds Fund Shares on behalf of Plan participants, no discussion is included herein as to the U.S. federal income tax consequences to the Plan or Plan participants. For information concerning the federal tax consequences to Plan participants, consult the Your Benefits Handbook — Retirement Income Benefits (including updates) and any other materials describing Plan tax matters.

State Street Income Fund

Financial Highlights

Selected data based on a share outstanding throughout the periods indicated

	Year Ended 9/30/23	Year Ended 9/30/22	Period Ended 9/30/21(a)(b)(c)	Year Ended 12/31/20(a)(b)	Year Ended 12/31/19(a)(b)	Year Ended 12/31/18(a)(b)
Net asset value, beginning of period	$9.69	$12.08	$12.42	$11.85	$11.14	$11.55
Income/(loss) from investment operations:
Net investment income	0.33 (d)	0.23 (d)	0.17 (d)	0.26 (d)	0.31 (d)	0.32 (d)
Net realized and unrealized gains/(losses) on investments	(0.26 )	(2.02 )	(0.29 )	0.69	0.72	(0.40 )
Total income/(loss) from investment operations	0.07	(1.79 )	(0.12 )	0.95	1.03	(0.08 )
Less distributions from:
Net investment income	(0.37 )	(0.27 )	(0.22 )	(0.34 )	(0.32 )	(0.33 )
Net realized gains	—	(0.33 )	—	(0.04 )	—	—
Total distributions	(0.37 )	(0.60 )	(0.22 )	(0.38 )	(0.32 )	(0.33 )
Net asset value, end of period	$9.39	$9.69	$12.08	$12.42	$11.85	$11.14
Total Return(e)	0.57 %	(15.48 )%	(0.93 )%(f)	8.20 %	9.38 %	(0.75 )%
Ratios/Supplemental Data:
Net assets, end of period (in thousands)	$1,312,814	$1,432,739	$1,908,411	$2,084,815	$2,024,704	$1,992,169
Ratios to average net assets:
Net expenses	0.19 %	0.20 %	0.19 %(g)	0.17 %	0.17 %	0.17 %
Gross expenses	0.19 %	0.20 %	0.19 %(g)	0.17 %	0.17 %	0.17 %
Net investment income	3.34 %	2.07 %	1.85 %(g)	2.16 %	2.67 %	2.86 %
Portfolio turnover rate	32 %(h)	48 %(h)	59 %(f)(h)	110 %(h)	422 %	223 %

Notes to Financial Highlights
(a)	Beginning with the year ended September 30, 2022, the Fund was audited by Ernst & Young LLP. The previous periods were audited by another independent registered public accounting firm.
(b)	Financial information from January 1, 2018 until May 24, 2021 is for the GE RSP Income Fund, which was reorganized into the State Street Income Fund effective May 24, 2021.
(c)	Effective April 13, 2021 the Board of Trustees approved a change in fiscal year end for the Fund from December 31 to September 30.
(d)	Per share values have been calculated using the average shares method.
(e)	Total returns are historical and assume changes in share price, reinvestment of dividends and capital gains distributions. Past performance does not guarantee future results.
(f)	Not annualized.
(g)	Annualized for periods less than one year.
(h)	The portfolio turnover calculated for the periods ended, September 30, 2023, September 30, 2022, September 30, 2021 and December 31, 2020 did not include To-Be-Announced transactions and, if it had, the portfolio turnover would have been 262%, 163%, 134% and 304%, respectively.

State Street U.S. Core Equity Fund

Financial Highlights

Selected data based on a share outstanding throughout the periods indicated

	Year Ended 9/30/23	Year Ended 9/30/22	Period Ended 9/30/21(a)(b)(c)	Year Ended 12/31/20(a)(b)	Year Ended 12/31/19(a)(b)	Year Ended 12/31/18(a)(b)
Net asset value, beginning of period	$56.53	$76.83	$66.39	$57.30	$46.05	$52.45
Income/(loss) from investment operations:
Net investment income	0.75 (d)	0.77 (d)	0.54 (d)	0.77 (d)	0.78 (d)	0.77 (d)
Net realized and unrealized gains/(losses) on investments	11.20	(11.27 )	9.90	12.86	14.07	(2.41 )
Total income/(loss) from investment operations	11.95	(10.50 )	10.44	13.63	14.85	(1.64 )
Less distributions from:
Net investment income	(0.81 )	(0.77 )	—	(0.81 )	(0.77 )	(0.81 )
Net realized gains	(4.62 )	(9.03 )	—	(3.73 )	(2.83 )	(3.95 )
Total distributions	(5.43 )	(9.80 )	—	(4.54 )	(3.60 )	(4.76 )
Net asset value, end of period	$63.05	$56.53	$76.83	$66.39	$57.30	$46.05
Total Return(e)	22.53 %	(16.76 )%	15.73 %(f)	23.82 %	32.22 %	(3.05 )%
Ratios/Supplemental Data:
Net assets, end of period (in thousands)	$5,869,302	$5,198,625	$6,795,684	$6,229,783	$5,541,415	$4,700,274
Ratios to average net assets:
Net expenses	0.14 %	0.16 %	0.15 %(g)	0.14 %	0.14 %	0.14 %
Gross expenses	0.14 %	0.16 %	0.15 %(g)	0.14 %	0.14 %	0.14 %
Net investment income	1.23 %	1.11 %	0.99 %(g)	1.29 %	1.44 %	1.41 %
Portfolio turnover rate	38 %	30 %	27 %(f)	37 %	31 %	40 %

Notes to Financial Highlights
(a)	Beginning with the year ended September 30, 2022, the Fund was audited by Ernst & Young LLP. The previous periods were audited by another independent registered public accounting firm.
(b)	Financial information from January 1, 2018 until May 24, 2021 is for the GE RSP U.S. Equity Fund, which was reorganized into the State Street U.S. Core Equity Fund effective May 24, 2021.
(c)	Effective April 13, 2021 the Board of Trustees approved a change in fiscal year end for the Fund from December 31 to September 30.
(d)	Per share values have been calculated using the average shares method.
(e)	Total returns are historical and assume changes in share price, reinvestment of dividends and capital gains distributions. Past performance does not guarantee future results.
(f)	Not annualized.
(g)	Annualized for periods less than one year.

For more information about the Funds:

The Funds' SAI includes additional information about the Funds and is incorporated by reference into this document. Additional information about the Funds' investments will be available in the Funds' most recent annual and semi-annual reports to shareholders. The Funds' SAI is available, without charge, upon request. The Funds' annual and semi-annual reports will be available, without charge, upon request. Shareholders in the Funds may make inquiries to the Funds to receive such information by calling (800) 242-0134 or the customer service center at the telephone number shown in the accompanying contract prospectus, if applicable. Each Fund's Prospectus and SAI are available, and the annual and semi-annual reports to shareholders will be available, free of charge, on the Funds' website at www.ssga.com.

Reports and other information about the Funds are available free of charge on the EDGAR Database on the SEC's Internet site at http://www.sec.gov. Copies of this information also may be obtained, after paying a duplicating fee, by electronic request at the following E-mail address: [email protected].

SSGA Funds Management, Inc

ONE IRON STREET

BOSTON, MASSACHUSETTS 02210

GM-PROIThe State Street Institutional Investment Trust's Investment Company Act File Number is 811-09819.

Online:	www.ssga.com	24 hours a day, 7 days a week
Phone:	(800) 242-0134

Regular mail	Overnight/ Registered, Express, Certified Mail
State Street Global Advisors c/o U.S. Bank Global Fund Services P.O. Box 701 Milwaukee, WI 53201‐0701	State Street Global Advisors c/o U.S. Bank Global Fund Services 615 East Michigan Street Milwaukee, WI 53202‐5207

Fund Summaries	1
State Street Income Fund	1
State Street U.S. Core Equity Fund	8
Additional Information About Investment Objectives, Principal Strategies and Risks	14
State Street Income Fund	14
State Street U.S. Core Equity Fund	15
Additional Information About Non-Principal Investment Strategies and Risks	26
Portfolio Holdings Disclosure	27
Management and Organization	28
Shareholder Information	30
Financial Highlights	35