NORTHERN INSTITUTIONAL FUNDS U.S. Government Portfolio

INVESTMENT OBJECTIVE

The Portfolio seeks to maximize current income to the extent consistent with the preservation of capital and maintenance of liquidity by investing exclusively in high quality money market instruments.

FEES AND EXPENSES OF THE PORTFOLIO

This table describes the fees and expenses that you may pay if you buy, hold and sell Shares of the Portfolio. You may be required to pay commissions and/or other forms of compensation to a financial intermediary for transactions in Shares, which are not reflected in the tables or the examples below.

EXAMPLE

The following Example is intended to help you compare the cost of investing in Shares of the Portfolio with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

PRINCIPAL INVESTMENT STRATEGIES

The Portfolio seeks to achieve its objective by investing, under normal circumstances, substantially all (and at least 99.5%) of its total assets in cash, securities issued or guaranteed as to principal or interest by the U.S. government or by a person controlled or supervised by and acting as an instrumentality of the U.S. government pursuant to authority granted by the Congress of the United States or any certificate of deposit of any of the foregoing, and repurchase agreements that are fully collateralized by cash or such securities. The Portfolio, under normal circumstances, will invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in U.S. government securities and repurchase agreements collateralized solely by U.S. government securities.

The Portfolio operates as a “government money market fund” under Rule 2a-7 of the Investment Company Act of 1940, as amended. As a “government money market fund” under Rule 2a-7, the Portfolio (1) is permitted to use the amortized cost method of valuation to seek to maintain a stable net asset value (“NAV”) of $1.00 share price, and (2) is not required to impose a liquidity fee on Portfolio redemptions that might apply to other types of money market funds. The Portfolio may invest in shares of other government money market funds.

The Securities and Exchange Commission (“SEC”) imposes strict requirements on the investment quality, maturity, diversification and liquidity of the Portfolio’s investments. Accordingly, the Portfolio invests in U.S. dollar-denominated securities with a remaining maturity of no more than 397 days (with certain exceptions permitted by applicable regulations).

The Portfolio maintains a dollar-weighted average portfolio maturity of no more than 60 calendar days, and a dollar-weighted average portfolio maturity as determined without exceptions regarding certain interest rate adjustments under Rule 2a-7 of no more than 120 calendar days. The Portfolio will limit its investments to “eligible securities,” as defined by applicable regulations, at the time of acquisition (e.g., government securities, shares of other money market funds, and securities that present minimal credit risks as determined by NTI, pursuant to guidelines approved by the Portfolio’s Board of Trustees). The Portfolio may invest in variable and floating rate instruments. The Portfolio’s investment adviser may consider, among other things, credit, interest rate and prepayment risks as well as general market conditions when deciding whether to buy or sell investments for the Portfolio. The Portfolio will generally hold a portion of its assets in cash to accommodate anticipated redemptions.

PRINCIPAL RISKS

As with any investment, you could lose all or part of your investment in the Portfolio, and the Portfolio’s performance could trail that of other investments. The Portfolio is subject to certain risks, including the principal risks noted below, any of which may adversely affect the Portfolio’s NAV, yield, total return and ability to meet its investment objective. Each risk noted below is considered a principal risk of investing in the Portfolio, regardless of the order in which it appears. The significance of each risk factor below may change over time and you should review each risk factor carefully.

STABLE NAV RISK is the risk that the Portfolio will not be able to maintain a NAV per share of $1.00 at all times. A significant enough market disruption or drop in market prices of securities held by the Portfolio, especially at a time when the Portfolio needs to sell securities to meet shareholder redemption requests, could cause the value of the Portfolio’s shares to decrease to a price less than $1.00 per share. If the Portfolio fails to maintain a stable NAV (or if there is a perceived threat of such a failure) the Portfolio could be subject to increased redemption activity, which could adversely affect its NAV.

INTEREST RATE RISK is the risk that during periods of rising interest rates, the market value of a Portfolio’s securities will tend to be lower than prevailing market rates and in periods of falling interest rates, the market value of the Portfolio’s securities will tend to be higher. A Portfolio’s yield will vary as short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. In general, securities with longer maturities or durations are more sensitive to interest rate changes. A general rise in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions for the Portfolio. During periods when inflation rates are high or rising, or during periods of low interest rates, the Portfolio may be subject to a greater risk of rising interest rates. Changing interest rates may have unpredictable effects on the markets and the Portfolio’s investment, may result in heightened market volatility, may impact the liquidity of fixed-income securities and of the Portfolio, and may detract from Portfolio performance.

CREDIT (OR DEFAULT) RISK is the risk that the inability or unwillingness of an issuer or guarantor of a fixed-income security, or a counterparty to a repurchase or other transaction, to meet its principal or interest payments or other financial obligations will adversely affect the value of the Portfolio’s investments and its returns. Changes in an issuer’s financial strength, the market’s perception of an issuer’s creditworthiness, or in the credit rating of the issuer or the security may also affect the value of the Portfolio’s investment in that issuer.

DEBT EXTENSION RISK is the risk that when interest rates rise an issuer will exercise its right to pay principal on certain debt securities held by the Portfolio later than expected. This will cause the value of the security to decrease and the Portfolio may lose opportunities to invest in higher yielding securities.

PREPAYMENT (OR CALL) RISK is the risk that an issuer could exercise its right to pay principal on callable debt securities held by the Portfolio earlier than expected. Issuers may be more likely to prepay their securities if interest rates fall. If this happens, the Portfolio will not benefit from the rise in the market price of the securities that normally accompanies a decline in interest rates, and will be forced to reinvest prepayment proceeds in lower yielding securities, which may reduce the Portfolio’s returns. The Portfolio may also lose any premium it paid to purchase the securities.

VARIABLE OR FLOATING RATE INSTRUMENTS RISK is the risk that securities with variable or floating rates can be less sensitive to interest rate changes than securities with fixed interest rates, but may decline in value and negatively impact the Portfolio, particularly if changes in prevailing interest rates are more frequent or sudden than the rate changes for the variable or floating rate securities, which only occur periodically. Although variable and floating rate securities are less sensitive to interest rate risk than fixed-rate securities, they are subject to greater liquidity risk, which could impede their value.

INCOME RISK is the risk that the Portfolio’s ability to distribute income to shareholders depends on the yield available from the Portfolio’s investments. Falling interest rates will cause the Portfolio’s income to decline. Income risk is generally higher for short-term debt securities.

U.S. GOVERNMENT SECURITIES RISK is the risk that the U.S. government will not provide financial support to its agencies, instrumentalities or sponsored enterprises if it is not obligated to do so by law. Certain U.S. government securities purchased by the Portfolio are neither issued nor guaranteed by the U.S. Treasury and, therefore, may not be backed by the full faith and credit of the United States. The maximum potential liability of the issuers of some U.S. government securities may greatly exceed their current resources, including any legal right to support from the U.S. Treasury. It is possible that the issuers of such securities will not have the funds to meet their payment obligations in the future. U.S. government securities include zero coupon securities, which tend to be subject to greater market risk than interest-paying securities of similar maturities.

REPURCHASE AGREEMENTS RISK is the risk that the counterparty may default on its obligation to repurchase the underlying instruments collateralizing the repurchase agreement, which may cause the Portfolio to lose money.

INVESTMENT COMPANY RISK is the risk that the Portfolio will be subject to the risks associated with investments in registered investment companies (“Underlying Funds”), such as the possibility that the value of the securities or instruments held by the Underlying Funds could decrease. Investments in

Underlying Funds may involve duplication of management fees and certain other expenses, as the Portfolio indirectly bears its proportionate share of any expenses paid by the Underlying Funds in which it invests.

MARKET RISK is the risk that the value of the Portfolio’s investments may increase or decrease in response to expected, real or perceived economic, political or financial events in the U.S. or global markets. The frequency and magnitude of such changes in value cannot be predicted. Certain securities and other investments held by the Portfolio may experience increased volatility, illiquidity, or other potentially adverse effects in response to changing market conditions, inflation, changes in interest rates, lack of liquidity in the bond or equity markets or volatility in the equity markets. Market disruptions caused by local or regional events such as financial institution failures, war, acts of terrorism, the spread of infectious illness (including epidemics and pandemics) or other public health issues, recessions or other events or adverse investor sentiment or other political, regulatory, economic and social developments, and developments that impact specific economic sectors, industries or segments of the market. During periods of market disruption or other abnormal market conditions, the Portfolio’s exposure to risks described elsewhere in this summary will likely increase.

CASH POSITIONS RISK is the risk that maintaining cash positions may negatively affect the Portfolio’s performance and subject the Portfolio to additional risks, such as increased counterparty risk exposure to the custodian bank.

MANAGEMENT RISK is the risk that a strategy used by the Portfolio’s investment adviser may fail to produce the intended results or that imperfections, errors or limitations in the tools and data used by the investment adviser may cause unintended results.

LARGE SHAREHOLDER RISK is the risk that the Portfolio may experience adverse effects when certain large shareholders, including funds or accounts over which the Portfolio’s investment adviser or an affiliate of the investment adviser has investment discretion, purchase or redeem large amounts of shares of the Portfolio. Such large shareholder redemptions, which may occur rapidly and unexpectedly, may cause the Portfolio to sell its securities at times it would not otherwise do so, which may negatively impact its liquidity and/or NAV. Such sales may also accelerate the realization of taxable income to shareholders if these sales result in gains, and may also increase transaction costs. In addition, large redemptions could lead to an increase in the Portfolio’s expense ratio due to expenses being allocated over a smaller asset base. Large purchases of the Portfolio’s shares may also adversely affect the Portfolio’s performance to the extent that the Portfolio is delayed in investing new cash or otherwise maintains a larger cash position than it ordinarily would.

You could lose money by investing in the Portfolio. Although the Portfolio seeks to preserve the value of your investment at $1.00 per share, the Portfolio cannot guarantee it will do so.

An investment in the Portfolio is not a bank account and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.

The Portfolio’s sponsor is not required to reimburse the Portfolio for losses, and you should not expect that the sponsor will provide financial support to the Portfolio at any time, including during periods of market stress.

PORTFOLIO PERFORMANCE

The bar chart and table that follow provide an indication of the risks of investing in the Portfolio by showing changes in the performance of the Portfolio’s Shares from year to year.

The Portfolio’s past performance is not necessarily an indication of how the Portfolio will perform in the future.

Updated performance information for the Portfolio is available and may be obtained on the Portfolio’s website at www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-institutional or by calling 800-637-1380.

CALENDAR YEAR TOTAL RETURNS (SHARES)*

* For the periods shown in the bar chart above:

AVERAGE ANNUAL TOTAL RETURNS

(For the periods ended December 31, 2023)

The 7-day yield for Shares of the Portfolio as of December 31, 2023: 5.17%. For the current 7-day yield call 800-637-1380 or visit www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-institutional.

MANAGEMENT

INVESTMENT ADVISER. NTI, an indirect subsidiary of Northern Trust Corporation, serves as the investment adviser of the Portfolio. The Northern Trust Company, an affiliate of NTI, serves as transfer agent, custodian and sub-administrator to the Portfolio.

PURCHASE AND SALE OF PORTFOLIO SHARES

You may purchase Shares of the Portfolio through an account directly with Northern Institutional Funds (the “Trust”) generally with a minimum initial investment of $5 million in one or more of the Trust’s portfolios. There is no minimum for subsequent investments. The Trust reserves the right to waive the minimum investment requirement in connection with the purchase of Portfolio Shares.

You may also purchase Shares of the Portfolio through an institutional account at Northern Trust (or an affiliate) or an authorized intermediary with no minimum initial or subsequent investment minimum.

If you purchase, sell (redeem) or exchange Shares through an authorized intermediary, you may be required to pay a commission and/or other forms of compensation to the intermediary. In addition, an authorized intermediary may impose different investment minimums than those set forth above. The Portfolio is not responsible for any investment minimums imposed by authorized intermediaries or for notifying shareholders of any changes to them.

On any business day, you may sell (redeem) or exchange Portfolio shares through your institutional account by contacting your Northern Trust account representative or authorized intermediary. If you purchase Portfolio shares directly from the Trust, you may sell (redeem) or exchange your shares in one of the following ways:

TAX INFORMATION

The Portfolio’s distributions are generally taxable to you as ordinary income, unless you are investing through a tax-exempt or tax-advantaged arrangement, such as a 401(k) plan or an individual retirement account. Distributions may be taxable upon withdrawal from tax-advantaged accounts.

PAYMENTS TO BROKERS-DEALERS AND OTHER FINANCIAL INTERMEDIARIES

If you purchase the Portfolio through a broker-dealer or other financial intermediary (such as a bank), the Portfolio and its related companies may pay the intermediary for the sale of Portfolio shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Portfolio over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.