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TREASURY PORTFOLIO—SIEBERT WILLIAMS SHANK SHARES

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TREASURY PORTFOLIO—SIEBERT WILLIAMS SHANK SHARES

PORTFOLIO SUMMARY

TREASURY 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 its net assets, under normal market conditions, exclusively in U.S. Treasury securities and related repurchase agreements and other securities that limit their investments to, or are backed by, U.S. Treasury securities.

FEES AND EXPENSES OF THE PORTFOLIO

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Portfolio. You may be required to pay commissions and/or other forms of compensation to a financial intermediary for transactions in Siebert Williams Shank 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 through December 31, 2022). 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, its total assets exclusively in:

The Portfolio, under normal circumstances, will invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in Treasury Obligations and repurchase agreements collateralized solely by Treasury Obligations.

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 and/or a redemption gate on Portfolio redemptions that might apply to other types of money market funds should certain triggering events specified in Rule 2a-7 occur.

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’s investments must have a remaining maturity of no more than 397 days and must be high quality. 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.

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TREASURY PORTFOLIO

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, trading price, 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 Portfolio’s yield (and the market value of its securities) will tend to be lower than prevailing market rates; in periods of falling interest rates, the Portfolio’s yield (and the market value of its securities) will tend to be higher. Securities with longer maturities tend to be more sensitive to changes in interest rates, causing them to be more volatile than securities with shorter maturities. Securities with shorter maturities tend to provide lower returns and be less volatile than securities with longer maturities. If interest rates rise, the Portfolio’s yield may not increase proportionately, and the maturities of income securities that have the ability to be prepaid or called by the issuer may be extended. Interest rates in the U.S. are currently at historically low levels. Changing interest rates may have unpredictable effects on the markets and the Portfolio’s investments. A low or negative interest rate environment could cause the Portfolio’s earnings to fall below the Portfolio’s expense ratio, resulting in a low or negative yield and decline in the Portfolio’s share price. 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. Fluctuations in interest rates may also affect the liquidity of fixed income securities and instruments held by the Portfolio.

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. The credit quality of a debt security or of the issuer of a debt security held by the Portfolio could deteriorate rapidly, which may impair the Portfolio’s liquidity or cause a deterioration in the Portfolio’s NAV. The Portfolio could also be delayed or hindered in its enforcement of rights against an issuer, guarantor or counterparty.

DEBT EXTENSION RISK is the risk that an issuer will exercise its right to pay principal on an obligation held by the Portfolio (such as an asset-backed security) later than expected. This may happen during a period of rising interest rates. Under these circumstances, the value of the obligation will decrease and the Portfolio will suffer from the inability to invest in higher yielding 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, credit risk and default 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.

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, volatility in the equity markets, market disruptions caused by local or regional events such as 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. These risks may be magnified if certain events or developments adversely interrupt the global supply chain; in these and other circumstances, such risks

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TREASURY PORTFOLIO

might affect companies worldwide due to increasingly interconnected global economies and financial markets.

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.

CYBERSECURITY RISK is the risk of an unauthorized breach and access to Portfolio assets, Portfolio or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Portfolio, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Portfolio investors from purchasing, redeeming or exchanging shares or receiving distributions. The Portfolio and its investment adviser have limited ability to prevent or mitigate cybersecurity incidents affecting third party service providers, and such third-party service providers may have limited indemnification obligations to the Portfolio or its investment adviser. Successful cyber-attacks or other cyber-failures or events affecting the Portfolio or its service providers may adversely impact and cause financial losses to the Portfolio or its shareholders. Issuers of securities in which the Portfolio invests are also subject to cybersecurity risks, and the value of these securities could decline if the issuers experience cyber-attacks or other cyber-failures.

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 deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, Siebert Williams Shank & Co., LLC or its affiliates, or The Northern Trust Company, its affiliates, subsidiaries or any other bank. The Portfolio’s sponsor has no legal obligation to provide financial support to the Portfolio, and you should not expect that the sponsor will provide financial support to the Portfolio at any time.

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 from year to year. Performance shown is that of Shares Class, another class of shares of the Portfolio that is offered in a separate prospectus. Siebert Williams Shank Shares would have substantially similar annual returns because the Shares Class is invested in the same portfolio of securities and the annual returns would differ only to the extent that the classes do not have the same expenses.

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 northerntrust.com/institutional or by calling 800-637-1380.

CALENDAR YEAR TOTAL RETURNS (SHARES)*

* Year to date total return for the nine months ended September 30, 2021 is 0.01%. For the periods shown in the bar chart above:

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AVERAGE ANNUAL TOTAL RETURNS

(For the periods ended December 31, 2020)

The 7-day yield for Shares Class shares of the Portfolio as of December 31, 2020: 0.01%. For the current 7-day yield call 800-637-1380 or visit northerntrust.com/institutional.

MANAGEMENT

INVESTMENT ADVISER. Northern Trust Investments, Inc. (“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 Siebert Williams Shank Shares of the Portfolio through an account directly with the Northern Institutional Funds, through your institutional account at Northern Trust (or an affiliate) or through an authorized intermediary, generally with no minimum initial investment. The Siebert Williams Shank shares class of the Portfolio is not offered for purchase through Northern Trust custody sweep.

On any business day, you may sell (redeem) or exchange Siebert Williams Shank shares of the Portfolio through your institutional account by contacting your Northern Trust account representative or authorized intermediary. If you purchase Siebert Williams Shank Shares of the Portfolio 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, capital gains, or a combination of the two, unless you are investing through a tax-exempt or tax-deferred arrangement, such as a 401(k) plan or an individual retirement account. Distributions may be taxable upon withdrawal from tax-deferred 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.

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INVESTMENT ADVISER

This Prospectus describes one money market portfolio (the “Portfolio”) which is currently offered by Northern Institutional Funds (the “Trust”).

Northern Trust Investments, Inc. (“NTI” or the “Investment Adviser”), an indirect subsidiary of Northern Trust Corporation, serves as the Investment Adviser of the Portfolio and is responsible for its overall administration. NTI is located at 50 South LaSalle Street, Chicago, Illinois 60603.

NTI is an Illinois State Banking Corporation and an investment adviser registered under the Investment Advisers Act of 1940, as amended. It primarily manages assets for institutional and individual separately managed accounts, investment companies and bank common and collective funds.  

Northern Trust Corporation is regulated by the Board of Governors of the Federal Reserve System as a financial holding company under the U.S. Bank Holding Company Act of 1956, as amended. Unless otherwise indicated, NTI and The Northern Trust Company (“TNTC”) are referred to collectively in this Prospectus as “Northern Trust.”

As of September 30, 2021, Northern Trust Corporation, through its affiliates, had assets under custody of $12.25 trillion, and assets under investment management of $1.53 trillion.

Under the Management Agreements with the Trust, the Investment Adviser, subject to the general supervision of the Trust’s Board of Trustees, is responsible for making investment decisions for the Portfolio and for placing purchase and sale orders for portfolio securities, as well as for providing administration services to the Portfolio.

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MANAGEMENT FEES

As compensation for advisory services and administration services and the assumption of related expenses, NTI is entitled to a management fee, computed daily and payable monthly, at annual rates set forth in the table below (expressed as a percentage of the Portfolio’s average daily net assets). The table also reflects the management fees paid by the Portfolio for the fiscal year ended November 30, 2020 (expressed as a percentage of the Portfolio’s average daily net assets).

NTI has contractually agreed to reimburse a portion of the operating expenses of the Portfolio (other than certain fees and expenses shown in the table under the caption “Fees and Expenses of the Portfolio” in the Portfolio’s Portfolio Summary) so that “Total Annual Portfolio Operating Expenses After Expense Reimbursement” do not exceed the amount shown in the footnote to the table under the caption “Fees and Expenses of the Portfolio” in the Portfolio Summary. The “Total Annual Portfolio Operating Expenses After Expense Reimbursement” for the Portfolio may be higher than the contractual limitation for the Portfolio as a result of certain excepted expenses that are not reimbursed. The contractual expense reimbursement arrangement is expected to continue until at least December 31, 2022. The contractual expense reimbursement arrangement will continue automatically thereafter for periods of one year (each such one-year period, a “Renewal Year”). The arrangement may be terminated, as to any succeeding Renewal Year, by NTI or the Portfolio upon 60 days’ written notice prior to the end of the current Renewal Year. The Board of Trustees may terminate the arrangement at any time if it determines that it is in the best interest of the Portfolio and its shareholders.

NTI may reimburse additional expenses or waive all or a portion of the management fees of the Portfolio from time to time, including to avoid a negative yield. Any such additional expense reimbursement or fee waiver would be voluntary and could be implemented, increased or decreased, or discontinued at any time. There is no guarantee that the Portfolio will be able to avoid a negative yield.

A discussion regarding the Board of Trustees’ basis for its most recent approval of the Portfolio’s Management Agreement is available in the Portfolio’s semi-annual report to shareholders for the six-month period ended May 31, 2021.

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OTHER PORTFOLIO SERVICES

TNTC serves as Transfer Agent and Custodian for the Portfolio. The Transfer Agent performs various shareholder servicing functions, and any shareholder inquiries should be directed to it. TNTC also performs certain administrative services for the Portfolio pursuant to a sub-administration agreement with NTI. NTI pays TNTC for its sub-administration services out of its management fees, which do not represent additional expenses to the Portfolio.

TNTC, as Transfer Agent, is entitled to transfer agent fees at an annual rate of 0.015% of the average daily net assets of the Portfolio. TNTC, as Custodian, receives an amount based on a pre-determined schedule of charges approved by the Trust’s Board of Trustees.

TNTC, NTI and other Northern Trust affiliates may provide other services to the Portfolio and receive compensation for such services if consistent with the Investment Company Act of 1940, as amended (the “1940 Act”) and the rules, exemptive orders and no-action letters issued by the SEC thereunder. Unless required, investors in the Portfolio may or may not receive specific notice of such additional services and fees.

Shares of the Trust are distributed by Northern Funds Distributors, LLC (“NFD”), Three Canal Plaza, Suite 100, Portland, Maine, 04101. NFD is not affiliated with TNTC, NTI or any other Northern Trust affiliate.

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PURCHASING AND SELLING SIEBERT WILLIAMS SHANK SHARES

THE TRUST OFFERS ONE MONEY MARKET PORTFOLIO TO INSTITUTIONAL INVESTORS IN THIS PROSPECTUS.

The descriptions in the Portfolio Summary may help you decide whether the Portfolio fits your investment needs. Keep in mind, however, that no guarantee can be made that the Portfolio will meet its investment objective and the Portfolio should be relied upon as a complete investment program.

INVESTORS

Institutional investors (“Institutions”), acting on their own behalf or on behalf of customers and other beneficial owners (“Customers”), may invest in the Siebert Williams Shank Shares of the Portfolio.

Institutions are:

Please note that the fee and expense information shown under “Fees and Expenses of the Portfolio” in the Portfolio Summary beginning on page 3 does not reflect any charges (such as allocation or account maintenance fees) that may be imposed by TNTC, its affiliates, Siebert Williams Shank & Co., LLC (“SWS”) or other financial intermediaries on their clients. SWS is a minority- and women-owned independent, non-bank financial services firm. SWS is not affiliated with Northern Trust. (For more information, please see “Account Policies and Other Information—Financial Intermediaries” on page 16.)

SHARE CLASSES

The Portfolio is authorized to offer four classes of shares: Shares, Service Shares, Premier Shares and Siebert Williams Shank Shares. Siebert Williams Shank Shares bear their pro rata portion of all operating expenses paid by the Portfolio, except for transfer agent fees.

PURCHASING SIEBERT WILLIAMS SHANK SHARES

You may purchase Siebert Williams Shank Shares of the Portfolio through an account directly with the Northern Institutional Funds, through your institutional account at Northern Trust (or an affiliate) or through an authorized intermediary, generally with no minimum initial investment.

The Siebert Williams Shank Shares class of the Portfolio is not offered for purchase through Northern Trust custody sweep.

OPENING AN ACCOUNT

THROUGH AN INSTITUTIONAL ACCOUNT. If you are opening an institutional account at Northern Trust, a Northern Trust representative can assist you with all phases of your investment. To purchase shares through your account, contact your Northern Trust representative for further information.

THROUGH AN AUTHORIZED INTERMEDIARY. The Trust has authorized SWS and certain Institutions acting as financial intermediaries (including banks, trust companies, brokers and investment advisers) to accept purchase orders from their customers on behalf of the Portfolio. See “Account Policies and Other Information—Financial Intermediaries” beginning on page 16 for additional information regarding purchases of Siebert Williams Shank shares of the Portfolio through authorized intermediaries.

DIRECTLY FROM THE TRUST. An Institution may open a shareholder account and purchase shares directly from the Trust as described above under “Purchasing Siebert Williams Shank Shares.”

For your convenience, there are a number of ways to invest directly in the Portfolio:

BY MAIL

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Northern Institutional Funds

P.O. Box 75986

Chicago, Illinois 60675-5986

All checks must be payable in U.S. dollars and drawn on a bank located in the United States. Cash and third party checks are not acceptable.

Northern Institutional Funds

c/o The Northern Trust Company

333 South Wabash Ave

Chicago, Illinois 60604

BY TELEPHONE

TO OPEN A NEW ACCOUNT PLEASE PROVIDE:

TO ADD TO AN EXISTING ACCOUNT; PLEASE PROVIDE:

BY WIRE OR AUTOMATED CLEARING HOUSE (“ACH”) TRANSFER

TO OPEN A NEW ACCOUNT:

TO ADD TO AN EXISTING ACCOUNT:

The Northern Trust Company

Chicago, Illinois

ABA Routing No. 0710-00152

(Reference 10-Digit Portfolio account number, with no spaces

(e.g., ##########))

(Reference Shareholder’s Name)

SELLING SIEBERT WILLIAMS SHANK SHARES

THROUGH AN INSTITUTIONAL ACCOUNT. Institutions may sell (redeem) shares through their institutional account by contacting their Northern Trust account representative.

THROUGH AN AUTHORIZED INTERMEDIARY. Institutions that purchase Siebert Williams Shank Shares from an authorized intermediary may sell (redeem) their Siebert Williams Shank Shares by contacting their financial intermediary. See “Account Policies and Other Information—Financial Intermediaries” beginning on page 16 for additional information regarding sales (redemptions) of Siebert Williams Shank Shares through authorized intermediaries.

DIRECTLY THROUGH THE TRUST. Institutions that purchase Siebert Williams Shank Shares directly from the Trust may redeem their Siebert Williams Shank Shares through the Transfer Agent in one of the following ways:

BY MAIL

SEND A WRITTEN REQUEST TO:

Northern Institutional Funds

P.O. Box 75986

Chicago, Illinois 60675-5986

THE LETTER OF INSTRUCTION MUST INCLUDE:

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BY TELEPHONE

BY WIRE

If you authorize wire redemptions on your New Account Application, you can redeem shares and have the proceeds sent by federal wire transfer to a previously designated bank account.

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ACCOUNT POLICIES AND OTHER INFORMATION

PURCHASE AND REDEMPTION MINIMUMS. There is generally no minimum initial investment for Siebert Williams Shank Shares of the Portfolio when purchasing shares through an authorized intermediary. A $10,000 minimum applies for redemptions by wire. The Trust reserves the right to waive redemption minimums and to determine the manner in which a minimum is satisfied.

CALCULATING SHARE PRICE. The Trust issues and redeems shares at NAV. The NAV for each class of shares of the Portfolio is calculated by dividing the value of the Portfolio’s net assets attributed to that class by the number of the Portfolio’s outstanding shares of the class. The NAV for the Portfolio is calculated on each Business Day as of 4:00 p.m. Central time. Portfolio shares may be priced on days when the New York Stock Exchange (the “Exchange”) is closed if the Securities Industry and Financial Markets Association (“SIFMA”) recommends that the bond markets remain open for all or part of the day or on days when the Federal Reserve Bank of New York (the “New York Fed”) is open. The NAV used in determining the price of your shares is the one calculated after your purchase, exchange or redemption order is received in good order as described on page 16.

The Portfolio seeks to maintain a stable NAV of $1.00 per share by valuing the obligations held by it at amortized cost in accordance with SEC regulations. Amortized cost will normally approximate fair value.

TIMING OF PURCHASE REQUESTS. Purchase requests received in good order and accepted by the Transfer Agent or other authorized intermediary on any Business Day by 4:00 p.m. Central time, will be executed the day they are received by either the Transfer Agent or other authorized intermediary, at that day’s closing share price for the Portfolio, provided that one of the following occurs:

Purchase requests received in good order by the Transfer Agent or other authorized intermediary on a non-Business Day or after the deadlines described above on a Business Day will be executed on the next Business Day, at that day’s closing share price for the Portfolio, provided that payment is made as noted above.

IN-KIND PURCHASES AND REDEMPTIONS. The Trust reserves the right to accept payment for shares in the form of securities that are permissible investments for the Portfolio. The Trust also reserves the right to pay redemptions by a distribution “in-kind” of securities (instead of cash) from the Portfolio. See the SAI for further information about the terms of these purchases and redemptions.

MISCELLANEOUS PURCHASE INFORMATION.

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TIMING OF REDEMPTION AND EXCHANGE REQUESTS.

Redemption and exchange requests received in good order by the Transfer Agent or other authorized intermediary on any Business Day by 4:00 p.m. Central time, will be executed on the same day at that day’s closing share price for the Portfolio.

Redemption and exchange requests received in good order by the Transfer Agent or other authorized intermediary on a non-Business Day or after the deadline described above on a Business Day will be executed the next Business Day at that day’s closing share price for the Portfolio.

PAYMENT OF REDEMPTION PROCEEDS. If your account is held directly with the Portfolio, it is expected that under normal circumstances the Portfolio will typically pay out redemption proceeds to shareholders by the next Business Day following a receipt of a redemption request in good order.

If your account is held through an intermediary, the length of time to pay redemption proceeds typically depends, in part, on the terms of the agreement in place between the intermediary and the Portfolio. For redemption proceeds that are paid either directly to you from the Portfolio or to your intermediary for transmittal to you, it is expected that under normal circumstances payments will typically be made by wire, by ACH or by issuing check by the next Business Day following receipt of a redemption request in good order from the intermediary by the Portfolio. Intermediaries are responsible for timely transmittal of redemption requests by their customers to the Portfolio’s transfer agent. Redemption requests that are processed through investment professionals that utilize the National Securities Clearing Corporation will generally settle one to three Business Days following receipt of a redemption request in good order.

However, if you have recently purchased shares with a check or through an electronic transaction, payment may be delayed as discussed below under “Miscellaneous Redemption Information.”

It is expected that payment of redemption proceeds will normally be made from uninvested cash or short-term investments, proceeds from the sale of portfolio securities, or borrowing through the Trust’s committed, unsecured credit facility (see “Credit Facility and Borrowing,” on page 22). It is possible that stressed market conditions or large shareholder redemptions may result in the need for utilization of the Portfolio’s ability to redeem in-kind in order to meet shareholder redemption requests. The Portfolio reserves the right to pay all or part of your redemption proceeds in readily marketable securities instead of cash (redemption in-kind). Redemption in-kind proceeds will typically be made by delivering the selected securities to the redeeming shareholder within seven days after the receipt of the redemption request in good order by the Portfolio.

Large unexpected redemptions to the Portfolio can disrupt portfolio management and increase trading costs by causing the Portfolio to liquidate a substantial portion of its assets in a short period of time. When experiencing a redemption by a large shareholder, the Portfolio may delay payment of the redemption request for up to seven days to provide NTI with time to determine if the Portfolio can redeem the request-in-kind or to consider other alternatives to lessen the harm to remaining shareholders. Under certain circumstances, however, the Portfolio may be unable to delay a redemption request, which could result in the automatic processing of a large redemption that is detrimental to the Portfolio and its remaining shareholders.

The Portfolio does not intend to avail itself of the ability to impose liquidity fees and/or redemption gates. However, the Board of Trustees reserves the right, with notice to shareholders, to change this policy, thereby permitting the Portfolio to impose such fees and gates in the future.

MISCELLANEOUS REDEMPTION INFORMATION. All redemption proceeds will be sent by check unless the Transfer Agent is directed otherwise. Redemption proceeds also may be wired. Redemptions are subject to the following restrictions:

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EXCHANGE PRIVILEGES. Institutions and their Customers (to the extent permitted by their account agreements) may exchange shares of the Portfolio for shares of another portfolio of the Trust subject to that portfolio’s eligibility requirements and if the registration of both accounts is identical. Both accounts must have the same owner’s name and title, if applicable. A $1,000 minimum applies to exchanges. An exchange is a redemption of shares of the Portfolio and the purchase of shares of another investment portfolio in the Trust. If the shares redeemed are held in a taxable account, an exchange is considered a taxable event and may result in a gain or loss. The Trust reserves the right to waive or modify minimum investment requirements in connection with exchanges.

The Trust reserves the right to change or discontinue the exchange privilege at any time upon 60 days’ written notice to shareholders and to reject any exchange request. Exchanges are only available in states where an exchange can legally be made. Before making an exchange, you should read the Prospectus for the shares you are acquiring.

EXCESSIVE TRADING IN PORTFOLIO SHARES. The Board of Trustees of the Trust has not adopted, on behalf of the Portfolio, policies and procedures with respect to frequent purchases and redemptions of Portfolio shares in light of the nature and high quality of the Portfolio’s investments. The Portfolio reserves the right to refuse a purchase order if management of the Portfolio determines that the purchase may not be in the best interests of the Portfolio.

TELEPHONE TRANSACTIONS. All calls may be recorded or monitored. The Transfer Agent has adopted procedures in an effort to establish reasonable safeguards against fraudulent telephone transactions. If reasonable measures are taken to verify that telephone instructions are genuine, the Trust and its service providers will not be responsible for any loss resulting from fraudulent or unauthorized instructions received over the telephone. In these circumstances, shareholders will bear the risk of loss. During periods of unusual market activity, you may have trouble placing a request by telephone. In this event, consider sending your request in writing.

The proceeds of redemption orders received by telephone will be sent by check, wire or transfer according to proper instructions. All checks will be made payable to the shareholder of record and mailed only to the shareholder’s address of record.

The Trust reserves the right to refuse a telephone redemption, subject to applicable law.

ADVANCE NOTIFICATION OF LARGE TRANSACTIONS. The Trust requests that an Institution give advance notice to the Transfer Agent by 11:00 a.m. Central time if it intends to place a purchase or redemption order of $5 million or more on a Business Day. For other large purchase or redemption orders

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below $5 million, the Trust requests that an Institution give advance notice to the Transfer Agent as early as possible in the day.

MAKING CHANGES TO YOUR ACCOUNT INFORMATION. You may make changes to wiring instructions only in writing. You may make changes to an address of record or certain other account information in writing or by telephone. Written instructions must be accompanied by acceptable evidence of authority (if applicable). A signature guarantee also may be required from an institution participating in STAMP. Additional requirements may be imposed. In accordance with SEC regulations, the Trust and Transfer Agent may charge a shareholder reasonable costs in locating a shareholder’s current address.

SIGNATURE GUARANTEES. If a signature guarantee is required, it must be from an institution participating in STAMP, or other acceptable evidence of authority (if applicable) must be provided. Additional requirements may be imposed by the Trust. In addition to the situations described in this Prospectus, the Trust may require signature guarantees in other circumstances based on the amount of a redemption request or other factors.

BUSINESS DAY. A “Business Day” is each Monday through Friday that the New York Fed is open for business, except as noted below. The New York Fed is closed on the following national holidays: New Year’s Day, Martin Luther King, Jr. Day, Presidents’ Day, Memorial Day, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving Day and Christmas Day. The Portfolio may also close on days when the New York Fed is open but the Exchange is closed, such as Good Friday.

GOOD ORDER. A purchase, redemption or exchange request is considered to be “in good order” when all necessary information is provided and all required documents are properly completed, signed and delivered, including acceptable evidence of authority (if applicable). Additionally, a purchase order initiating the opening of an account will not be considered to be “in good order” unless the investor has provided all information required by the Trust’s “Customer Identification Program” described below.

CUSTOMER IDENTIFICATION PROGRAM. Federal law requires the Trust to obtain, verify and record identifying information, which may include the name, business street address, taxpayer identification number or other identifying information for each investor who opens or reopens an account with the Trust. Applications without this information, or without an indication that a taxpayer identification number has been applied for, may not be accepted. After acceptance, to the extent permitted by applicable law or the Trust’s customer identification program, the Trust reserves the right to: (a) place limits on account transactions until an investor’s identity is verified; (b) refuse an investment in the Trust; or (c) involuntarily redeem an investor’s shares and close an account in the event that an investor’s identity is not verified. The Trust and its agents will not be responsible for any loss in an investor’s account resulting from an investor’s delay in providing all required identifying information or from closing an account and redeeming an investor’s shares when an investor’s identity is not verified.

EARLY CLOSINGS. The Portfolio reserves the right to advance the time for accepting purchase, redemption or exchange orders for same Business Day credit when the Exchange and/or the bond market close early, trading on the Exchange is restricted, an emergency arises or as otherwise permitted by the SEC. In addition, on any Business Day when SIFMA recommends that the bond markets close early, the Portfolio reserves the right to close at or prior to the SIFMA recommended closing time. If the Portfolio does so, it will cease granting same Business Day credit for purchase and redemption orders received at the Portfolio’s closing time and credit will be given on the next Business Day. In addition, the Board of Trustees of the Trust also may, for any Business Day, decide to change the time as of which the Portfolio’s NAV is calculated in response to new developments such as altered trading hours, or as otherwise permitted by the SEC.

EMERGENCY OR UNUSUAL EVENTS. In the event the Exchange does not open for business because of an emergency or unusual event, the Trust may, but is not required to, open one or more Portfolios for purchase, redemption and exchange transactions if the Federal Reserve wire payment system is open. To learn whether the Portfolio is open for business during an emergency situation or unusual event, please call 800-637-1380 or visit northerntrust.com/institutional.

FINANCIAL INTERMEDIARIES. The Trust has authorized SWS and certain Institutions acting as financial intermediaries (including banks, trust companies, brokers and investment advisers) to accept purchase, redemption and exchange orders from their Customers on behalf of the Portfolio. These authorized intermediaries also may designate other intermediaries to accept such orders, if approved by the Trust. The Portfolio will be deemed to have received an order when the order is accepted by the authorized intermediary, and the order will be priced at the Portfolio’s per share NAV next determined, provided that the authorized intermediary forwards the order (and payment for any purchase order) to the Transfer Agent on behalf of the Trust within agreed-upon time periods. If the order (or payment for any purchase order) is not received by the Transfer Agent within such time periods, the authorized intermediary may be liable for fees and losses and the transaction may be cancelled.

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NTI has entered into an agreement with SWS whereby NTI pays SWS a fee for distribution and other services provided by SWS. The additional compensation and payments will be paid to SWS by NTI or its affiliates and will not represent an additional expense to the Portfolio or its shareholders. Such payments may provide an incentive for SWS to recommend shares of the Portfolio when it might not have done so absent such payments.

In addition, Northern Trust may enter into agreements with financial intermediaries through which Customers own shares of the Siebert Williams Shank Shares class of the Portfolio, pursuant to which Northern Trust pays these financial intermediaries for providing certain services. The payments made by Northern Trust to financial intermediaries will be paid by Northern Trust and will not represent an additional expense to the Portfolio or its shareholders.

Northern Trust also may provide compensation to certain dealers for marketing and distribution in connection with the Northern Institutional Funds.

Northern Trust may also sponsor informational meetings, seminars and other similar programs designed to market the Northern Institutional Funds. The amount of such compensation and payments may be made on a one-time and/ or periodic basis, and may represent all or a portion of the annual fees earned by the Investment Adviser (after adjustments). The additional compensation and payments will be paid by Northern Trust or its affiliates and will not represent an additional expense to the Trust or its shareholders. Such payments may provide incentives for financial intermediaries to make shares of the Portfolio available to their Customers, and may allow the Portfolio greater access to such parties and their Customers than would be the case if no payments were paid.

Customers purchasing shares of the Portfolio through a financial intermediary should read their account agreements with the financial intermediary carefully. A financial intermediary’s requirements may differ from those listed in this Prospectus. A financial intermediary also may impose account charges, such as asset allocation fees, account maintenance fees, and other charges that will reduce the net return on an investment in the Portfolio. If a Customer has agreed with a particular financial intermediary to maintain a minimum balance and the balance falls below this minimum, the Customer may be required to redeem all or a portion of the Customer’s investment in the Portfolio.

Conflict of interest restrictions may apply to the receipt of compensation by a financial intermediary in connection with the investment of fiduciary funds in shares of the Portfolio. Institutions, including banks regulated by the Comptroller of the Currency, Federal Reserve Board and state banking commissions, and investment advisers and other money managers subject to the jurisdiction of the SEC, the Department of Labor or state securities commissions, are urged to consult their legal counsel.

State securities laws regarding the registration of dealers may differ from federal law. As a result, financial intermediaries investing in the Portfolio on behalf of their Customers may be required to register as dealers.

PORTFOLIO HOLDINGS. The Portfolio, or its duly authorized service providers, may publicly disclose holdings of all Northern Institutional Funds in accordance with regulatory requirements, such as periodic portfolio disclosure in filings with the SEC.

The Trust publishes on its website at northerntrust.com/ institutional no later than the fifth business day of each month and for a period of not less than six months, a complete schedule of the Portfolio’s holdings and certain other information regarding portfolio holdings of the Portfolio as of the last business day of the prior month. The Portfolio may publish on the Trust’s website a complete schedule of its portfolio holdings and certain other information regarding portfolio holdings more frequently in accordance with the Trust’s policy. Certain portfolio information concerning the Portfolio will be provided in monthly holdings reports to the SEC on Form N-MFP2. Form N-MFP2 will be made available to the public on the SEC’s EDGAR database immediately upon filing after the end of the month to which the information pertains, and a link to each of the most recent 12 months of filings on Form N-MFP2 will be provided on the Trust’s website. A further description of the Trust’s Policy on Disclosure of Portfolio Holdings is available in the SAI.

SHAREHOLDER COMMUNICATIONS. Shareholders of record will be provided each year with a semiannual report showing portfolio investments and other information as of May 31 and with an annual report containing audited financial statements as of November 30. The reports will be made available on the Portfolio’s website at https://www.northerntrust.com/united-states/what-we-do/investment-management/northern- funds/funds-and-performance-institutional/literature. Unless you have elected to receive the reports in paper, you will be notified by mail each time a report is posted and provided a website link to access the report. You may elect to receive future reports in paper free of charge. If you invest through a financial intermediary, you may contact your financial intermediary to continue receiving paper copies of your shareholder reports. If you invest directly with the Trust, you can inform the Trust that you wish to continue receiving paper copies of your shareholder reports by calling the Northern Institutional Funds Center at 800-637-1380 or by sending an e-mail request to

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northern-funds@ntrs.com. Your election to receive reports in paper will apply to all Northern Institutional Funds you hold in your account at the financial intermediary or through an account with the Trust.

If we have received appropriate written consent, we send a single copy of all materials, including, prospectuses, financial reports, proxy statements or information statements and other notices to all shareholders who share the same mailing address, even if more than one person in a household holds shares of the Portfolio.

If you do not want your mailings combined with those of other members of your household, you may opt-out at any time by contacting the Northern Institutional Funds Center by telephone at 800-637-1380 or by mail at Northern Institutional Funds, P.O. Box 75986, Chicago, Illinois 60675-5986. You also may send an e-mail to: northern-funds@ntrs.com. The Portfolio will begin sending individual copies to you within 30 days after receipt of your opt-out notice.

The Trust may reproduce this Prospectus in electronic format that may be available on the Internet. If you have received this Prospectus in electronic format you, or your representative, may contact the Transfer Agent for a free paper copy of this Prospectus by writing to the Northern Institutional Funds Center at P.O. Box 75986, Chicago, Illinois 60675-5986, calling 800-637-1380 or by sending an e-mail to: northern-funds@ntrs.com.

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DISTRIBUTIONS AND TAX CONSIDERATIONS

DISTRIBUTIONS

Dividends from net income are declared daily and paid monthly by the Portfolio to its shareholders. Net income includes the interest accrued on the Portfolio’s assets less estimated expenses. The Portfolio’s net realized short-term capital gains, if any, are distributed at least annually. The Portfolio does not expect to realize net long-term capital gains.

Dividends are paid as soon as practicable following the end of each month, except in the case of a total redemption of shares in an account that is not subject to a standing order for the purchase of additional shares of the same class. In that event, dividends will be paid promptly along with the redemption proceeds.

All distributions are reinvested automatically (without any sales charge) in additional shares of the same class of the Portfolio, unless you elect to receive distributions in cash by notifying the Transfer Agent in writing. You may make arrangements to credit these distributions to your account with Northern Trust, its affiliates or financial intermediaries.

There are no fees or sales charges on reinvestments.

The Portfolio generally will be invested in debt instruments and not in shares of stock on which dividend income will be received. As a result, the Portfolio does not expect to pay dividends that are eligible for the reduced tax rate on corporate dividends or that will qualify for the dividends-received deduction for corporations.

IRAS AND OTHER TAX-QUALIFIED PLANS. One major exception to the preceding tax principles is that distributions on shares held in an IRA (or other tax-qualified plan) will not be currently taxable unless shares are acquired with borrowed funds.

REDEMPTIONS. Redemptions are treated as sales for tax purposes and generally are taxable events for shareholders that are subject to tax. In general, if Portfolio shares are sold, a shareholder will recognize gain or loss equal to the difference between the amount realized on the sale and the shareholder’s adjusted tax basis in the shares. As long as the Portfolio maintains a constant NAV of $1.00 per share, generally no gain or loss should be recognized upon the sale of shares of the Portfolio.

TAX CONSIDERATIONS

The following is a summary of certain tax considerations that may be relevant to a shareholder in the Portfolio. The discussions of the federal income tax consequences in this Prospectus and the SAI are based on the Internal Revenue Code of 1986, as amended (the “Code”) and the regulations issued

under it, and court decisions and administrative interpretations, as in effect on the date of this Prospectus. Future legislative or administrative changes or court decisions may significantly alter the statements included herein, and any such changes or decisions may be retroactive. Except where otherwise indicated, the discussion relates to shareholders who are individual U.S. citizens or residents and is based on current tax law. You should consult your tax professional for further information regarding federal, state, local and/or foreign tax consequences relevant to your specific situation.

DISTRIBUTIONS. The Portfolio intends to qualify as a regulated investment company for federal income tax purposes and to distribute to shareholders substantially all of its net investment income each year. Except as otherwise noted below, you will generally be subject to federal income tax at ordinary rates on the Portfolio’s distributions to you, regardless of whether they are paid in cash or reinvested in Portfolio shares. U.S. individuals with “modified adjusted gross income” exceeding $200,000 ($250,000 if married and filing jointly) and trusts and estates with income above certain thresholds are subject to the Medicare contribution tax on their “net investment income,” which includes non-exempt interest, dividends and capital gains at a rate of 3.8%. You will be notified annually of the tax status of distributions to you.

BACKUP WITHHOLDING. The Trust will be required in certain cases to withhold and remit to the U.S. Treasury 24% of the dividends and gross sales proceeds paid to any shareholder (i) who had provided either an incorrect tax identification number or no number at all, (ii) who is subject to backup withholding by the IRS for failure to report the receipt of taxable interest or dividend income properly, or (iii) who has failed to certify to the Trust, when required to do so, that he or she is not subject to backup withholding or that he or she is an “exempt recipient.”

U.S. TAX TREATMENT OF FOREIGN SHAREHOLDERS. Portfolio distributions attributable to Portfolio income such as interest will generally be subject to a 30% withholding tax when paid to foreign shareholders. The withholding tax may, however, be reduced (and in some cases eliminated) under an applicable tax treaty between the United States and a shareholder’s country of residence or incorporation, provided that the shareholder furnishes the Portfolio with a properly completed Form W-8BEN or W-8BEN-E, as applicable, to establish entitlement for these treaty benefits. Dividends reported as short-term capital gain dividends or interest-related dividends are not subject to U.S. withholding tax. The exemption may not apply, however, if the recipient’s investment in the Portfolio is connected to a trade or business of the recipient in the United States or if the recipient is present in the United States for 183 days or more in a year and certain other conditions are met.

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However, dividends reported as exempt-interest dividends are generally not subject to U.S. withholding tax. In addition, the Portfolio is required to withhold 30% tax on certain payments to certain foreign entities that do not meet specified information reporting requirements under the Foreign Account Tax Compliance Act.

All foreign investors should consult their own tax professionals regarding the tax consequences in their country of residence of an investment in the Portfolio.

STATE AND LOCAL TAXES. You may also be subject to state and local taxes on income and gain attributable to your ownership of Portfolio shares.

State income taxes may not apply, however, to the portions of the Portfolio’s distributions, if any, that are attributable to interest earned by the Portfolio on U.S. government securities. You should consult your tax professional regarding the tax status of distributions in your state and locality.

CONSULT YOUR TAX PROFESSIONAL. Your investment in the Portfolio could have additional tax consequences. You should consult your tax professional for information regarding all tax consequences applicable to your investments in the Portfolio. More tax information relating to the Portfolio is also provided in the SAI. This short summary is not intended as a substitute for careful tax planning.

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SECURITIES, TECHNIQUES AND RISKS

ADDITIONAL INFORMATION ON INVESTMENT OBJECTIVES, PRINCIPAL INVESTMENT STRATEGIES AND RELATED RISKS, DESCRIPTION OF SECURITIES AND COMMON INVESTMENT TECHNIQUES

The following provides additional information regarding the Portfolio’s investment objective, principal investment strategies and related risks discussed in the Portfolio Summary—Principal Investment Strategies section, as well as information about additional investment strategies and techniques that the Portfolio may employ in pursuing its investment objective. Principal investment strategies and risks for the Portfolio are noted in parenthesis. The Portfolio also may make other types of investments to the extent permitted by applicable law. Additional information about the Portfolio, its investment strategies and risks can also be found in the Portfolio’s SAI.

All investments carry some degree of risk that will affect the value of the Portfolio, its yield and investment performance and the price of its shares. An investment in the Portfolio is not a deposit of any bank and is not insured or guaranteed by the FDIC, any other government agency, SWS or its affiliates, or Northern Trust, its affiliates, subsidiaries or any other bank.

The Portfolio seeks to maintain a stable NAV of $1.00 per share. Although the Portfolio seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Portfolio. This section takes a closer look at some of the Portfolio’s principal investment strategies and related risks.

The Portfolio:

SEC regulations require the Portfolio to limit its dollar-weighted average portfolio maturity to 60 days or less, and its dollar-weighted average portfolio life to 120 days or less. The Portfolio also is required to comply with SEC requirements with respect to the liquidity of the Portfolio’s investments. Specifically, the Portfolio will not acquire any security other than a daily liquid asset unless, immediately following such purchase, at least 10% of its total assets would be invested in daily liquid assets. The Portfolio will not acquire any security other than a weekly liquid asset unless, immediately following such purchase, at least 30% of its total assets would be invested in weekly liquid assets.

For these purposes, daily and weekly liquid assets are calculated as of the end of each business day. Daily liquid assets include cash; direct obligations of the U.S. government; securities that will mature or are subject to a demand feature that is exercisable and payable within one business day; and amounts receivable and due unconditionally within one business day on pending sales of portfolio securities. Weekly liquid assets include: cash; direct obligations of the U.S. government; certain U.S. government agency discount notes without provision for the payment of interest with remaining maturities of 60 days or less; securities that will mature or are subject to a demand feature that is exercisable and payable within five business days; and amounts receivable and due unconditionally within five business days on pending sales of portfolio securities.

In addition, the Portfolio limits its investments to “Eligible securities” as defined by the SEC. Securities in which the Portfolio may invest may not earn as high a level of income as long-term or lower quality securities, which generally have greater market risk and more fluctuation in market value.

Rule 2a-7 requires money market funds to purchase securities that have a remaining maturity of no more than 397 calendar days (unless otherwise permitted under Rule 2a-7), and (i) which have been determined by a money market fund’s board of trustees (or the fund’s investment adviser, if the board of trustees delegates such power to the adviser) to present minimal credit risks to the fund; (ii) are issued by other investment companies that are money market funds; or (iii) are U.S. government securities. NTI considers several factors including the capacity of each security’s issuer or guarantor to meet its financial obligations. In accordance with current SEC regulations, the Portfolio generally will not invest more than: (1) 5% of the value of its total assets at the time of purchase in the securities of any single issuer (and certain affiliates of that issuer); and (2) 10% of the value of its total assets at the time of purchase in the securities subject to demand features or guarantees of any single institution. The Portfolio may, however, invest up to 25% of its total assets in the securities of a single issuer for up to three Business Days. These limitations do not apply to cash, certain repurchase agreements, U.S. government securities or securities of other investment companies that are money market funds. In addition, securities subject to demand features and guarantees are subject to different diversification requirements as described in the SAI.

STABLE NAV RISK. (principal risk for the Portfolio) is the risk that the Portfolio will not be able to maintain a NAV per share of $1.00 at all times. If the Portfolio fails to maintain a stable NAV

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(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. 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.

INVESTMENT OBJECTIVE. The investment objective of the Portfolio may not be changed without shareholder approval. During extraordinary market conditions and interest rate environments, all or any portion of the assets of the Portfolio may be uninvested. Uninvested assets do not generate income. The Portfolio may not achieve its investment objectives during this time.

BORROWINGS AND REVERSE REPURCHASE AGREEMENTS. The Portfolio may borrow money from banks and may enter into reverse repurchase agreements with banks and other financial institutions.

INVESTMENT STRATEGY. The Portfolio may borrow money from banks and enter into reverse repurchase agreements with banks and other financial institutions in amounts not exceeding one-fourth of the value of its total assets (including the amount borrowed). The Portfolio may enter into reverse repurchase agreements when the Investment Adviser expects that the interest income to be earned from the investment of the transaction proceeds will be greater than the related interest expense.

SPECIAL RISKS. Borrowings and reverse repurchase agreements involve leveraging. Reverse repurchase agreements involve the sale of money market securities held by the Portfolio subject to the Portfolio’s agreement to repurchase them at a mutually agreed upon date and price (including interest). If the securities held by the Portfolio decline in value while these transactions are outstanding, the NAV of the Portfolio’s outstanding shares will decline in value by proportionately more than the decline in value of the securities. In addition, reverse repurchase agreements involve the risks that (a) the interest income earned by the Portfolio (from the investment of the proceeds) will be less than the interest expense of the transaction; (b) the market value of the securities sold by the Portfolio will decline below the price the Portfolio is obligated to pay to repurchase the securities; and (c) the securities may not be returned to the Portfolio.

CREDIT FACILITY AND BORROWING. The Portfolio and affiliated funds of Northern Funds (each a “Fund”, and together the “Funds”) have jointly entered into a revolving credit facility (the “Credit Facility”) whereby the Portfolio, the other portfolios in the Trust, and the Funds may borrow for the temporary funding of shareholder redemptions or for other temporary or emergency purposes. Pursuant to the Credit Facility, the participating portfolios and Funds may borrow up to an aggregate commitment amount of $250 million (the “Commitment Limit”) at any time, subject to asset coverage and other limitations as specified in the Credit Facility and under the 1940 Act. The Portfolio may borrow up to the maximum amount allowable under its current prospectus and SAI, subject to various other legal, regulatory or contractual limits, including the asset coverage limits in the Credit Facility.

Borrowing results in interest expense and other fees and expenses for the Portfolio that may impact the Portfolio’s expenses, including any net expense ratios. The costs of borrowing may reduce the Portfolio’s yield. If the Portfolio borrows pursuant to the Credit Facility, it is charged interest at a variable rate. The Portfolio also pays a commitment fee equal to its pro rata share of the unused portion of the Credit Facility. The availability of funds under the Credit Facility can be affected by other participating portfolios’ or Funds’ borrowings under the Credit Facility. As such, the Portfolio may be unable to borrow (or borrow further) under the Credit Facility if the Commitment Limit has been reached.

CREDIT (OR DEFAULT) RISK (principal risk for the Portfolio). Credit (or default) risk is the risk that an issuer of fixed-income securities held by the Portfolio may default on its obligation to pay interest and repay principal. Generally, the lower the credit rating of a security, the greater the risk that the issuer of the security will default on its obligation. High quality securities are generally believed to have relatively low degrees of credit risk. The Portfolio intends to enter into financial transactions with counterparties that are creditworthy at the time of the transactions. There is always the risk that the Investment Adviser’s analysis of creditworthiness is incorrect or may change due to market conditions. Concerns over an issuer’s ability to make principal or interest payments may cause the value of a fixed income security to decline. To the extent that the Portfolio focuses its transactions with a limited number of counterparties, it will be more susceptible to the risks associated with one or more counterparties. In addition, the Portfolio may incur expenses in an effort to protect the Portfolio’s interests or enforce its rights against an issuer, guarantor or counterparty or may be hindered or delayed in exercising these rights.

CYBERSECURITY RISK (principal risk for the Portfolio). With the increased use of the Internet and because information technology (“IT”) systems and digital data underlie most of the Portfolio’s operations, the Portfolio and its investment adviser, custodian, transfer agent, distributor and other service providers and the financial intermediaries of each (collectively “Service Providers”) are exposed to the risk that their

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operations and data may be compromised as a result of internal and external cyber-failures, breaches or attacks (“Cyber Risk”). This could occur as a result of malicious or criminal cyberattacks. Cyber-attacks include actions taken to: (i) steal or corrupt data maintained online or digitally, (ii) gain unauthorized access to or release confidential information, (iii) shut down the Portfolio or Service Provider website through denial-of-service attacks, or (iv) otherwise disrupt normal business operations. However, events arising from human error, faulty or inadequately implemented policies and procedures or other systems failures unrelated to any external cyber-threat may have effects similar to those caused by deliberate cyber-attacks.

Successful cyber-attacks or other cyber-failures or events affecting the Portfolio or its Service Providers may adversely impact the Portfolio or its shareholders. For instance, such attacks, failures or other events may interfere with the processing of shareholder transactions, impact the Portfolio’s ability to calculate its NAV, cause the release of private shareholder information or confidential Portfolio information, impede trading, or cause reputational damage. Such attacks, failures or other events could also subject the Portfolio or its Service Providers to regulatory fines, penalties or financial losses, reimbursement or other compensation costs, and/or additional compliance costs.

Insurance protection and contractual indemnification provisions may be insufficient to cover these losses. The Portfolio or its Service Providers may also incur significant costs to manage and control Cyber Risk. While the Portfolio and its Service Providers have established IT and data security programs and have in place business continuity plans and other systems designed to prevent losses and mitigate Cyber Risk, there are inherent limitations in such plans and systems, including the possibility that certain risks have not been identified or that cyber-attacks may be highly sophisticated. Furthermore, the Portfolio has limited ability to prevent or mitigate cybersecurity incidents affecting Service Providers, and such Service Providers may have limited indemnification obligations to the Portfolio or its investment adviser, and the Portfolio cannot control the cybersecurity plans and systems put in place by the Service Providers or any other third parties whose operations may affect the Portfolio or its shareholders. The Portfolio and its shareholders could be negatively impacted as a result.

Cyber Risks are also present for issuers of securities or other instruments in which the Portfolio invests, which could result in material adverse consequences for such issuers, and may cause the Portfolio’s investment in such issuers to lose value.

DERIVATIVES. The Portfolio may purchase certain “derivative” instruments. A derivative is a financial instrument whose value is derived from, or based upon, the performance of underlying assets, interest rates, or other indices. Derivatives include structured securities such as collateralized mortgage obligations and other types of asset-backed securities, “stripped” securities and various floating rate instruments.

INVESTMENT STRATEGY. The Portfolio may invest in derivatives when the Investment Adviser believes the potential risks and rewards are consistent with the Portfolio’s objective, strategies and overall risk profile.

SPECIAL RISKS. Engaging in derivative transactions involves special risks, including (a) market risk that the Portfolio’s derivatives position will lose value; (b) credit risk that the counterparty to the transaction will default; (c) leveraging risk that the value of the derivative instrument will decline more than the value of the assets on which it is based; (d) risks pertaining to illiquid investments that the Portfolio will be unable to sell its position because of lack of market depth or disruption; (e) pricing risk that the value of a derivative instrument will be difficult to determine; and (f) operations risk that loss will occur as a result of inadequate systems or human error. Many types of derivatives have been developed recently and have not been tested over complete market cycles. For these reasons, the Portfolio may suffer a loss whether or not the analysis of the Investment Adviser is accurate.

GUARANTOR (OR CREDIT ENHANCEMENT) RISK. Guarantor (or credit enhancement risk) is the risk that changes in credit quality of a U.S. or foreign bank, insurance company or other financial institution or such entity’s failure to fulfill its obligations could cause the Portfolio’s investments in securities backed by guarantees, letters of credit, insurance or other credit enhancements issued by such bank or institution to decline in value. Guarantees, letters of credit, insurance or other credit enhancements do not protect the Portfolio or its shareholders from losses caused by declines in a security’s market value. In addition, having multiple securities’ credit enhanced by the same enhancement provider will increase the adverse effects on the Portfolio that are likely to result from a downgrading of, or a default by, such enhancement provider. Adverse developments in the banking or bond insurance industries also may negatively affect the Portfolio.

ILLIQUID OR RESTRICTED INVESTMENTS. An illiquid investment is an investment that the Portfolio reasonably expects cannot be sold or disposed of in the ordinary course of business within seven calendar days at approximately the value ascribed to it by the Portfolio. Illiquid securities include repurchase agreements and time deposits with notice/termination dates of more than seven days, certain variable amount master demand notes that cannot be called within seven days, certain insurance funding agreements, derivative instruments, and securities and other financial instruments that are not readily marketable, and 144A

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Securities (as defined below), and both foreign and domestic securities that are not readily marketable, unless, based upon a review of the relevant market, trading and investment-specific considerations, those investments are determined not to be illiquid.

INVESTMENT STRATEGY. The Portfolio may invest up to 5% of its total assets in illiquid investments, as such term is defined in Rule 2a-7 under the 1940 Act. A domestically traded security that is not registered under the Securities Act of 1933, as amended (the “1933 Act”) will not be considered illiquid if the Investment Adviser determines that an adequate trading market exists for that security. If otherwise consistent with its investment objectives and strategies, the Portfolio may purchase commercial paper issued pursuant to Section 4(a)(2) of the 1933 Act and securities that are not registered under the 1933 Act but can be sold to “qualified institutional buyers” in accordance with Rule 144A under the 1933 Act (“Rule 144A Securities”). These securities will not be considered illiquid so long as the Investment Adviser determines that, under guidelines approved by the Trust’s Board of Trustees, an adequate trading market exists.

SPECIAL RISKS. Because illiquid and restricted investments may be difficult to sell at an acceptable price, they may be subject to greater volatility and may result in a loss to the Portfolio. The practice of investing in Rule 144A Securities and commercial paper available to qualified institutional buyers could increase the level of the Portfolio’s illiquidity during any period that qualified institutional buyers become uninterested in purchasing these securities. Investments purchased by the Portfolio that are liquid at the time of purchase may subsequently become illiquid due to events relating to the issuer, market events, economic conditions and/or investor perception. To the extent an investment held by the Portfolio is deemed to be an illiquid investment or a less liquid investment, the Portfolio will be exposed to greater liquidity risk.

INCOME RISK (principal risk for the Portfolio) 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.

INTEREST RATE RISK (principal risk for the Portfolio). The Portfolio’s yield will vary with changes in interest rates During periods of rising interest rates, the Portfolio’s yield (and the market value of its securities) will tend to be lower than prevailing market rates; in periods of falling interest rates, the Portfolio’s yield (and the market value of its securities) will tend to be higher. In a period of rising interest rates, the Portfolio’s yield may not rise as quickly as the yields of certain other short-term investments. Investments held by the Portfolio with longer maturities will tend to be more sensitive to interest rate changes than investments with shorter maturities. If interest rates rise, the Portfolio’s yield may not increase proportionately.

Interest rates in the U.S. are currently at historically low levels. A low or negative interest rate environment poses additional risks to the Portfolio, which are heightened in a very low or negative interest rate environment. Changing interest rates may have unpredictable effects on the markets and the Portfolio’s investments. A low interest rate environment may cause the Portfolio’s earnings to fall below the Portfolio’s expense ratio, resulting in a low or negative yield and a decline in the Portfolio’s share price. Additionally, securities issued or guaranteed by the U.S. government, its agencies, instrumentalities and sponsored enterprises have historically involved little risk of loss of principal if held to maturity. However, due to fluctuations in interest rates, the market value of such securities held by the Portfolio may vary.

INTERFUND BORROWING AND LENDING. The SEC has granted an exemption permitting the Portfolio to participate in an interfund borrowing and lending program. This interfund borrowing and lending program allows the Portfolio to borrow money from other portfolios in the Trust and other affiliated funds of Northern Funds (each a “Fund” and together the “Funds”) advised by NTI, and to lend money to other portfolios in the Trust, for temporary or emergency purposes. The interfund borrowing and lending program is currently not operational. The interfund borrowing and lending program is subject to a number of conditions, including, among other things, the requirements that (1) the Portfolio may not borrow or lend money through the program unless it receives a more favorable interest rate than is available from a bank loan rate or investment yield rate, respectively; (2) loans will be secured on an equal priority basis with at least an equivalent percentage of collateral to loan value as any outstanding bank loan that requires collateral; (3) loans will have a maturity no longer than that of any outstanding bank loan (and in any event not over seven days); (4) if an event of default occurs under any agreement evidencing an outstanding bank loan to the Portfolio, the event of default will automatically (without need for action or notice by the lending Portfolio or Fund) constitute an immediate event of default under the Interfund Lending Agreement entitling the lending Portfolio or Fund to call the interfund loan (and exercise all rights with respect to any collateral) and that such call will be made if the bank exercises its right to call its loan under its agreement with the Portfolio; (5) the Portfolio may not borrow money if the loan would cause its outstanding borrowings from all sources to exceed 10% of its net assets at the time of the loan, except that the Portfolio may borrow up to 33 1/3% of its total assets through the program or from other sources if each interfund loan is secured by the pledge of segregated collateral with a market

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value of at least 102% of the outstanding principal value of the loan; (6) the Portfolio may not loan money if the loan would cause its aggregate outstanding loans through the program to exceed 15% of its net assets at the time of the loan; (7) the Portfolio’s interfund loans to any one Portfolio shall not exceed 5% of the lending Portfolio’s net assets; and (8) the Portfolio’s borrowings through the program will not exceed the greater of 125% of the Portfolio’s total net cash redemptions or 102% of the Portfolio’s sales fails (when a sale of securities “fails,” due to circumstances beyond the Portfolio’s control) for the preceding seven calendar days as measured at the time of the loan. In addition, the Portfolio may participate in the interfund borrowing and lending program only if and to the extent that such participation is consistent with the Portfolio’s investment objective and policies. The Board of Trustees of the Trust is responsible for overseeing the interfund borrowing and lending program. A delay in repayment to a lending Portfolio could result in a lost investment opportunity or additional lending costs.

INVESTMENT COMPANIES. To the extent consistent with its investment objectives and strategies, the Portfolio may invest in securities issued by other affiliated or unaffiliated investment companies.

INVESTMENT STRATEGY. Investments by the Portfolio in other investment companies will be subject to the limitations of the 1940 Act and SEC orders. Although the Portfolio does not expect to do so in the foreseeable future, the Portfolio is authorized to invest substantially all of its assets in an open-end investment company or a series thereof that has substantially the same investment objective, strategies and fundamental restrictions as the Portfolio.

SPECIAL RISKS. As a shareholder of another investment company, the Portfolio would be subject to the same risks as any other investor in that company. It would also bear a proportionate share of any fees or expenses paid by that company. These expenses would be in addition to the management fees and other expenses the Portfolio bears directly in connection with its own operations. In October 2020, the SEC adopted certain regulatory changes and took other actions related to the ability of an investment company to invest in another investment company. These regulatory changes may adversely impact the Portfolio’s investment strategies and operations.

LARGE SHAREHOLDER RISK (principal risk for the Portfolio). To the extent a significant percentage of the shares of the Portfolio are owned or controlled by a small number of account shareholders (or a single account shareholder), including funds or accounts over which the Investment Adviser or an affiliate of the Investment Adviser has investment discretion, the Portfolio is subject to the risk that those shareholders may purchase or redeem Portfolio shares in significant amounts rapidly or unexpectedly, including as a result of an asset allocation decision made by the Investment Adviser or an affiliate of the Investment Adviser and may adversely affect the Portfolio’s performance if the Investment Adviser is forced to sell portfolio securities or invest cash when the Investment Adviser would not otherwise choose to do so. Redemptions of a large number of shares may affect the liquidity of the Portfolio, increase the Portfolio’s transaction costs, and accelerate the realization of taxable income and/or gains.

Such sales may also accelerate the increase of taxable income to shareholders if these sales result in gains, and may also increase transaction costs. In addition, a large redemption could result in the Portfolio’s current expenses being allocated over a smaller asset base, leading to an increase in each such Portfolio’s expense ratio. Similarly, large purchases of the Portfolio’s shares may adversely affect the Portfolio’s performance to the extent that the Portfolio is delayed in investing new cash or otherwise maintain a larger cash position than they ordinarily would.

LIBOR TRANSITION. The Portfolio’s investments, payment obligations and financing terms may be based on floating rates, such as London Interbank Offered Rate (“LIBOR”). On July 27, 2017, the Chief Executive of the United Kingdom (“UK”) Financial Conduct Authority (“FCA”), which regulates LIBOR, announced a desire to phase out the use of LIBOR by the end of 2021. Although many LIBOR rates will be phased out at the end of 2021 as originally intended, a selection of widely used USD LIBOR rates will continue to be published until June 2023 in order to assist with the transition. There remains uncertainty regarding the effect of the LIBOR transition process and therefore any impact of a transition away from LIBOR on the instruments in which the Portfolio invests cannot yet be determined. There is no assurance that the composition or characteristics of any alternative reference rate will be similar to or produce the same value or economic equivalence as LIBOR or that instruments using an alternative rate will have the same volume or liquidity. This announcement and any additional regulatory or market changes that occur as a result of the transition away from LIBOR and the adoption of alternative reference rates may have an adverse impact on the value of the Portfolio’s investments, performance or financial condition, and might lead to increased volatility and illiquidity in markets that currently rely on LIBOR to determine interest rates.

LIQUIDITY RISK. Liquidity risk is the risk that the Portfolio will not be able to pay redemption proceeds within the time periods described in this Prospectus because of unusual market conditions, an unusually high volume of redemption requests, legal restrictions impairing its ability to sell particular securities or close derivative positions at an advantageous market price or

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other reasons. Certain portfolio securities may be less liquid than others, which may make them difficult or impossible to sell at the time and the price that the Portfolio would like or difficult to value. The Portfolio may have to lower the price, sell other securities instead or forgo an investment opportunity. In addition, certain assets that the Portfolio wants to buy may be difficult or impossible to purchase. Any of these events could have a negative effect on portfolio management or performance. Liquidity risk may be the result of, among other things, the reduced number and capacity of traditional market participants to make a market in fixed income securities. As a general matter, dealers recently have been less willing to make markets for fixed income securities. The potential for liquidity risk may be magnified by a rising interest rate environment or other circumstances where investor redemptions from money market and other fixed income mutual funds may be higher than normal, potentially causing increased supply in the market due to selling activity. Portfolios with principal investment strategies that involve investments in securities of companies with smaller market capitalizations, foreign securities, derivatives or securities with potential market and/or credit risk tend to have the greatest exposure to liquidity risk. All of these risks may increase during periods of market volatility. The liquidity of certain assets, such as privately issued and non-investment grade mortgage-and asset-backed securities, may be difficult to ascertain and may change over time. Transactions in less liquid securities may entail transaction costs that are higher than those for transactions in more liquid securities.

MARKET EVENTS RISK. Market events risk relates to the increased volatility, depressed valuations, decreased liquidity and heightened uncertainty in the financial markets throughout the world during the past decade. These conditions may recur.

The U.S. government and the Federal Reserve, as well as certain foreign governments and central banks, have taken steps to support financial markets, including by keeping interest rates at historically low levels. This and other government intervention may not work as intended, particularly if the efforts are perceived by investors as being unlikely to achieve the desired results. Certain foreign governments and central banks have implemented so-called negative interest rates (e.g., charging depositors who keep their cash at a bank) to spur economic growth. Governmental or central bank actions, including interest rate increases, measures to address budget deficits, or contrary actions by different governments, as well as downgrades of sovereign debt, fluctuations in oil and commodity prices, dramatic changes in currency exchange rates and geopolitical events (including war and terror attacks) could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the Portfolio invests.

Policy and legislative changes in the United States and in other countries (such as Brexit, as further discussed below) may also contribute to decreased liquidity and increased volatility in the financial markets. Political turmoil within the U.S. and abroad may also impact the Portfolio. Although the U.S. government has historically honored its credit obligations, it remains possible that the U.S. could default on its obligations. While it is impossible to predict the consequences of such an unprecedented event, it is likely that a default by the U.S. would be highly disruptive to the U.S. and global securities markets and could significantly impair the value of the Portfolio’s investments. Similarly, political events within the United States at times have resulted, and may in the future result, in a shutdown of government services, which could negatively affect the U.S. economy, decrease the value of many Portfolio investments, and increase uncertainty in or impair the operation of the U.S. or other securities markets.

Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, terrorism, natural disasters, public health emergencies (including pandemics and epidemics) and other circumstances in one country or region could have profound impacts on global economies or markets. As a result, whether or not the Portfolio directly invests in securities of issuers located in or with significant exposure to the countries directly affected, the value and liquidity of the Portfolio’s investments may be negatively affected.

In June 2016, the UK approved a referendum to leave the EU. The withdrawal, known colloquially as “Brexit”, was agreed to and ratified by the UK Parliament, and the UK left the EU on January 31, 2020. It began a transition period in which to negotiate a new trading relationship for goods and services that ended on December 31, 2020. On January 1, 2021, the UK left the EU Single Market and Customs Union, as well as all EU policies and international agreements. On December 24, 2020, the UK and EU agreed to a trade deal with no tariffs or quotas on products, regulatory and customs cooperation mechanisms as well as provisions ensuring a level playing field for open and fair competition. The UK and EU also plan to put in place a regulatory dialogue on financial systems based on a separate memorandum of understanding in 2021. Since the referendum, there have been periods of significant volatility in the global stock markets and currency exchange rates, as well as challenging market conditions in the UK. At this time, the impact that the trade deal and any future agreements on services, particularly financial services, will have on the Portfolio cannot be predicted, and it is possible that the new terms may adversely affect the Portfolio.

RECENT MARKET EVENTS. Periods of unusually high financial market volatility and restrictive credit conditions, at times

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limited to a particular sector or geographic area, have occurred in the past and may be expected to recur in the future. Some countries, including the United States, have adopted or have signaled protectionist trade measures, relaxation of the financial industry regulations that followed the financial crisis, and/or reductions to corporate taxes. The scope of these policy changes is still developing, but the equity and debt markets may react strongly to expectations of change, which could increase volatility, particularly if a resulting policy runs counter to the market’s expectations. The outcome of such changes cannot be foreseen at the present time. In addition, geopolitical and other risks, including environmental and public health risks, may add to instability in the world economy and markets generally. As a result of increasingly interconnected global economies and financial markets, the value and liquidity of the Portfolio’s investments may be negatively affected by events impacting a country or region, regardless of whether the Portfolio invests in issuers located in or with significant exposure to such country or region.

Recent events are impacting the securities markets. An outbreak of respiratory disease caused by a novel coronavirus was first detected in December 2019 and has spread internationally. The outbreak and efforts to contain its spread have resulted in closing borders and quarantines, restricting international and domestic travel, enhanced health screenings, cancellations, disrupted supply chains and customer activity, responses by businesses (including changes to operations and reducing staff), and have produced general concern and uncertainty. The impact of the coronavirus pandemic, and other epidemics and pandemics that may arise in the future, could adversely affect national and global economies, individual companies and the market in general in a manner and for a period of time that cannot be foreseen at the present time. Health crises caused by the outbreak may heighten other pre-existing political, social and economic risks in a country or region. Governmental authorities and regulators throughout the world, such as the U.S. Federal Reserve, have in the past responded to major economic disruptions with changes to fiscal and monetary policy, including but not limited to, direct capital infusions, new monetary programs, and dramatically lower interest rates. Certain of those policy changes are being implemented in response to the coronavirus outbreak. Such policy changes may adversely affect the value, volatility and liquidity of dividend and interest paying securities. In certain cases, an exchange or market may close or issue trading halts on either specific securities or even the entire market, which may result in the Portfolio being, among other things, unable to buy or sell certain securities or financial instruments or to accurately price its investments. In the event of a pandemic or an outbreak, there can be no assurance that the Portfolio and its Service Providers will be able to maintain normal business operations for an extended period of time or will not lose the services of key personnel on a temporary or long-term basis due to illness or other reasons. A pandemic or disease could also impair the information technology and other operational systems upon which the Portfolio’s investment adviser relies, and could otherwise disrupt the ability of the Portfolio’s service providers to perform essential tasks. Although multiple asset classes may be affected by a market disruption, the duration and effects may not be the same for all types of assets. To the extent the Portfolio may overweight its investments in certain countries, companies, industries or market sectors, such position will increase the Portfolio’s exposure to risk of loss from adverse developments affecting those countries, companies, industries or sectors. These conditions could result in the Portfolio’s inability to achieve its investment objectives, cause the postponement of reconstitution or rebalance dates for benchmark indices, adversely affect the prices and liquidity of the securities and other instruments in which the Portfolio invests, negatively impacting the Portfolio’s performance, and cause losses on your investments in the Portfolio. You should also review this prospectus and the SAI to understand the Portfolio’s discretion to implement temporary defensive measures, as well as the circumstances in which the Portfolio may satisfy redemption requests in-kind.

OPERATIONAL RISK. The Investment Adviser to the Portfolio and other Portfolio service providers may be subject to operational risk and may experience disruptions and operating errors. In particular, these errors or failures in systems and technology, including operational risks associated with reliance on third party service providers, may adversely affect the Portfolio’s ability to calculate its NAVs in a timely manner, including over a potentially extended period. Moreover, disruptions (for example, pandemics and health crises) that cause prolonged periods of remote work or significant employee absences at the Portfolio’s service providers could impact the ability to conduct the Portfolio’s operations. While service providers are required to have appropriate operational risk management policies and procedures in place, their methods of operational risk management may differ from those of the Portfolio in the setting of priorities, the personnel and resources available or the effectiveness of relevant controls. The Investment Adviser, through its monitoring and oversight of service providers, seeks to ensure that service providers take appropriate precautions to avoid and mitigate risks that could lead to disruptions and operating errors. However, it is not possible for the Investment Adviser or other Portfolio service providers to identify all of the operational risks that may affect the Portfolio or to develop processes and controls to completely eliminate or mitigate their occurrence or effects.

REPURCHASE AGREEMENTS (principal strategy for the Portfolio). Repurchase agreements involve the purchase of securities by

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the Portfolio subject to the seller’s agreement to repurchase them at a mutually agreed upon date and price.

INVESTMENT STRATEGY. To the extent consistent with its investment objective and principal investment strategies, the Portfolio may enter into repurchase agreements with domestic and foreign financial institutions such as banks and broker-dealers that are deemed to be creditworthy by the Investment Adviser. Although the securities subject to a repurchase agreement may have maturities exceeding one year, settlement of the agreement generally will not occur more than one year after the Portfolio acquires the securities.

SPECIAL RISKS. In the event of a default, the Portfolio will suffer a loss to the extent that the proceeds from the sale of the underlying securities and other collateral are less than the repurchase price and the Portfolio’s costs associated with delay and enforcement of the repurchase agreement. In addition, in the event of bankruptcy, the Portfolio could suffer additional losses if a court determines that the Portfolio’s interest in the collateral is unenforceable by the Portfolio. If the Portfolio enters into a repurchase agreement with a foreign financial institution, it may be subject to the same risks associated with foreign investments. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments, the imposition of economic sanctions against a particular country or countries, organizations, entities and/or individuals, changes in international trading patterns, trade barriers, and other protectionist or retaliatory measures.

International trade barriers or economic sanctions against foreign countries, organizations, entities and/or individuals may adversely affect the credit worthiness of a foreign financial institution. Additionally, foreign banks and foreign branches of domestic banks may be subject to less stringent reserve requirements and to different accounting, auditing and recordkeeping requirements.

The Portfolio intends to enter into transactions with counterparties that are creditworthy at the time of the transactions. There is always the risk that the Investment Adviser’s analysis of creditworthiness is incorrect or may change due to market conditions. To the extent that the Portfolio focuses its transactions with a limited number of counterparties, it will be more susceptible to the risks associated with one or more counterparties.

With respect to collateral received in repurchase transactions or other investments, the Portfolio may have significant exposure to the financial services and mortgage markets. Such exposure, depending on market conditions, could have a negative impact on the Portfolio, including minimizing the value of any collateral.

STRIPPED SECURITIES. These securities are issued by the U.S. government (or an agency, instrumentality or a sponsored enterprise), foreign governments, banks and other issuers. They entitle the holder to receive either interest payments or principal payments that have been “stripped” from a debt obligation. These obligations include stripped mortgage-backed securities, which are derivative multi-class mortgage securities.

The Treasury Department has facilitated transfers of ownership of zero coupon securities by accounting separately for the beneficial ownership of particular interest coupon and principal payments on Treasury securities through the Federal Reserve book-entry record-keeping system. The Federal Reserve program as established by the Treasury Department is known as “Separate Trading of Registered Interest and Principal of Securities” or “STRIPS.” Under the STRIPS program, the Portfolio will be able to have its beneficial ownership of zero coupon securities recorded directly in the book-entry record-keeping system in lieu of having to hold certificates or other evidences of ownership of the underlying U.S. Treasury securities.

INVESTMENT STRATEGY. To the extent consistent with its investment objectives and strategies, the Portfolio may purchase stripped securities, including securities registered in the STRIPS program.

SPECIAL RISKS. Stripped securities are very sensitive to changes in interest rates and to the rate of principal prepayments. A rapid or unexpected change in either interest rates or principal prepayments could depress the price of stripped securities held by the Portfolio and adversely affect the Portfolio’s investment performance.

STRUCTURED SECURITIES. The value of such securities is determined by reference to changes in the value of specific currencies, interest rates, commodities, securities, indices or other financial indicators (the “Reference”) or the relative change in two or more References. The interest rate or the principal amount payable upon maturity or redemption may be increased or decreased depending upon changes in the applicable Reference. Examples of structured securities include, but are not limited to, asset-backed commercial paper, structured notes and other debt obligations, where the principal repayment at maturity is determined by the value of a specified security or securities index.

INVESTMENT STRATEGY. The Portfolio may invest in structured securities to the extent consistent with its investment objectives and strategies.

SPECIAL RISKS. Structured securities present additional risk that the interest paid to the Portfolio on a structured security will be less than expected. The terms of some structured securities may provide that in certain circumstances no principal is due at

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maturity and, therefore, the Portfolio could suffer a total loss of its investment. Structured securities may be positively or negatively indexed, so that appreciation of the Reference may produce an increase or decrease in the interest rate or value of the security at maturity. In addition, changes in the interest rates or the value of the security at maturity may be a multiple of changes in the value of the Reference. Consequently, structured securities may entail a greater degree of market risk than other types of securities. Structured securities also may be more volatile, less liquid and more difficult to accurately price than less complex securities due to their derivative nature.

TEMPORARY INVESTMENTS. For capital preservation and liquidity, the Portfolio may have a greater concentration in short-term securities, and including investing up to all of its assets in overnight securities, which may result in a reduction of the Portfolio’s yield.

Although the Investment Adviser has the ability to take temporary positions, it may choose not to do so for a variety of reasons, even during volatile market conditions.

U.S. GOVERNMENT OBLIGATIONS (principal strategy for the Portfolio). These instruments include U.S. Treasury obligations, such as bills, notes and bonds, which generally differ only in terms of their interest rates, maturities and time of issuance. They also include obligations issued or guaranteed by the U.S. government or by its agencies, instrumentalities or sponsored enterprises. Securities guaranteed as to principal and interest by the U.S. government or by its agencies, instrumentalities or sponsored enterprises are deemed to include (a) securities for which the payment of principal and interest is backed by an irrevocable letter of credit issued by the U.S. government or by an agency, instrumentality or sponsored enterprise thereof and (b) participations in loans made to foreign governments or their agencies that are so guaranteed. U.S. treasury obligations also include floating rate public obligations of the U.S. Treasury.

INVESTMENT STRATEGY. To the extent consistent with its investment objective and strategies, the Portfolio may invest in a variety of U.S. Treasury obligations and in other obligations issued or guaranteed by the U.S. government or by its agencies, instrumentalities or sponsored enterprises.

SPECIAL RISKS. Not all U.S. government obligations carry the same credit support. Although many U.S. government securities are issued by entities chartered or sponsored by Acts of Congress, such as the Federal National Mortgage Association (“Fannie Mae”), the Federal Home Loan Mortgage Corporation (“Freddie Mac”) and the Federal Home Loan Banks, such securities are neither issued nor guaranteed by the U.S. Treasury and, therefore, are not backed by the full faith and credit of the United States. Some, such as those of the Government National Mortgage Association (“Ginnie Mae”), are supported by the full faith and credit of the U.S. Treasury, although this guarantee applies only to principal and interest payments and does not apply to losses resulting from declines in the market value of these securities. Other obligations, such as those of the Federal Home Loan Banks, are supported by the right of the issuer to borrow from the U.S. Treasury; and others are supported by the discretionary authority of the U.S. government to purchase the agency’s obligations. Still others are supported only by the credit of the instrumentality or sponsored enterprise. The maximum potential liability of the issuers of some U.S. government securities may greatly exceed their current resources, including their legal right to support from the U.S. Treasury. It is possible that these issuers will not have the funds to meet their payment obligations in the future. No assurance can be given that the U.S. government would provide financial support to its agencies, instrumentalities or sponsored enterprises if it is not obligated to do so by law. In addition, the secondary market for certain participations in loans made to foreign governments or their agencies may be limited.

An agency of the U.S. government has placed Fannie Mae and Freddie Mac into conservatorship, a statutory process with the objective of returning the entities to normal business operations. It is unclear what effect this conservatorship will have on the securities issued or guaranteed by Fannie Mae or Freddie Mac. As a result, these securities are subject to more credit risk than U.S. government securities that are supported by the full faith and credit of the United States (e.g., U.S. Treasury bonds).

To the extent the Portfolio invests in debt instruments or securities of non-U.S. government entities that are backed by the full faith and credit of the United States, pursuant to the FDIC Debt Guarantee Program (the “Debt Guarantee Program”) or other similar programs, there is a possibility that the guarantee provided under the Debt Guarantee Program or other similar programs may be discontinued or modified at a later date.

Floating rate public obligations of the U.S. Treasury (“Floating Rate Notes” or “FRNs”) have interest rates that adjust periodically. FRNs’ floating interest rates may be higher or lower than the interest rates of fixed-rate bonds of comparable quality with similar maturities. Securities with 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 FRNs, which only occur periodically (see “Variable and Floating Rate Instruments” below).

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VARIABLE AND FLOATING RATE INSTRUMENTS (principal risk for the Portfolio). Variable and floating rate instruments have interest rates that periodically are adjusted either at set intervals or that float at a margin tied to a specified index rate. These instruments include floating rate Treasury obligations, variable amount master demand notes and long-term variable and floating rate bonds (sometimes referred to as “Put Bonds”) where the Portfolio obtains at the time of purchase the right to put the bond back to the issuer or a third party at par at a specified date.

INVESTMENT STRATEGY. The Portfolio may invest in variable or floating rate instruments to the extent consistent with its investment objective and strategies.

SPECIAL RISKS. Variable and floating rate instruments are subject to many of the same risks as fixed rate instruments, particularly credit risk and default risk, which could impede their value. Because there is no active secondary market for certain variable and floating rate instruments, they may be more difficult to sell if the issuer defaults on its payment obligations or during periods when the Portfolio is not entitled to exercise its demand rights. As a result, the Portfolio could suffer a loss with respect to these instruments. In addition, variable and floating rate instruments are subject to changes in value based on changes in market interest rates or changes in the issuer’s or guarantor’s creditworthiness. In addition, there may be a lag between an actual change in the underlying interest rate benchmark and the reset time for an interest payment of a variable or floating instrument, which could harm or benefit the Portfolio, depending on the interest rate environment or other circumstances. In a rising interest rate environment, for example, a floating or variable rate instrument that does not reset immediately would prevent the Portfolio from taking full advantage of rising interest rates in a timely manner.

In 2017, the FCA warned that LIBOR may cease to be available or appropriate for use by 2021. The unavailability or replacement of LIBOR may affect the value, liquidity or return on certain Portfolio investments and may result in costs incurred in connection with closing out positions and entering into new trades. Any pricing or adjustments to the Portfolio’s investments resulting from a substitute reference rate may adversely affect the Portfolio’s performance and/or NAV (See “LIBOR Transition” above).

WHEN-ISSUED SECURITIES, DELAYED DELIVERY TRANSACTIONS AND FORWARD COMMITMENTS. A purchase of “when-issued” securities refers to a transaction made conditionally because the securities, although authorized, have not yet been issued. A delayed delivery or forward commitment transaction involves a contract to purchase or sell securities for a fixed price at a future date beyond the customary settlement period.

INVESTMENT STRATEGY. The Portfolio may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Although the Portfolio generally would purchase securities in these transactions with the intention of acquiring the securities, the Portfolio may dispose of such securities prior to settlement if the Investment Adviser deems it appropriate to do so.

SPECIAL RISKS. Purchasing securities on a when-issued, delayed delivery or forward commitment basis involves the risk that the value of the securities may decrease by the time they actually are issued or delivered. Conversely, selling securities in these transactions involves the risk that the value of the securities may increase by the time they actually are issued or delivered.

Therefore, these transactions may have a leveraging effect on the Portfolio, making the value of an investment in the Portfolio more volatile and increasing the Portfolio’s overall investment exposure. These transactions also involve the risk that the counterparty may fail to deliver the security or cash on the settlement date. If this occurs, the Portfolio may lose both the investment opportunity for the assets it set aside to pay for the security and any gain in the security’s price.

OTHER SECURITIES. Additionally, the Portfolio may purchase other types of securities or instruments similar to those described in these sections if otherwise consistent with the Portfolio’s investment objectives and strategies. You should carefully consider the risks discussed in these sections before investing in the Portfolio.

The Portfolio may invest in other securities and is subject to further restrictions and risks that are described in the SAI. Additional information about the Portfolio, its investments and related risks can also be found in “Investment Objectives and

Strategies” in the SAI.

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FINANCIAL HIGHLIGHTS

THE FINANCIAL HIGHLIGHTS TABLE IS INTENDED TO HELP YOU UNDERSTAND THE FINANCIAL PERFORMANCE OF THE PORTFOLIO’S SHARES FOR THE PAST FIVE YEARS. BECAUSE THE SIEBERT WILLIAMS SHANK SHARES ARE A NEW CLASS OF SHARES OF THE PORTFOLIO, INFORMATION IS SHOWN FOR THE PORTFOLIO’S SHARES CLASS, WHICH IS OFFERED IN A SEPARATE PROSPECTUS.

Certain information reflects the financial results for a single Shares Class share. The total returns in the tables represent the rate that an investor would have earned (or lost) on an investment in Shares Class shares of the Portfolio held for the entire period (assuming reinvestment of all dividends and distributions).

The information for the six-month period ended May 31 has been derived from the Portfolio’s unaudited semiannual financial statements included in the Portfolio’s semiannual report dated May 31, 2021. The information for the fiscal year ended November 30 has been derived from financial statements that have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, whose report, along with the Portfolio’s financial statements, are included in the Portfolio’s annual report. Information for fiscal years prior to November 30, 2017 was audited by the Portfolio’s former independent registered public accounting firm. Copies of the semiannual and annual report are available upon request and without charge. The Portfolio’s annual report, which is available upon request and without charge by calling 800-637-1380, is also available on the Trust’s website at https://www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-institutional/money-market/NITXX or by following the hyperlink: https://www.sec.gov/Archives/edgar/data/0000710124/000119312521030333/d106269dncsr.htm.

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NORTHERN INSTITUTIONAL FUNDS

(THE “TRUST”)

STATEMENT OF ADDITIONAL INFORMATION

December 6, 2021

TREASURY PORTFOLIO

SIEBERT WILLIAMS SHANK SHARES (SWSXX)

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This Statement of Additional Information dated December 6, 2021 (the “SAI”) is not a prospectus. This SAI should be read in conjunction with the Prospectus dated December 6, 2021, as amended or supplemented from time to time, for the Siebert Williams Shank shares of the Treasury Portfolio (the “Portfolio”) of Northern Institutional Funds (the “Prospectus”). A copy of the Prospectus may be obtained without charge by calling 800-637-1380 (toll-free). Capitalized terms not otherwise defined have the same meaning as in the Prospectus.

The audited financial statements for the Portfolio and related report of Deloitte & Touche LLP, an independent registered public accounting firm, contained in the Annual Report to the Portfolio’s shareholders for the fiscal year ended November 30, 2020, as well as the unaudited financial statements of the Portfolio contained in the Portfolio’s semiannual report to shareholders for the six-month period ended May 31, 2021, are incorporated herein by reference in the section entitled “Financial Statements.” Information in the financial statements for periods prior to the fiscal year ended November 30, 2017 were audited by the Portfolio’s former independent registered public accounting firm. No other part of the annual report or semiannual report is incorporated by reference herein. Copies of the annual report and the semiannual report may be obtained upon request and without charge by calling 1-800-637-1380 (toll-free).

NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY REPRESENTATIONS NOT CONTAINED IN THIS SAI OR IN THE PROSPECTUS IN CONNECTION WITH THE OFFERING MADE BY THE PROSPECTUS AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE TRUST OR ITS DISTRIBUTOR. THE PROSPECTUS DOES NOT CONSTITUTE AN OFFERING BY THE TRUST OR BY THE DISTRIBUTOR IN ANY JURISDICTION IN WHICH SUCH OFFERING MAY NOT LAWFULLY BE MADE.

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, it cannot guarantee it will do so.

An investment in the Portfolio is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation (“FDIC”), any other government agency, Siebert Williams Shank & Co., LLC or its affiliates, or The Northern Trust Company (“TNTC”), its affiliates, subsidiaries or any other bank. The Portfolio’s sponsor has no legal obligation to provide financial support to the Portfolio, and you should not expect that the sponsor will provide financial support to the Portfolio at any time.

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INDEX

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ADDITIONAL INVESTMENT INFORMATION

CLASSIFICATION AND HISTORY

Northern Institutional Funds (the “Trust”) is an open-end management investment company. The Portfolio is classified as diversified under the Investment Company Act of 1940, as amended (the “1940 Act”). The Portfolio is a series of the Trust, which was formed as a Delaware statutory trust on July 1, 1997 under an Agreement and Declaration of Trust (as amended from time to time, the “Trust Agreement”). The Trust is the result of a reorganization of a Massachusetts business trust formerly known as The Benchmark Funds on March 31, 1998. The Trust’s name was changed from The Benchmark Funds to Northern Institutional Funds on July 15, 1998. The Trust also offers other additional money market portfolios, which are not described in this SAI.

INVESTMENT OBJECTIVE AND STRATEGIES

The following supplements the investment objective, strategies and risks of the Portfolio as set forth in the Prospectus. The investment objective of the Treasury Portfolio may not be changed without shareholder approval. Except as expressly noted below, the Portfolio’s investment strategies may be changed without shareholder approval. In addition to the instruments discussed below and in the Prospectus, the Portfolio may purchase other types of financial instruments, however designated, whose investment and credit quality characteristics are determined by Northern Trust Investments, Inc. (“NTI” or the “Investment Adviser,” and collectively with TNTC, “Northern Trust”) to be substantially similar to those of any other investment otherwise permitted by the Portfolio’s investment strategies.

Treasury Portfolio seeks to achieve its objective by investing, under normal circumstances, its total assets exclusively in: cash; short-term bills, notes, including floating rate notes, and other obligations issued or guaranteed by the U.S. Treasury (“Treasury Obligations”); and repurchase agreements that are collateralized fully by cash or Treasury Obligations. The Portfolio, under normal circumstances, will invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in Treasury Obligations and repurchase agreements collateralized solely by Treasury Obligations.

To the extent required by Securities and Exchange Commission (“SEC”) regulations, shareholders of the Treasury Portfolio will be provided with sixty days’ notice in the manner prescribed by the SEC before any change in the Portfolio’s policy stated in the Prospectus to, under normal circumstances, invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in Treasury Obligations and repurchase agreements collateralized solely by Treasury Obligations. For these purposes, “net assets” include the amount of any borrowings for investment purposes and the amount of “net assets” is measured at the time of purchase.

The Treasury Portfolio operates as a “government money market fund” under Rule 2a-7 of the 1940 Act. 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 and/or a redemption gate on fund redemptions that might apply to other types of money market funds should certain triggering events specified in Rule 2a-7 occur.

BORROWINGS. The Portfolio may engage in borrowing transactions as a means of raising cash to satisfy redemption requests, for other temporary or emergency purposes or, to the extent permitted by its investment policies, to raise additional cash to be invested in other securities or instruments in an effort to increase the Portfolio’s investment returns. Reverse repurchase agreements may be considered to be a type of borrowing.

When the Portfolio invests borrowing proceeds in other securities, the Portfolio will be at risk for any fluctuations in the market value of the securities in which the proceeds are invested. Like other leveraging risks, this makes the value of an investment in the Portfolio more volatile and increases the Portfolio’s overall

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investment exposure. In addition, if the Portfolio’s return on its investment of the borrowing proceeds does not equal or exceed the interest that the Portfolio is obligated to pay under the terms of a borrowing, engaging in these transactions will lower the Portfolio’s return.

The Portfolio may be required to liquidate portfolio securities at a time when it would be disadvantageous to do so in order to make payments with respect to its borrowing obligations. This could adversely affect the Portfolio’s strategy and result in lower Portfolio returns. Interest on any borrowings will be the Portfolio expense and will reduce the value of the Portfolio’s shares. The Portfolio may borrow on a secured or on an unsecured basis. If the Portfolio enters into a secured borrowing arrangement, a portion of the Portfolio’s assets will be used as collateral. During the term of the borrowing, the Portfolio will remain at risk for any fluctuations in the market value of these assets in addition to any securities purchased with the proceeds of the loan. In addition, the Portfolio may be unable to sell the collateral at a time when it would be advantageous to do so, which could adversely affect the Portfolio’s strategy and result in lower returns. The Portfolio would also be subject to the risk that the lender may file for bankruptcy, become insolvent, or otherwise default on its obligations to return the collateral to the Portfolio. In the event of a default by the lender, there may be delays, costs and risks of loss involved in the Portfolio exercising its rights with respect to the collateral or those rights may be limited by other contractual agreements or obligations or by applicable law.

CUSTODIAL RECEIPTS FOR TREASURY SECURITIES. To the extent consistent with its investment objective and strategies, the Portfolio may acquire U.S. government obligations and their unmatured interest coupons that have been separated (“stripped”) by their holder, typically a custodian bank or investment brokerage firm. Having separated the interest coupons from the underlying principal of the U.S. government obligations, the holder will resell the stripped securities in custodial receipt programs with a number of different names, such as TIGRs (Treasury Income Growth Receipts) and CATS (Certificates of Accrual on Treasury Securities). The stripped coupons are sold separately from the underlying principal, which usually is sold at a deep discount because the buyer receives only the right to receive a future fixed payment on the security and does not receive any rights to periodic interest (cash) payments. The underlying U.S. Treasury bonds and notes themselves are held in book-entry form at the Federal Reserve Bank or, in the case of bearer securities (i.e., unregistered securities, which are ostensibly owned by the bearer or holder), in trust on behalf of the owners. Counsel to the underwriters of these certificates or other evidences of ownership of U.S. Treasury securities have stated that, in their opinion, purchasers of the stripped securities most likely will be deemed the beneficial holders of the underlying U.S. government obligations for federal tax purposes. The Trust is unaware of any binding legislative, judicial or administrative authority on this issue. Custodial receipts may not be considered obligations of the U.S. government or other issuer of the security held by the custodian for the purposes of securities laws. If for tax purposes the Portfolio is not considered to be the owner of the securities held in the underlying trust or custodial account, the Portfolio may suffer adverse tax consequences. As a holder of custodial receipts, the Portfolio will bear its proportionate share of the fees or expenses charged to the custodial account.

CYBERSECURITY RISK. With the increased use of technologies such as mobile devices and Web-based or “cloud” applications, and the dependence on the Internet and computer systems to conduct business, the Portfolio is susceptible to operational, information security and related risks. In general, cybersecurity incidents can result from deliberate attacks or unintentional events (arising from external or internal sources) that may cause the Portfolio to lose proprietary information, suffer data corruption, physical damage toa computer or network system or lose operational capacity. Cybersecurity attacks include, but are not limited to, infection by malicious software, such as malware or computer viruses or gaining unauthorized access to digital systems, networks or devices that are used to service the Portfolio’s operations (e.g., through “hacking,” “phishing” or malicious software coding) or other means for purposes of misappropriating assets or sensitive information, corrupting data, or causing operational disruption. Cybersecurity attacks may also be carried out in a manner that does not require gaining unauthorized access, such as causing denial-of-service attacks on the Portfolio’s websites (i.e., efforts to make network services unavailable to intended users). In addition, authorized persons could inadvertently or intentionally release confidential or proprietary information stored on the Portfolio’s systems.

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Cybersecurity incidents affecting the Investment Adviser, other service providers (including, but not limited to, the sub-administrator, custodian, sub-custodians, transfer agent and financial intermediaries) or the Portfolio’s shareholders have the ability to cause disruptions and impact business operations, potentially resulting in financial losses to both the Portfolio and shareholders, interference with the Portfolio’s ability to calculate its NAV, impediments to trading, the inability of Portfolio shareholders to transact business and the Portfolio to process transactions (including fulfillment of Portfolio share purchases and redemptions), violations of applicable privacy and other laws (including the release of private shareholder information) and attendant breach notification and credit monitoring costs, regulatory fines, penalties, litigation costs, reputational damage, reimbursement or other compensation costs, forensic investigation and remediation costs, and/or additional compliance costs. Similar adverse consequences could result from cybersecurity incidents affecting issuers of securities in which the Portfolio invests, counterparties with which the Portfolio engages in transactions, governmental and other regulatory authorities, exchange and other financial market operators, banks, brokers, dealers, insurance companies and other financial institutions (including financial intermediaries and other service providers) and other parties. In addition, substantial costs may be incurred in order to safeguard against and reduce the risk of any cybersecurity incidents in the future. In addition to administrative, technological and procedural safeguards, the Investment Adviser has established business continuity plans in the event of, and risk management systems to prevent or reduce the impact of, such cybersecurity incidents. However, there are inherent limitations in such plans and systems, including the possibility that certain risks have not been identified, as well as the rapid development of new threats. Furthermore, the Portfolio and its investment adviser have limited ability to prevent or mitigate cybersecurity incidents affecting third-party service providers, and such third-party service providers may have limited indemnification obligations to the Portfolio or its investment adviser, and the Portfolio cannot control the cybersecurity plans and systems put in place by its service providers or any other third parties whose operations may affect the Portfolio or its shareholders. The Portfolio and its shareholders could be negatively impacted as a result.

FORWARD COMMITMENTS, WHEN-ISSUED SECURITIES AND DELAYED-DELIVERY TRANSACTIONS. The Portfolio may purchase securities on a when-issued basis or purchase or sell securities on a forward commitment (sometimes called delayed-delivery) basis. These transactions involve a commitment by the Portfolio to purchase or sell securities at a future date. The price of the underlying securities (usually expressed in terms of yield) and the date when the securities will be delivered and paid for (the settlement date) are fixed at the time the transaction is negotiated. When-issued purchases and forward commitment transactions normally are negotiated directly with the other party. In addition, recently finalized rules of the Financial Industry Regulatory Authority (“FINRA”) include mandatory margin requirements that require the Portfolio to post collateral in connection with its To Be Announced (“TBA”) transactions. There is no similar requirement applicable to the Portfolio’s TBA counterparties. The required collateralization of TBA trades could increase the cost of TBA transactions to the Portfolio and impose added operational complexity.

The Portfolio will purchase securities on a when-issued basis or purchase or sell securities on a forward commitment basis only with the intention of completing the transaction and actually purchasing or selling the securities. If deemed advisable as a matter of investment strategy, however, the Portfolio may dispose of or negotiate a commitment after entering into it. The Portfolio also may sell securities it has committed to purchase before those securities are delivered to the Portfolio on the settlement date. The Portfolio may realize a capital gain or loss in connection with these transactions.

When the Portfolio purchases securities on a when-issued, delayed-delivery or forward commitment basis, the Portfolio will segregate liquid assets having a value (determined daily) at least equal to the amount of the Portfolio’s purchase commitments or will otherwise cover its position. These procedures are designed to ensure that the Portfolio will maintain sufficient assets at all times to cover its obligations under when-issued purchases, forward commitments and delayed-delivery transactions. For purposes of determining the Portfolio’s average dollar-weighted maturity, the maturity of when-issued, delayed-delivery or forward commitment securities will be calculated from the commitment date.

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ILLIQUID OR RESTRICTED INVESTMENTS. The Portfolio may invest up to 5% of its total assets in illiquid investments, as such term is defined in Rule 2a-7 under the 1940 Act. An illiquid investment is an investment that the Portfolio reasonably expects cannot be sold or disposed of in the ordinary course of business within 7 calendar days at approximately the value ascribed to it by the Portfolio. The Portfolio may purchase securities that are not registered (“restricted securities”) under the Securities Act of 1933, as amended (the “1933 Act”), including restricted securities that can be offered and sold to “qualified institutional buyers” under Rule 144A under the 1933 Act and commercial paper issued pursuant to Section 4(a)(2) of the 1933 Act. These investments will not be considered illiquid so long as the Investment Adviser determines, under guidelines approved by the Board, that an adequate trading market exists. This practice could increase the level of illiquidity during any period that qualified institutional buyers become uninterested in purchasing these investments. To the extent an investment held by the Portfolio is deemed to be an illiquid investment or a less liquid investment, the Portfolio will be exposed to a greater liquidity risk.

INFLATION-INDEXED SECURITIES. To the extent consistent with its investment objective and strategies, the Portfolio may invest in inflation-indexed securities, which are fixed-income securities whose value is periodically adjusted according to the rate of inflation. Two structures are common: the U.S. Treasury and some other issuers utilize a structure that accrues inflation into the principal value of the security; most other issuers pay out the Consumer Price Index (“CPI”) accruals as part of a semi-annual coupon.

Inflation-indexed securities issued by the U.S. Treasury have varying maturities and pay interest on a semi-annual basis equal to a fixed percentage of the inflation-adjusted principal amount. If the periodic adjustment rate measuring inflation falls, the principal value of inflation-indexed bonds will be adjusted downward, and consequently the interest payable on these securities (calculated with respect to a smaller principal amount) will be reduced. Repayment of the original bond principal upon maturity (as adjusted for inflation) is guaranteed in the case of U.S. Treasury inflation-indexed bonds, even during a period of deflation. However, the current market value of the bonds is not guaranteed and will fluctuate. If the Portfolio purchases inflation indexed securities on the secondary market whose principal values have been adjusted upward due to inflation since issuance, the Portfolio may experience a loss if there is a subsequent period of deflation. The Portfolio also may invest in other inflation-related bonds, which may or may not provide a similar guarantee. If a guarantee of principal is not provided, the adjusted principal value of the bond repaid at maturity may be less than the original principal amount.

The value of inflation-indexed bonds is expected to change in response to changes in real interest rates. Real interest rates in turn are tied to the relationship between nominal interest rates and the rate of inflation. Therefore, if the rate of inflation rises at a faster rate than nominal interest rates, real interest rates might decline, leading to an increase in value of inflation-indexed bonds. In contrast, if nominal interest rates increase at a faster rate than inflation, real interest rates might rise, leading to a decrease in value of inflation-indexed bonds. Any increase in the principal amount of an inflation-indexed bond will be considered taxable ordinary income, even though investors do not receive their principal until maturity.

While these securities are expected to be protected from long-term inflationary trends, short-term increases in inflation may lead to a decline in value. If interest rates rise due to reasons other than inflation (for example, due to changes in currency exchange rates), investors in these securities may not be protected to the extent that the increase is not reflected in the bond’s inflation measure.

The periodic adjustment of U.S. inflation-indexed bonds is tied to the Consumer Price Index for All Urban Consumers (“CPI-U”), which is calculated monthly by the U.S. Bureau of Labor Statistics. The CPI-U is a measurement of changes in the cost of living, made up of components such as housing, food, transportation and energy. Inflation-indexed bonds issued by a foreign government are generally adjusted to reflect a comparable inflation index calculated by that government. There can be no assurance that the CPI-U or any foreign inflation index will accurately measure the real rate of inflation in the prices of goods and services. Moreover, there can be no assurance that the rate of inflation in a foreign country will be correlated to the rate of inflation in the United States.

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The taxation of inflation-indexed Treasury securities is similar to the taxation of conventional bonds. Both interest payments and the difference between original principal and the inflation-adjusted principal will be treated as interest income subject to taxation. Interest payments are taxable when received or accrued. The inflation adjustment to the principal is subject to tax in the year the adjustment is made, not at maturity of the security when the cash from the repayment of principal is received. If an upward adjustment has been made (which typically should happen), investors in non-tax-deferred accounts will pay taxes on this amount currently. Decreases in the indexed principal can be deducted only from current or previous interest payments reported as income.

Inflation-indexed Treasury securities therefore have a potential cash flow mismatch to an investor, because investors must pay taxes on the inflation-adjusted principal before the repayment of principal is received. It is possible that, particularly for high income tax bracket investors, inflation-indexed Treasury securities would not generate enough income in a given year to cover the tax liability they could create. This is similar to the current tax treatment for zero-coupon bonds and other discount securities. If inflation-indexed Treasury securities are sold prior to maturity, capital losses or gains are realized in the same manner as traditional bonds. The Portfolio, however, distributes income on a monthly basis. Portfolio investors will receive dividends that represent both the interest payments and the principal adjustments of the inflation-indexed securities held in the Portfolio.

INSURANCE FUNDING AGREEMENTS. To the extent consistent with its investment objective and strategies, the Portfolio may invest in insurance funding agreements (“IFAs”). An IFA is normally a general obligation of the issuing insurance company and not a separate account. The purchase price paid for an IFA becomes part of the general assets of the insurance company, and the contract is paid from the company’s general assets. Generally, IFAs are not assignable or transferable without the permission of the issuing insurance companies, and an active secondary market in IFAs may not exist. Therefore, IFAs will be subject to the Portfolio’s limitation on illiquid investments when the Portfolio may not demand payment of the principal amount within seven days and a reliable trading market is absent.

INVESTMENT COMPANIES. With respect to the investments of the Portfolio in the securities of other affiliated and unaffiliated investment companies, such investments generally will be limited so that the Portfolio meets applicable regulatory requirements. Under Section 12(d)(1)(a) of the 1940 Act, an investment company (the “acquiring company”) acquiring securities in another investment company (the “acquired company”) must meet the following limits: (a) the acquiring company does not own more than 3% of the total outstanding voting stock of the acquired company; (b) securities issued by the acquired company have an aggregate value not in excess of 5% of the value of the total assets of the acquiring company; and (c) securities issued by the acquired company and all other investment companies (other than treasury stock of the acquiring company) do not have an aggregate value in excess of 10% of the total assets of the acquiring company. However, section 12(d)(1)(F) allows an acquiring fund to invest in excess of the 5% and 10% limits above so long as: (i) immediately after a purchase or acquisition of stock, not more than 3% of the outstanding stock of the acquired company is owned by the acquiring company and all affiliated persons of the acquiring company; and (ii) the acquiring company does not charge a sales load of more than 1 1/2%. If the Portfolio acquires shares of another investment company pursuant to Section 12(d)(1)(F), an investment company whose securities so are purchased by the Portfolio may not be obligated to redeem such securities in an amount exceeding 1% of the investment company’s total outstanding securities during any period of less than 30 days. Therefore, such securities that exceed this amount may be illiquid. Pursuant to an exemptive order, the limits will not apply to the investment of securities lending collateral by the Portfolio in certain investment portfolios advised by NTI. In addition, these limits will not apply to the investment of uninvested cash balances in shares of registered or unregistered money market portfolios whether affiliated or unaffiliated. The foregoing exemption, however, only applies to an unregistered money market portfolio that (i) limits its investments to those in which a money market portfolio may invest under Rule 2a-7 of the 1940 Act, and undertakes to comply with all the other provisions of Rule 2a-7.

Investments by the Portfolio in other investment companies, including exchange-traded funds (“ETFs”), will be subject to the limitations of the 1940 Act except as permitted by SEC orders. The Portfolio may rely on SEC

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orders that permit it to invest in certain ETFs beyond the limits contained in the 1940 Act, subject to certain terms and conditions. Generally, these terms and conditions require the Board to approve policies and procedures relating to certain of the Portfolio’s investments in ETFs. These policies and procedures require, among other things, that (i) the Investment Adviser conducts the Portfolio’s investment in ETFs without regard to any consideration received by the Portfolio or any of its affiliated persons and (ii) the Investment Adviser certifies to the Board quarterly that it has not received any consideration in connection with an investment by the Portfolio in an ETF, or if it has, the amount and purpose of the consideration will be reported to the Board and an equivalent amount of advisory fees shall be waived by the Investment Adviser.

If required by the 1940 Act, the Portfolio expects to vote the shares of other investment companies that are held by it in the same proportion as the vote of all other holders of such securities.

To the extent consistent with its investment objective and strategies, the Portfolio may invest all or substantially all of its assets in a single open-end investment company or series thereof with substantially the same investment objective, strategy and restrictions as the Portfolio. However, the Portfolio currently intends to limit its investments in securities issued by other investment companies to the extent described above. The Portfolio may adhere to other limitations with respect to its investments in securities issued by other investment companies if required or permitted by the SEC or deemed to be in the best interests of the Trust.

In October 2020, the SEC adopted certain regulatory changes and took other actions related to the ability of an investment company to invest in another investment company. These regulatory changes may adversely impact the Portfolio’s investment strategies and operations.

LARGE TRADE NOTIFICATIONS. The transfer agent may from time to time receive notice that an authorized institution or other financial intermediary has received an order for a large trade in the Portfolio’s shares. The Investment Adviser may determine to enter into portfolio transactions in anticipation of that order, even though the order will not be processed until the following business day. This practice provides for a closer correlation between the time shareholders place trade orders and the time the Portfolio enters into portfolio transactions based on those orders, and permits the Portfolio to be more fully invested in investment securities, in the case of purchase orders, and to more orderly liquidate their investment positions, in the case of redemption orders. On the other hand, the authorized institution or other financial intermediary may not ultimately process the order. In this case, the Portfolio may be required to borrow assets to settle the portfolio transactions entered into in anticipation of that order, and would therefore incur borrowing costs. The Portfolio may also suffer investment losses on those portfolio transactions. Conversely, the Portfolio would benefit from any earnings and investment gains resulting from such portfolio transactions.

LIBOR TRANSITION. Certain of the Portfolio’s investments, payment obligations and financing terms may be based on floating rates, such as London Interbank Offered Rate (“LIBOR”). On July 27, 2017, the Chief Executive of the UK Financial Conduct Authority (“FCA”), which regulates LIBOR, announced a desire to phase out the use of LIBOR by the end of 2021. Although many LIBOR rates will be phased out at the end of 2021 as originally intended, a selection of widely used USD LIBOR rates will continue to be published until June 2023 in order to assist with the transition. There remains uncertainty regarding the effect of the LIBOR transition process and therefore any impact of a transition away from LIBOR on the instruments in which the Portfolio invests cannot yet be determined. There is no assurance that the composition or characteristics of any alternative reference rate will be similar to or produce the same value or economic equivalence as LIBOR or that instruments using an alternative rate will have the same volume or liquidity. This announcement and any additional regulatory or market changes that occur as a result of the transition away from LIBOR and the adoption of alternative reference rates may have an adverse impact on the value of the Portfolio’s investments, performance or financial condition, and might lead to increased volatility and illiquidity in markets that currently rely on LIBOR to determine interest rates.

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LIQUIDITY RISK. Liquidity risk is the risk that the Portfolio will not be able to pay redemption proceeds within the time periods described in a timely manner because of unusual market conditions, an unusually high volume of redemption requests, legal restrictions impairing the Portfolio’s ability to sell particular securities or close out derivative positions at an advantageous market price or other reasons. Certain portfolio securities may be less liquid than others, which may make them difficult or impossible to sell at the time and the price that the Portfolio would like or difficult to value. The Portfolio may have to lower the price, sell other securities instead or forgo an investment opportunity. In addition, less liquid securities may be more difficult to value and markets may become less liquid when there are fewer interested buyers or sellers or when dealers are unwilling or unable to make a market for certain securities. For the same reason, less liquid securities that the Portfolio may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Portfolio’s ability to buy or sell such securities. All of these risks may increase during periods of market turmoil and could have a negative effect on portfolio management or performance. Liquidity risk may be the result of, among other things, the reduced number and capacity of traditional market participants to make a market in fixed income securities. The potential for liquidity risk may be magnified by a rising interest rate environment or other circumstances where investor redemptions from money market and other fixed income mutual funds may be higher than normal, potentially causing increased supply in the market due to selling activity. All of these risks may increase during periods of market volatility. The liquidity of certain assets, such as privately issued and non-investment grade mortgage- and asset-backed securities, may be difficult to ascertain and may change over time. Transactions in less liquid securities may entail transaction costs that are higher than those for transactions in more liquid securities.

NEGATIVE INTEREST RATES. Interest rates in the United States are currently at historically low levels. During periods when interest rates are low (or negative), the Portfolio’s yield (or total return) may also be low and fall below zero. Very low or negative interest rates may magnify interest rate risk. Changing interest rates, including rates that fall below zero, may have unpredictable effects on markets, may result in heightened market volatility and may detract from the Portfolio’s performance to the extent the Portfolio is exposed to such interest rates and/or volatility. A negative interest rate policy is an unconventional central bank monetary policy tool where nominal target interest rates are set with negative value intended to help create self-sustaining growth in the local economy. To the extent the Portfolio holds a debt instrument with a negative interest rate, the Portfolio would generate a negative return on that investment. If negative interest rates become more prevalent in the market, investors may seek to reallocate their investment to other income-producing assets, which could further reduce the value of instruments with a negative yield.

A low or negative interest rate environment could impact the Portfolio’s ability to maintain a stable $1.00 share price. During a low or negative interest rate environment, the Portfolio may reduce the number of shares outstanding on a pro rata basis through reverse stock splits, negative dividends or other mechanisms to seek to maintain a stable $1.00 price per share, to the extent permissible by applicable law and its organizational documents. Alternatively, the Portfolio may discontinue using the amortized cost method of valuation to maintain a stable $1.00 price per share and establish a fluctuating NAV per share rounded to four decimal places by using available market quotations or equivalents.

OPERATIONAL RISK. The Investment Adviser and other Portfolio service providers may experience disruptions or operating errors arising from factors such as processing errors, inadequate or failed internal or external processes, failures in systems and technology, changes in personnel, and errors caused by third-party service providers or trading counterparties. In particular, these errors or failures in systems and technology, including operational risks associated with reliance on third party service providers, may affect the Portfolio’s ability to calculate its NAV in a timely manner, including over a potentially extended period. Moreover, disruptions (for example, pandemics and health crises) that cause prolonged periods of remote work or significant employee absences at the Portfolio’s service providers could impact the ability to conduct the Portfolio’s operations. While service providers are required to have appropriate operational risk management policies and procedures, their methods of operational risk management may differ from those of the Portfolio in the setting of priorities, the personnel and resources available or the effectiveness of relevant controls. The

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Investment Adviser, through its monitoring and oversight of service providers, seeks to ensure that service providers take appropriate precautions to avoid and mitigate risks that could lead to disruptions and operating errors. However, it is not possible for the Investment Adviser or other Portfolio service providers to identify all of the operational risks that may affect the Portfolio or to develop processes and controls to completely eliminate or mitigate their occurrence or effects.

QUALIFIED FINANCIAL CONTRACTS. Regulations adopted by federal banking regulators under the Dodd-Frank Wall Street Reform and Consumer Protection Act (“Dodd-Frank”), which took effect in 2019, require that certain qualified financial contracts (“QFCs”) with counterparties that are part of U.S. or foreign global systemically important banking organizations be amended to include contractual restrictions on close-out and cross-default rights. QFCs include, but are not limited to, securities contracts, commodities contracts, forward contracts, repurchase agreements, securities lending agreements and swaps agreements, as well as related master agreements, security agreements, credit enhancements, and reimbursement obligations. If a covered counterparty of the Portfolio or certain of the covered counterparty’s affiliates were to become subject to certain insolvency proceedings, the Portfolio may be temporarily unable to exercise certain default rights, and the QFC may be transferred to another entity. These requirements may impact the Portfolio’s credit and counterparty risks.

REPURCHASE AGREEMENTS. To the extent consistent with its investment objective and strategies, the Portfolio may agree to purchase portfolio securities from domestic and foreign financial institutions subject to the seller’s agreement to repurchase them at a mutually agreed upon date and price (“repurchase agreements”). Repurchase agreements may be considered to be loans under the 1940 Act. Although the securities subject to a repurchase agreement may bear maturities exceeding one year, settlement for the repurchase agreement generally will not be more than one year after the Portfolio’s acquisition of the securities and normally will be within a shorter period of time. Securities subject to repurchase agreements normally are held either by the Trust’s custodian or subcustodian (if any), or in the Federal Reserve/Treasury Book-Entry System.

The Portfolio may permit the seller’s obligation to be novated to the Fixed Income Clearing Corporation (“FICC”) pursuant to an agreement among the Portfolio, FICC and the seller as a sponsoring member of FICC. In such case, the FICC would become the Portfolio’s counterparty. The Portfolio will make payment for such securities only upon physical delivery or evidence of book-entry transfer to the account of the sponsoring member, the custodian or a bank acting as agent for the Portfolio. The Portfolio would become subject to the FICC’s rules, which may limit the Portfolio’s rights and remedies (including recourse to collateral) or delay or restrict the rights and remedies, and expose the Portfolio to the risk of FICC’s insolvency.

The seller under a repurchase agreement will be required to maintain the value of the securities subject to the agreement in an amount exceeding the repurchase price (including accrued interest). Default by the seller or FICC would, however, expose the Portfolio to possible loss because of adverse market action or delay in connection with the disposition of the underlying obligations. In addition, in the event of a bankruptcy, the Portfolio could suffer additional losses if a court determines that the Portfolio’s interest in the collateral is unenforceable. If the Portfolio enters into a repurchase agreement involving securities the Portfolio could not purchase directly, and the counterparty defaults, the Portfolio may become the holder of securities that it could not purchase. Apart from the risks associated with bankruptcy or insolvency proceedings, there is also the risk that the seller or FICC may fail to repurchase the security. If the market value of the securities subject to the repurchase agreement becomes less than the repurchase price (including accrued interest), generally, the seller of the securities or FICC will be required to deliver additional securities so that the market value of all securities subject to the repurchase agreement equals or exceeds the repurchase price. Repurchase agreements may be subject to additional regulation as qualified financial contracts (see “Qualified Financial Contracts above for additional information).

In the event of default by a foreign counterparty in a repurchase agreement, the Portfolio may be unable to successfully assert a claim to the collateral under foreign laws. As a result, repurchase agreements with a foreign

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financial institution may involve higher credit risks than repurchase agreements with domestic financial institutions. Moreover, certain foreign countries may have less developed and less regulated banking systems and auditing, accounting and financial reporting systems than the United States. In addition, repurchase agreements with foreign financial institutions located in emerging markets, or relating to emerging markets, may involve foreign financial institutions or counterparties with lower credit ratings than domestic financial institutions.

Pursuant to exemptive relief granted by the SEC, and to the extent consistent with its investment objective and strategies, the Portfolio, and certain other money market portfolios advised by NTI and TNTC, may enter into joint repurchase agreements with non-affiliated counterparties through a master repurchase agreement. NTI administers and manages these joint repurchase agreements in accordance with and as part of its duties under its management agreement with the Portfolio and does not collect any additional fees from the Portfolio for such services.

REVERSE REPURCHASE AGREEMENTS. The Portfolio may borrow funds by selling portfolio securities to financial institutions such as banks and broker/dealers and agreeing to repurchase them at a mutually specified date and price (“reverse repurchase agreements”). The Portfolio may use the proceeds of reverse repurchase agreements to purchase other securities either maturing, or under an agreement to resell, on a date simultaneous with or prior to the expiration of the reverse repurchase agreement. Reverse repurchase agreements are considered to be borrowings under the 1940 Act. The use of reverse repurchase agreements may be regarded as leveraging and, therefore, speculative. Furthermore, reverse repurchase agreements involve the risks that (i) the interest income earned in the investment of the proceeds will be less than the interest expense, (ii) the market value of the securities retained in lieu of sale by the Portfolio may decline below the price of the securities the Portfolio has sold but are obligated to repurchase, (iii) the market value of the securities sold will decline below the price at which the Portfolio is required to repurchase them and (iv) the securities will not be returned to the Portfolio. The Portfolio will pay interest on amounts obtained pursuant to a reverse repurchase agreement. While reverse repurchase agreements are outstanding, the Portfolio will segregate liquid assets in an amount at least equal to the market value of the securities, plus accrued interest, subject to the agreement.

In addition, if the buyer of securities under a reverse repurchase agreement files for bankruptcy or becomes insolvent, such buyer or its trustee or receiver may receive an extension of time to determine whether to enforce the Portfolio’s obligations to repurchase the securities and the Portfolio’s use of the proceeds of the reverse repurchase agreement may effectively be restricted pending such decision. Reverse repurchase agreements may be subject to additional regulation as qualified financial contracts (see “Qualified Financial Contracts above for additional information).

STRIPPED SECURITIES. To the extent consistent with its investment objective and strategies, the Portfolio may purchase stripped securities. The Treasury Department has facilitated transfers of ownership of zero coupon securities by accounting separately for the beneficial ownership of particular interest coupon and principal payments on Treasury securities through the Federal Reserve book-entry record-keeping system. The Federal Reserve program as established by the Treasury Department is known as “Separate Trading of Registered Interest and Principal of Securities” or “STRIPS.” The Portfolio may purchase securities registered in the STRIPS program. Under the STRIPS program, the Portfolio will be able to have its beneficial ownership of zero coupon securities recorded directly in the book-entry record-keeping system in lieu of having to hold certificates or other evidences of ownership of the underlying U.S. Treasury securities.

Other types of stripped securities may be purchased by the Portfolio, including stripped mortgage-backed securities (“SMBS”). SMBS usually are structured with two or more classes that receive different proportions of the interest and principal distributions from a pool of mortgage-backed obligations. A common type of SMBS will have one class receiving all of the interest, while the other class receives all of the principal. However, in some instances, one class will receive some of the interest and most of the principal while the other class will receive most of the interest and the remainder of the principal. If the underlying obligations experience greater than anticipated prepayments of principal, the Portfolio may fail to recoup fully its initial investment in these

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securities. The market value of the class consisting entirely of principal payments generally is extremely volatile in response to changes in interest rates. The yields on a class of SMBS that receives all or most of the interest generally are higher than prevailing market yields on other mortgage-backed obligations because their cash flow patterns also are volatile and there is a risk that the initial investment will not be recouped fully. SMBS issued by the U.S. government (or a U.S. government agency, instrumentality or sponsored enterprise) may be considered liquid under guidelines established by the Board if they can be disposed of promptly in the ordinary course of business at a value reasonably close to that used in the calculation of the NAV per share.

STRUCTURED SECURITIES. To the extent consistent with its investment objective and strategies, the Portfolio may purchase structured securities. These fixed-income instruments are structured to recast the investment characteristics of the underlying security or reference asset. If the issuer is a unit investment trust or other special purpose vehicle, the structuring will typically involve the deposit with or purchase by such issuer of specified instruments (such as commercial bank loans or securities) and/or the execution of various derivative transactions, and the issuance by that entity of one or more classes of securities (structured securities) backed by, or representing interests in, the underlying instruments. The cash flow on the underlying instruments may be apportioned among the newly issued structured securities to create securities with different investment characteristics, such as varying maturities, payment priorities and interest rate provisions, and the extent of such payments made with respect to structured securities is dependent on the extent of the cash flow on the underlying instruments. Investments in these securities may be structured as a class that is either subordinated or unsubordinated to the right of payment of another class. Subordinated structured securities typically have higher rates of return and present greater risks than unsubordinated structured products.

The Portfolio’s investments in these instruments are indirectly subject to the risks associated with derivative instruments, including, among others, credit risk, default or similar event risk, counterparty risk, interest rate risk, leverage risk and management risk. Because structured securities typically involve no credit enhancement, their credit risk generally will be equivalent to that of the underlying instruments. These securities generally are exempt from registration under the 1933 Act. Accordingly, there may be no established trading market for the securities and they may constitute illiquid investments. Structured securities may entail a greater degree of market risk than other types of debt securities because the investor bears the risk of the underlying security or reference asset. Structured securities may also be more volatile, less liquid, and more difficult to price accurately than less complex securities or more traditional debt securities.

TRADING RISK. In order to engage in certain transactions on behalf of the Portfolio, the Investment Adviser will be subject to (or cause the Portfolio to become subject to) the rules, terms and/or conditions of any venues through which it trades securities, derivatives or other instruments. This includes, but is not limited to, where the Investment Adviser and/or the Portfolio may be required to comply with the rules of certain exchanges, execution platforms, trading facilities, clearinghouses and other venues, or may be required to consent to the jurisdiction of any such venues. The rules, terms and/or conditions of any such venue may result in the Investment Adviser (and/or the Portfolio) being subject to, among other things, margin requirements, additional fees and other charges, disciplinary procedures, reporting and recordkeeping, position limits and other restrictions on trading, settlement risks and other related conditions on trading set out by such venues.

U.S. GOVERNMENT OBLIGATIONS. Examples of the types of U.S. government obligations that may be acquired by the Portfolio include U.S. Treasury Bills, Treasury Notes and Treasury Bonds. The Portfolio also may acquire obligations of Federal Home Loan Banks, Federal Farm Credit Banks, Federal Land Banks, the Federal Housing Administration, Farmers Home Administration, Export-Import Bank of the United States, Small Business Administration, Fannie Mae, Ginnie Mae, General Services Administration, Central Bank for Cooperatives, Freddie Mac, Federal Intermediate Credit Banks and the Maritime Administration.

Securities guaranteed as to principal and interest by the U.S. government or by its agencies, instrumentalities or sponsored enterprises also are deemed to include (i) securities for which the payment of

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principal and interest is backed by an irrevocable letter of credit issued by the U.S. government or by any agency, instrumentality or sponsored enterprise thereof, and (ii) participations in loans made to foreign governments or their agencies that are so guaranteed.

To the extent consistent with its investment objective and strategies, the Portfolio may invest in a variety of U.S. Treasury obligations and obligations issued by or guaranteed by the U.S. government or by its agencies, instrumentalities or sponsored enterprises. Not all U.S. government obligations carry the same credit support. No assurance can be given that the U.S. government would provide financial support to its agencies, instrumentalities or sponsored enterprises if it were not obligated to do so by law. There is no assurance that these commitments will be undertaken or complied with in the future. 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. In addition, the secondary market for certain participations in loans made to foreign governments or their agencies may be limited. In the absence of a suitable secondary market, such participations are generally considered illiquid.

Many states grant tax-free status to dividends paid to shareholders of a fund from interest income earned by that fund from direct obligations of the U.S. government, subject in some states to minimum investment requirements that must be met by the fund. Investments in securities issued by Ginnie Mae or Fannie Mae, bankers’ acceptances, commercial paper and repurchase agreements collateralized by U.S. government securities do not generally qualify for tax-free treatment.

VARIABLE AND FLOATING RATE INSTRUMENTS. Variable and floating rate instruments have interest rates that periodically are adjusted either at set intervals or that float at a margin in relation to a generally recognized index rate. These instruments include long-term floating rate public obligations of the U.S. Treasury and variable and floating rate bonds (sometimes referred to as “put bonds”) where the Portfolio obtains at the time of purchase the right to put the bond back to the issuer or a third party at par at a specified date and also includes leveraged inverse floating rate instruments (“inverse floaters”).

With respect to the variable and floating rate instruments that may be acquired by the Portfolio, the Investment Adviser will consider the earning power, cash flows and other liquidity ratios of the issuers and guarantors of such instruments and, if the instruments are subject to demand features, will monitor their financial status and ability to meet payment on demand. Where necessary to ensure that a variable or floating rate instrument meets the Portfolio’s quality requirements, the issuer’s obligation to pay the principal of the instrument will be backed by an unconditional bank letter or line of credit, guarantee or commitment to lend.

The Portfolio will invest in variable and floating rate instruments only when the Investment Adviser deems the investment to involve minimal credit risk. Unrated variable and floating rate instruments will be determined by the Investment Adviser to be of comparable quality at the time of the purchase to rated instruments that may be purchased by the Portfolio. In determining weighted average portfolio maturity, an instrument may, subject to the SEC’s regulations, be deemed to have a maturity shorter than its nominal maturity based on the period remaining until the next interest rate adjustment or the time the Portfolio involved can recover payment of principal as specified in the instrument. In determining weighted average life under Rule 2a-7(d)(1)(iii) (“WAL”), a floating rate instrument shall be deemed to have a maturity equal to the period remaining until the principal amount can be recovered through demand.

Variable and floating rate instruments that may be purchased by the Portfolio include variable amount master demand notes, which permit the indebtedness thereunder to vary in addition to providing for periodic adjustments in the interest rate. Variable and floating rate instruments held by the Portfolio will be subject to the Portfolio’s limitation on illiquid investments, absent a reliable trading market, when the Portfolio may not demand payment of the principal amount within seven days. Because there is no active secondary market for

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certain variable and floating rate instruments, they may be more difficult to sell if the issuer defaults on its payment obligations or during periods when the Portfolio is not entitled to exercise its demand rights. As a result, the Portfolio could suffer a loss with respect to these instruments.

Floating rate instruments are subject to the risks under “LIBOR Transition” above.

YIELDS AND RATINGS. The yields on certain obligations, including the instruments in which the Portfolio may invest, are dependent on a variety of factors, including general market conditions, conditions in the particular market for the obligation, financial condition of the issuer, size of the offering, maturity of the obligation and ratings of the issue. The ratings of S&P Global Ratings (“S&P”), DBRS Morningstar Ratings Limited (“DBRS”), Moody’s Investors Service, Inc. (“Moody’s”) and Fitch Ratings (“Fitch”) represent their respective opinions as to the quality of the obligations they undertake to rate. Ratings, however, are general and are not absolute standards of quality. Consequently, obligations with the same rating, maturity and interest rate may have different market prices. For a more complete discussion of ratings, see Appendix A to this SAI.

Subject to the limitations stated in the Prospectus, if a security held by the Portfolio undergoes a rating revision, the Portfolio may continue to hold the security if the Investment Adviser determines such retention is warranted.

INVESTMENT RESTRICTIONS

The Portfolio is subject to the fundamental investment restrictions enumerated below, which may be changed with respect to the particular Portfolio only by a vote of the holders of a majority of the Portfolio’s outstanding shares as described in “Description of Shares” beginning on page 52.

The Portfolio may not:

(1) Make loans, except through (a) the purchase of debt obligations in accordance with the Portfolio’s investment objective and strategies, (b) repurchase agreements with banks, brokers, dealers and other financial institutions, (c) loans of securities, and (d) loans to affiliates of the Portfolio to the extent permitted by law.

(2) Purchase or sell real estate or securities issued by real estate investment trusts (“REITs”) but this restriction shall not prevent a Portfolio from investing directly or indirectly in portfolio instruments secured by real estate or interests therein.

(3) Invest in commodities or commodity contracts, except to the extent permitted under the 1940 Act, the rules and regulations thereunder or any exemptions therefrom, as such statute, rules or regulations may be amended or interpreted from time to time, and the Portfolio may invest in currency and financial instruments and contracts that are commodities or commodity contracts.

(4) Invest in companies for the purpose of exercising control or management.

(5) Act as underwriter of securities, except as the Portfolio may be deemed to be an underwriter under the 1933 Act in connection with the purchase and sale of portfolio instruments in accordance with its investment objective and portfolio management policies.

(6) Make any investment inconsistent with the Portfolio’s classification as a diversified investment company under the 1940 Act.

(7) Purchase securities if such purchase would cause more than 25% in the aggregate of the market value of the total assets of a Portfolio to be invested in the securities of one or more issuers having their principal business activities in the same industry, provided that there is no limitation with respect to, and the Portfolio reserves freedom of action, when otherwise consistent with its investment strategies, to concentrate its investments in obligations issued or guaranteed by the U.S. government, its agencies or

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instrumentalities, obligations (other than commercial paper) issued or guaranteed by U.S. banks and U.S. branches of foreign banks and repurchase agreements and securities loans collateralized by such U.S. government obligations or such bank obligations. For the purpose of this restriction, state and municipal governments and their agencies and authorities are not deemed to be industries; as to utility companies, the gas, electric, water and telephone businesses are considered separate industries; personal credit finance companies and business credit finance companies are deemed to be separate industries; and wholly-owned finance companies are considered to be in the industries of their parents if their activities are primarily related to financing the activities of their parents.

(8) Borrow money, except that to the extent permitted by applicable law (a) the Portfolio may borrow from banks, other affiliated investment companies and other persons, and may engage in reverse repurchase agreements and other transactions which involve borrowings, in amounts up to 33-1/3% of its total assets (including the amount borrowed) or such other percentage permitted by law, (b) the Portfolio may borrow up to an additional 5% of its total assets for temporary purposes, (c) the Portfolio may obtain such short-term credits as may be necessary for the clearance of purchases and sales of portfolio securities, and (d) the Portfolio may purchase securities on margin. If due to market fluctuations or other reasons the Portfolio’s borrowings exceed the limitations stated above, the Trust will promptly reduce the borrowings of such Portfolio in accordance with the 1940 Act. In addition, as a matter of fundamental policy, the Portfolio will not issue senior securities to the extent such issuance would violate applicable law.

(9) Notwithstanding any of the Trust’s other fundamental investment restrictions (including, without limitation, those restrictions relating to issuer diversification, industry concentration and control), the Portfolio may: (a) purchase securities of other investment companies to the full extent permitted under Section 12 or any other provision of the 1940 Act (or any successor provision thereto) or under any regulation or order of the SEC; and (b) invest all or substantially all of its assets in a single open-end investment company or series thereof with substantially the same investment objective, strategies and fundamental restrictions as the Portfolio.

For the purposes of Investment Restriction Nos. 1 and 8 above, the Portfolio has received an exemptive order from the SEC permitting them to participate in lending and borrowing arrangements with affiliates.

In applying Investment Restriction No. 6 above, a security is considered to be issued by the entity, or entities, whose assets and revenues back the security. A guarantee of a security is not deemed to be a security issued by the guarantor when the value of all securities issued and guaranteed by the guarantor, and owned by the Portfolio, does not exceed 10% of the value of the Portfolio’s total assets.

The freedom of action reserved in Investment Restriction No. 7 with respect to U.S. branches of foreign banks is subject to the requirement that they are subject to the same regulation as domestic branches of U.S. banks. The freedom of action reserved with respect to foreign branches of U.S. banks is subject to the requirement that the U.S. parent of the foreign branch be unconditionally liable in the event that the foreign branch failed to pay on its instruments for any reason. Obligations of U.S. branches of foreign banks may include certificates of deposit, bank and deposit notes, bankers’ acceptances and fixed time deposits. These obligations may be general obligations of the parent bank or may be limited to the issuing branch. Such obligations will meet the criteria for “Eligible Securities” as defined by the SEC under Rule 2a-7 of the 1940 Act.

Except to the extent otherwise provided in Investment Restriction No. 7, for the purpose of such restriction in determining industry classification, the Portfolio may use the industry classification provided by a third-party service provider. For the purpose of determining the percentage of the Portfolio’s total assets invested in securities of issuers having their principal business activities in a particular industry, an asset-backed security will be classified separately based on the nature of its underlying assets.

Securities held in escrow or separate accounts in connection with the Portfolio’s investment practices as described in this SAI and the Prospectus are not deemed to be mortgaged, pledged or hypothecated for purposes of the foregoing restrictions.

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Notwithstanding Investment Restriction No. 8, the Portfolio intends, as a non-fundamental policy, to limit all borrowings to no more than 25% of its total assets (including the amount borrowed).

The Portfolio may follow non-fundamental operational policies that are more restrictive than its fundamental investment limitations, as set forth in the Prospectus and this SAI, in order to comply with applicable laws and regulations, including the provisions of and regulations under the 1940 Act. In particular, the Portfolio intends to comply with the various requirements of Rule 2a-7 under the 1940 Act, as applicable, which regulates money market mutual funds, including the diversification requirements of Rule 2a-7. The Portfolio may change these operational policies to reflect changes in the laws and regulations without the approval of its shareholders.

The Portfolio intends, as a non-fundamental policy, to diversify its investments in accordance with current SEC regulations. Investments in securities (excluding cash, cash items, certain repurchase agreements, U.S. government securities and securities of other investment companies that are money market funds) will be limited to: (1) not more than 5% of the value of the Portfolio’s total assets at the time of purchase of any single issuer (and certain affiliates of that issuer), except that 25% of the value of the total assets of the Portfolio may be invested in the securities of any one issuer for a period of up to three Business Days; and (2) not more than 10% of the value of the Portfolio’s total assets at the time of purchase in the securities subject to demand features or guarantees from an institution. For the Portfolio, subject to certain exceptions, immediately after the acquisition of any demand features or guarantees (i.e., generally, the right to sell the security at a price equal to its approximate amortized cost (for a demand feature) or principal amount (for a guarantee) plus accrued interest), no more than 10% of the Portfolio’s total assets may be invested in securities issued by or subject to demand features or guarantees issued by the same issuer. Certain affiliated issuers will be treated as a single issuer for purposes of these requirements. Rule 2a-7 under the 1940 Act requires money market funds to purchase securities that have a remaining maturity of no more than 397 calendar days (unless otherwise permitted under Rule 2a-7) and (i) which have been determined by a money market fund’s board of trustees (or the fund’s investment adviser, if the board of trustees delegates such power to the adviser) to present minimal credit risks to the fund; or (ii) are issued by other investment companies that are money market funds; or (iii) are U.S. government securities. NTI considers several factors, including the capacity of each security’s issuer or guarantor to meet its financial obligations. Securities in which the Portfolio may invest may not earn as high a level of income as long-term or lower quality securities, which generally have greater market risk and more fluctuation in market value.

The following descriptions from the 1940 Act may assist shareholders in understanding the above policies and restrictions.

Concentration and Industry Classification. The SEC has presently defined concentration as investing 25% or more of an investment company’s net assets in an industry or group of industries, with certain exceptions. In determining industry classification, the Portfolio may use the industry classification provided by a third party service provider. For the purpose of determining the percentage of the Portfolio’s total assets invested in securities of issuers having their principal business activities in a particular industry, (i) an asset-backed security will be classified separately based on the nature of its underlying assets; (ii) state and municipal governments and their agencies and authorities are not deemed to be industries; (iii) as to utility companies, the gas, electric, water and telephone businesses are considered separate industries; (iv) personal credit finance companies and business credit finance companies are deemed to be separate industries; and (v) wholly-owned financial companies are considered to be in the industries of their parents if their activities are primarily related to financing the activities of their parents.

Borrowing. The 1940 Act presently allows the Portfolio to borrow from any bank (including pledging, mortgaging or hypothecating assets) in an amount up to 33-1/3% of its total assets, including the amount borrowed (not including temporary borrowings not in excess of 5% of its total assets).

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Senior Securities. Senior securities may include any obligation or instrument issued by a fund evidencing indebtedness. The 1940 Act generally prohibits funds from issuing senior securities, although it does not treat certain transactions as senior securities, such as certain borrowings, short sales, reverse repurchase agreements, firm commitment agreements and standby commitments, with appropriate earmarking or segregation of assets to cover such obligation.

Lending. Under the 1940 Act, the Portfolio may only make loans if expressly permitted by its investment policies. The Portfolio’s non-fundamental investment policy on lending is set forth above.

Underwriting. Under the 1940 Act, underwriting securities involves the Portfolio purchasing securities directly from an issuer for the purpose of selling (distributing) them or participating in any such activity either directly or indirectly. Under the 1940 Act, a diversified Portfolio may not make any commitment as underwriter, if immediately thereafter the amount of its outstanding underwriting commitments, plus the value of its investments in securities of issuers (other than investment companies) of which it owns more than 10% of the outstanding voting securities, exceeds 25% of the value of its total assets.

Real Estate. The 1940 Act does not directly restrict the Portfolio’s ability to invest in real estate, but does require that every Portfolio have a fundamental investment policy governing such investments. The Portfolio has adopted a fundamental policy that would prohibit direct investment in real estate or securities issued by REITs. However, the Portfolio is permitted to invest directly or indirectly in portfolio instruments secured by real estate or interests therein.

Securities held in escrow or separate accounts in connection with the Portfolio’s investment practices described in this SAI and the Prospectus are not deemed to be mortgaged, pledged or hypothecated for purposes of the foregoing restrictions.

Any Investment Restriction which involves a maximum percentage (other than the restriction set forth above with respect to borrowing money) will not be considered violated unless an excess over the percentage occurs immediately after, and is caused by, an acquisition or encumbrance of securities or assets of, or borrowings by, the Portfolio. The 1940 Act requires that if the asset coverage for borrowings at any time falls below 33-1/3% of its total assets including the amount borrowed) plus an additional 5% of its total assets for temporary purposes, the Portfolio will, within three days thereafter (not including Sundays and holidays), reduce the amount of its borrowings to an extent that the net asset coverage of such borrowings shall conform to such limits. As of the date of this SAI, the Portfolio does not engage in securities lending.

Although the foregoing Investment Restrictions would permit the Portfolio to acquire options, enter into forward currency contracts and engage in short sales and interest rate and currency swaps, they are not currently permitted to engage in these transactions under SEC regulations.

DISCLOSURE OF PORTFOLIO HOLDINGS

The Board has adopted a policy on disclosure of portfolio holdings, which it believes is in the best interest of the Portfolio’s shareholders. The policy provides that neither the Portfolio nor their Investment Adviser, Distributor or any agent, or any employee thereof (“Portfolio Representative”) will disclose the Portfolio’s portfolio holdings information to any person other than in accordance with the policy. For purposes of the policy, “portfolio holdings information” means the Portfolio’s actual portfolio holdings, as well as non-public information about its trading strategies or pending transactions including the portfolio holdings, trading strategies or pending transactions of any actively managed commingled fund portfolio which contains identical holdings as the Portfolio. Under the policy, neither the Portfolio nor any Portfolio Representative may solicit or accept any compensation or other consideration in connection with the disclosure of portfolio holdings information. The Portfolio Representative may provide portfolio holdings information to third parties if such information has been included in the Portfolio’s public filings with the SEC or is disclosed on the Trust’s publicly accessible website. Information posted on the Trust’s website may be separately provided to any person commencing the day after it is first published on the Trust’s website.

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Portfolio holdings information that is not filed with the SEC or posted on the publicly available website may be provided to third parties only if the third party recipients are required to keep all portfolio holdings information confidential and are prohibited from trading on the information they receive. Disclosure to such third parties must be approved in advance by the Trust’s Chief Compliance Officer (“CCO”). Disclosure to providers of auditing, custody, proxy voting and other similar services for the Portfolio, as well as rating and ranking organizations, will generally be permitted; however, information may be disclosed to other third parties (including, without limitation, individuals, institutional investors, and intermediaries that sell shares of the Portfolio) only upon approval by the CCO, who must first determine that the Portfolio has a legitimate business purpose for doing so. In general, each recipient of non-public portfolio holdings information must sign a confidentiality and non-trading agreement, although this requirement will not apply when the recipient is otherwise subject to a duty of confidentiality as determined by the CCO. In accordance with the policy, the recipients who receive non-public portfolio holdings information on an ongoing basis are as follows: the Investment Adviser and its affiliates, the Portfolio’s independent registered public accounting firm, the Portfolio’s custodian, the Portfolio’s legal counsel, the Portfolio’s financial printer (Donnelley Financial Solutions), the Portfolio’s pricing vendors, and the Portfolio’s proxy voting service and subsidiary (Institutional Shareholder Services, Inc. and Securities Class Action Service, LLC); certain industry reporting providers (iMoneyNet); certain rating and ranking organizations, including Moody’s, Fitch and S&P; and the following vendors that provide portfolio analytical tools: Barclays Capital, BlackRock Solutions, Bloomberg, FactSet, and Thomson Reuters. These entities are obligated to keep such information confidential. Third-party providers of custodial or accounting services to the Portfolio may release non-public portfolio holdings information of the Portfolio only with the permission of Portfolio Representatives. From time to time, portfolio holdings information may be provided to broker-dealers solely in connection with the Portfolio seeking portfolio securities trading recommendations. Portfolio holdings information may also be provided to financial institutions solely for the purpose of funding borrowings under the Trust’s line of credit. In providing this information, reasonable precautions, including limitations on the scope of the portfolio holdings information disclosed, are taken in an effort to avoid any potential misuse of the disclosed information.

The Portfolio currently publishes on the Trust’s website, northerntrust.com/institutional, no later than the fifth business day of each month and for a period of not less than six months, a complete schedule of the Portfolio’s holdings and certain other information required by Rule 2a-7 regarding the Portfolio’s portfolio holdings as of the last business day of the prior month. The Portfolio may publish on the website complete portfolio holdings information more frequently if it has a legitimate business purpose for doing so.

Portfolio holdings for the Portfolio is currently disclosed through required filings with the SEC. The Portfolio files its portfolio holdings with the SEC and the holdings are publicly made available twice each fiscal year on Form N-CSR (with respect to each annual period and semiannual period). Certain information with respect to the Portfolio will be provided in monthly holdings reports to the SEC on Form N-MFP2. Form N-MFP2 will be made available to the public on the SEC’s EDGAR database immediately upon filing after the end of the month to which the information pertains, and a link to each of the most recent 12 months of filings on Form N-MFP2 will be provided on the Trust’s website. In addition, in the event that the Portfolio file information regarding certain material events with the SEC on Form N-CR, the Portfolio will disclose on their website certain information that the Portfolio is required to report on Form N-CR. Such material events include the provision of any financial support by an affiliated person of the Portfolio or a decline in weekly liquid assets below 10% of the Portfolio’s total assets. This information will appear on the Portfolio’s website no later than the same business day on which the Portfolio files Form N-CR with the SEC and will be available on the Portfolio’s website for at least one year. Shareholders may obtain the Portfolio’s Forms N-CSR, N-MFP2 and N-CR filings on the SEC’s website at sec.gov.

Under the policy, the Board is to receive information, on a quarterly basis, regarding any other disclosures of non-public portfolio holdings information that were permitted during the preceding quarter.

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ADDITIONAL TRUST INFORMATION

TRUSTEES AND OFFICERS

The Board is responsible for the management and business and affairs of the Trust. Set forth below is information about the Trustees and the Officers of Northern Institutional Funds as of the date of this SAI. Each Trustee has served in that capacity since he or she was originally elected or appointed to the Board. As of the date of this SAI, each Trustee oversees a total of 46 portfolios in the Northern Funds Complex—Northern Institutional Funds consists of 5 portfolios and Northern Funds offers 41 portfolios.

NON-INTERESTED TRUSTEES

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NON-INTERESTED TRUSTEES (CONTINUED)

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NON-INTERESTED TRUSTEES (CONTINUED)

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NON-INTERESTED TRUSTEES (CONTINUED)

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INTERESTED TRUSTEE

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OFFICERS OF THE TRUST

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OFFICERS OF THE TRUST (CONTINUED)

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As a result of the responsibilities assumed by the Trust’s service providers, the Trust itself requires no employees.

Each officer holds comparable positions with Northern Funds and certain officers hold comparable positions with certain other investment companies of which Northern Trust Corporation, or an affiliate thereof, is the investment adviser, custodian, transfer agent and/or administrator.

LEADERSHIP STRUCTURE. The Board is currently composed of eight Trustees, seven of whom are not “interested persons” as defined in the 1940 Act (“non-interested Trustee”), and one of whom is an “interested person” as defined in the 1940 Act (“interested Trustee”). The Chairperson of the Board, Thomas A. Kloet, is a non-interested Trustee. Darek Wojnar is considered an interested Trustee because he is an officer, director, employee, and a shareholder of Northern Trust Corporation and/or its affiliates. Each Trustee was nominated to serve on the Board because of his or her experience, skills and qualifications. See “Trustee Experience” below. The Board believes that its leadership structure is consistent with industry practices and is appropriate in light of the size of the Trust and the nature and complexity of its business. In particular:

RISK OVERSIGHT. Risk oversight is a part of the Board’s general oversight of the Portfolio and is addressed as part of various Board and committee activities. Day-to-day risk management functions are subsumed within the responsibilities of the Investment Adviser and other service providers (depending on the nature of the risk), which carry out the Portfolio’s investment management and business affairs. Each of the Investment Adviser and other service providers employ a variety of processes, procedures and controls to identify various events or circumstances that may give rise to risks, to lessen the probability of their occurrence and/or to mitigate the effects of such events or circumstances if they occur. The Investment Adviser and other service providers have their own independent interests in risk management, and their policies and methods of risk management will depend on their functions and business models. The Investment Adviser has a dedicated risk management function that is headed by a Chief Risk Officer.

Currently, the Board receives and reviews risk reports on a quarterly basis from the Investment Adviser’s Chief Risk Officer. The Audit Committee reviews and discusses these reports with the Investment Adviser’s Chief Risk Officer prior to their presentation to the Board. These reports cover risk areas that include, but are not limited to, credit risk, investment risk, operational risk, fiduciary risk, compliance risk, market and liquidity risk and strategic risk. These reports are intended to provide the Trustees with a forward-looking view of risk and the manner in which the Investment Adviser is managing various risks.

The Audit Committee, in addition to its risk management responsibilities, plays an important role in the Board’s risk oversight. Working with the Portfolio’s independent registered accountants, the Audit Committee ensures that the Portfolio’s annual audit scope includes risk-based considerations, such that the auditors consider the risks potentially impacting the audit findings as well as risks to the Portfolio’s financial position and operations.

The Valuation Committee reviews risk related reports regarding the Portfolio on a quarterly basis. These reports are intended to test the valuations of the Portfolio under highly stressed market conditions. The Committee also reviews know your customer reports on a quarterly basis, which are designed to track shareholder concentrations in the Portfolio and the ability of the Portfolio to withstand large redemptions.

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The Ad Hoc Compliance Committee monitors compliance matters affecting the Portfolio. The Ad Hoc Compliance Committee was created on November 13, 2019.

The Board also monitors and reviews the Portfolio’s performance metrics, and regularly confers with the Investment Adviser on performance-related issues.

The Trust’s CCO reports to the Board at least quarterly regarding compliance risk issues. In addition to providing quarterly reports, the CCO provides an annual report to the Board in accordance with the Portfolio’s compliance policies and procedures. The CCO regularly discusses relevant compliance risk issues affecting the Portfolio during meetings with the non-interested Trustees and counsel. The CCO updates the Board on the application of the Portfolio’s compliance policies and procedures and discusses how they mitigate risk. The CCO also reports to the Board immediately regarding any problems associated with the Portfolio’s compliance policies and procedures that could expose (or that might have the potential to expose) the Portfolio to risk.

TRUSTEE EXPERIENCE. Each Trustee is required to possess certain qualities such as integrity, intelligence, the ability to critically discuss and analyze issues presented to the Board and an understanding of a trustee’s fiduciary obligations with respect to a registered investment company. In addition to these qualities, the following is a description of certain other Trustee attributes, skills, experiences and qualifications.

NON-INTERESTED TRUSTEES

Therese M. Bobek: Ms. Bobek retired in 2018 from a 35-year career with PricewaterhouseCoopers, LLP (“PwC”), having served a wide variety of public and privately held clients with external audits, internal auditing and risk advisory services. Ms. Bobek most recently served in PwC’s national office, where she led a nationwide network of partners and managers whose main responsibility was to support audit quality in the field. She now teaches Advanced Auditing in the Masters of Accountancy program at the University of Iowa’s Henry B. Tippie College of Business and also is a director and member of the audit committee of the board of directors of Methode Electronics, Inc., a global developer of custom engineered and application-specific products and solutions. Ms. Bobek has been a Board Member of Metropolitan Family Services and a Board Member of the Illinois Society of CPAs. She has also served as a member and Chair of the University of Iowa Professional Accounting Council, a voluntary council of business leaders supporting accounting education. She has served as a non-interested Trustee of Northern Institutional Funds and Northern Funds since January 2019.

Ingrid LaMae A. de Jongh: Ms. de Jongh served as a partner in the global financial services strategy at Accenture, and was with the global management consulting and professional services firm from 1987 through 2012. While at Accenture, she helped global financial institutions improve their business performance by developing strategies and business models, and implementing business change programs and systems. Since May 2020 she has been the Chief Schooling Officer, and from 2016 to 2020 she was the Head of School Management and Technology at Success Academy Charter Schools, the largest network and highest-performing free, public charter schools in New York City. Ms. de Jongh is a former member of the Board of Carver Bancorp, Inc. in New York City, where she served as a member of the Nominating and Governance Committees and the Compensation Committee. She is currently on the Board of Directors of Bank Leumi USA. Ms. de Jongh had previously served from 2011 to 2013 as a member of the U.S. Department of Commerce’s National Advisory Council for Minority Business Enterprises. She has served as a non-interested Trustee of Northern Institutional Funds and Northern Funds since January 2019.

Mark G. Doll: Mr. Doll has over 40 years of experience in the investment management industry. He was Chief Investment Officer of Northwestern Mutual Life Insurance Company from 2008 to 2012. During that time, he was responsible for over $180 billion in account assets, and managed the Northwestern Mutual Series, Inc., a 1940 Act registered mutual fund complex offering 28 portfolios. During his 40-year career at Northwestern Mutual, Mr. Doll oversaw all aspects of the company’s publicly traded assets. As Chief Investment Officer, he was a member of the seven-person management committee that oversaw all aspects of Northwestern Mutual’s

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asset management and insurance businesses. Mr. Doll’s extensive experience in mutual fund and separate account management provided him with significant knowledge of equity, fixed income and money market funds. He has served as a non-interested Trustee of Northern Institutional Funds and Northern Funds since 2013.

Thomas A. Kloet: Mr. Kloet is a long-time financial industry executive and former Chief Executive Officer of TMX Group, Ltd., a financial services company and operator of stock, derivatives exchanges, their clearing operations and securities depository. As a result of this position, Mr. Kloet is familiar with financial, investment and business matters. He also understands the functions of a board through his service during the past eight years on the Boards of TMX Group, Ltd.; Nasdaq, Inc. (and the Nasdaq Stock Market, LLC as well as certain other subsidiaries of Nasdaq, Inc. where he has served as Board Chair since 2016); Box Options Exchange; FTSE-TMX Global Debt Capital Markets, Inc.; Bermuda Stock Exchange, Inc.; the Investment Industry Regulatory Organization of Canada and the World Federation of Exchanges. He is a certified public accountant, a member of the American Institute of Certified Public Accountants and is an emeritus member of the Board of Elmhurst College. He has served as a non-interested Trustee of Northern Institutional Funds and Northern Funds since 2015.

Mr. Kloet serves on the Board of Directors of Nasdaq, Inc. Northern Trust Corporation (“NTC”), parent company of NTI, and its affiliates (including affiliated fund complexes) pay listing fees, market data fees, GRC (governance risk and compliance) software fees and similar fees to Nasdaq, Inc. and its affiliates, The Nasdaq Stock Market LLC and Nasdaq OMX Nordic OY and BWise Internal Control Inc. (collectively, “Nasdaq”). The total of these payments were $1,889,947 and $2,094,314 in each of 2019 and 2020, respectively, which are immaterial to Nasdaq’s gross revenues. Nasdaq Inc. paid The Northern Trust Company, an affiliate of NTI, $313,077 and $0 in each of 2019 and 2020, respectively, for managing Nasdaq’s pension funds, which are immaterial to NTC’s gross revenues. In consideration of the immaterial amounts involved in the foregoing transactions, Mr. Kloet is not considered to have a material business or professional relationship with NTI or its affiliates.

David R. Martin: As of June 2019, Mr. Martin became Chief Financial Officer for Neo Tech, an electronics manufacturer. Mr. Martin was Vice President, Chief Financial Officer and Treasurer from 2007 to 2016 of Dimensional Fund Advisors LP, a global investment manager that provides its services largely to investment companies or their local equivalent (mutual funds in the United States). The funds are held primarily by clients of independent financial advisors but they are also held by institutional clients (who may invest in separate accounts), pensions and profit sharing plans, corporations, defined contribution plans, endowments, state and municipal entities, and sovereign wealth funds. Mr. Martin had oversight responsibilities for all finance and accounting, real estate and compliance functions while at Dimensional, including the implementation of a global transfer pricing methodology. He also served as a director on eight internal Dimensional boards. During his 35 year career in corporate finance, Mr. Martin also had senior management positions at Janus Capital Group, Inc. and Charles Schwab & Co., Inc. and senior level finance positions at First Interstate Bank of Texas, N.A. and Texas Commerce Bancshares, Inc. Mr. Martin is familiar with the functions of mutual fund boards and their oversight responsibilities and the operations of fund advisers and other service providers. He is also well versed in risk management and financial matters affecting mutual funds. He has served as a non-interested Trustee of Northern Institutional Funds and Northern Funds since 2017.

Cynthia R. Plouché: Ms. Plouché has an extensive background in the financial services industry. Until May 2017, she served as lead Independent Trustee and chair of the Audit Committee of the board of trustees of AXA Premier VIP Trust, a registered investment company. She currently serves as an Independent Trustee of Barings Fund Trust, a registered investment company and an Independent Trustee of Barings Global Short Duration High Yield Fund, a closed-end investment company. She also has served as portfolio manager and chief investment officer for other registered investment advisers. Ms. Plouché is therefore familiar with the functions of mutual fund boards and their oversight responsibilities and the operations of fund advisers and other service providers. In addition, Ms. Plouché served as Township Assessor for Moraine, Illinois, from January 2014 to June 2018. She has served as a non-interested Trustee of Northern Institutional Funds and Northern Funds since 2014.

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Mary Jacobs Skinner: Ms. Skinner was a partner until November 30, 2015 at Sidley Austin LLP, a large international law firm, in which she managed a regulatory-based practice. As a result of this position, Ms. Skinner is familiar with legal, regulatory and financial matters. She was a Harvard Advanced Leadership Fellow in 2016. She also is familiar with the functions of the Board and its oversight responsibilities with respect to the Investment Adviser and other Portfolio service providers as a result of her service as a Trustee of Northern Institutional Funds since 2000 and Northern Funds since 1998.

INTERESTED TRUSTEE

Darek Wojnar, CFA: Mr. Wojnar is the Executive Vice President and Head of the Funds and Managed Accounts Group at NTI. He principally leads the development, management and distribution of Northern Funds, Northern Institutional Funds, FlexShares Trust and related business activities. Mr. Wojnar also oversees the Managed Accounts practice for NTI, which offers investment advisory solutions to financial intermediaries and their clients. With extensive business experience and a history of successfully building strong teams, Mr. Wojnar’s broad executive responsibilities include developing long-term strategies, executing operating plans, managing client and vendor relationships and developing and retaining talented professionals.

Mr. Wojnar has also had a series of executive positions at other fund groups, including head of ETFs for Hartford Funds, managing director and head of US iShares product at BlackRock and executive director at UBS Global Asset Management. He has served as an interested Trustee of Northern Institutional Funds and Northern Funds since January 2019.

STANDING BOARD COMMITTEES. The Board has established four standing committees in connection with its governance of the Trust: Audit, Governance, Valuation and Executive Committees.

The Audit Committee consists of four members: Messrs. Martin (Chairperson), Doll (ex officio), and Kloet (ex officio), and Ms. Bobek. The Audit Committee oversees the audit process and provides assistance to the full Board with respect to fund accounting, tax compliance and financial statement matters. In performing its responsibilities, the Audit Committee selects and recommends annually to the entire Board an independent registered public accounting firm to audit the books and records of the Trust for the ensuing year, and reviews with the firm the scope and results of each audit. The Audit Committee also is designated as the Qualified Legal Compliance Committee under the Sarbanes-Oxley Act of 2002. The Audit Committee convenes at least four times each year to meet with the independent registered public accounting firm to review the scope and results of the audit and to discuss other non-audit matters as requested by the Board’s Chairperson, the Committee Chairperson or the independent registered public accounting firm. During the fiscal year ended November 30, 2021, the Audit Committee convened five times.

The Governance Committee consists of three members: Mses. Plouché (Chairperson), Skinner and Mr. Kloet (ex officio). The functions performed by the Governance Committee include, among other things, selecting and nominating candidates to serve as non-interested Trustees, reviewing and making recommendations regarding Trustee compensation, developing policies regarding Trustee education and, subject to Board oversight, supervising the Trust’s CCO and reviewing information and making recommendations to the Board in connection with the Board’s annual consideration of the Trust’s management, custody and transfer agency and service agreements. During the fiscal year ended November 30, 2021, the Governance Committee convened four times.

As stated above, each Trustee holds office for an indefinite term until the occurrence of certain events. In filling Board vacancies, the Governance Committee will consider nominees recommended by shareholders. Nominee recommendations should be submitted to the Secretary of the Trust, The Northern Trust Company, 50 South LaSalle Street, Chicago, Illinois 60603.

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The Valuation Committee consists of five members: Messrs. Doll (Chairperson), Kloet (ex officio), Martin (ex officio) and Wojnar and Ms. de Jongh. The Valuation Committee is authorized to act for the Board in connection with the valuation of portfolio securities of the Trust’s portfolios in accordance with the Trust’s valuation procedures. During the fiscal year ended November 30, 2021, the Valuation Committee convened four times.

The Executive Committee consists of four members: Messrs. Doll, Kloet (Chairperson) and Martin, and Ms. Plouché. The Executive Committee is comprised of the Chairperson of the Board as well as the Chairpersons of the Governance, Valuation and Audit Committees, with the remaining Trustees each serving as an alternate in the event of an emergency. The Executive Committee is granted the power to act on behalf of the full Board in the management of the business and affairs of the Trust, to be exercised when circumstances impair the ability of the Board or its committees to conduct business. In particular, the Executive Committee may take action with respect to: (1) the valuation of securities; and (2) the suspension of redemptions. The Executive Committee was formed on May 21, 2015 and will convene as necessary upon notice by the Chairperson of the Committee. During the fiscal year ended November 30, 2021, the Executive Committee did not meet.

TRUSTEE OWNERSHIP OF PORTFOLIO SHARES. Shares of the Portfolio are offered to institutional investors acting on their own behalf or on behalf of their customers and other beneficial owners (“Customers”). For this reason, the Trustees may not make direct investments in the Portfolio. The following table shows the dollar range of shares owned by each Trustee in the Portfolio and other investment portfolios of the Northern Institutional Funds and Northern Funds.

TRUSTEE AND OFFICER COMPENSATION. The Trust pays each Trustee who is not an officer, director or employee of Northern Trust Corporation or its subsidiaries annual fees for his or her services as a Trustee of the Trust and as a member of the respective Board committees. In recognition of their services, the fees paid to the Board and Committee chairpersons are larger than the fees paid to other members of the Board and Committees. The Trustees also are reimbursed for travel expenses incurred in connection with attending such meetings. The Trust also may pay the incidental costs of a Trustee to attend training or other types of conferences relating to the investment company industry.

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The following tables set forth certain information with respect to the compensation of each non-interested and interested Trustee of the Trust for the fiscal year ended November 30, 2020:

Non-Interested Trustees

Interested Trustees

The Trust does not provide pension or retirement benefits to its Trustees.

Prior to August 22, 2013, each Trustee was entitled to participate in the Northern Institutional Funds Deferred Compensation Plan (the “D.C. Plan”). Effective August 22, 2013, the Trustees may no longer defer their compensation. Any amounts deferred and invested under the D.C. Plan shall remain invested pursuant to the terms of the D.C. Plan. Under the D.C. Plan, a Trustee may have elected to have his or her deferred fees treated as if they had been invested by the Trust in the shares of the Global Tactical Asset Allocation Fund of Northern Funds or the U.S. Government Portfolio of the Trust and/or at the discretion of the Trust, another money market fund selected by the Trust that complied with the provisions of Rule 2a-7 under the 1940 Act or one or more short-term fixed-income instruments selected by the Trust that are “eligible securities” as defined by that rule. The amount paid to the Trustees under the D.C. Plan will be determined based upon the performance of such investments. Deferral of Trustees’ fees will not obligate the Trust to retain the service of any Trustee or obligate the Portfolio to any level of compensation to the Trustee. The Trust may invest in underlying securities without shareholder approval.

The Trust’s officers do not receive fees from the Trust for services in such capacities. Northern Trust Corporation and/or its affiliates, of which Ms. Chappell and Messrs. Carberry, Crabill, Del Real, Ewing, Gennovario, Martins, Meehan, O’Rourke, Pryszcz, and Rein are officers, receive fees from the Trust as Investment Adviser, Custodian and Transfer Agent.

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CODE OF ETHICS

The Trust and its Investment Adviser have adopted codes of ethics (the “Codes of Ethics”) under Rule 17j-1 of the 1940 Act. Northern Funds Distributors, LLC (“NFD” or the “Distributor”), an unaffiliated principal underwriter of the Trust, is exempt from the requirements of Rule 17j-1(c)(1) and (c)(2) of the 1940 Act. The Codes of Ethics permit personnel, subject to the Codes of Ethics and their provisions, to invest in securities, including securities that may be purchased or held by the Trust.

INVESTMENT ADVISER, TRANSFER AGENT AND CUSTODIAN

NTI, an indirect subsidiary of Northern Trust Corporation, serves as the Investment Adviser and provides investment advisory and administration services to the Portfolio. Northern Trust Corporation is regulated by the Board of Governors of the Federal Reserve System as a financial holding company under the U.S. Bank Holding Company Act of 1956, as amended. NTI is located at 50 South LaSalle Street, Chicago, Illinois 60603.

NTI is an Illinois State Banking Corporation and an investment adviser registered under the Investment Advisers Act of 1940, as amended. It primarily manages assets for institutional and individual separately managed accounts, investment companies and bank common and collective funds.

TNTC is the principal subsidiary of Northern Trust Corporation and serves as the sub-administrator, transfer agent and custodian for the Portfolio. TNTC is located at 50 South LaSalle Street, Chicago, Illinois 60603. TNTC is a member of the Federal Reserve System. Since 1889, TNTC has administered and managed assets for individuals, institutions and corporations. Unless otherwise indicated, NTI and TNTC are referred to collectively in this SAI as “Northern Trust.”

As of September 30, 2021, Northern Trust Corporation, through its affiliates, had assets under custody of $12.25 trillion, and assets under investment management of $1.53 trillion.

Management Agreement

NTI provides the Portfolio with investment advisory and administration services under a management agreement (“Management Agreement,”) The Management Agreement has a single fee structure covering advisory and administration services. Under the Management Agreement with NTI for the Portfolio, subject to the general supervision of the Board, NTI makes decisions with respect to, and places orders for, all purchases and sales of portfolio securities for the Portfolio and also provides certain administration services to the Portfolio.

NTI is also responsible for monitoring and preserving the records required to be maintained under the regulations of the SEC (with certain exceptions unrelated to its activities for the Trust). In making investment recommendations for the Portfolio, if any, investment advisory personnel of NTI may not inquire or take into consideration whether issuers of securities proposed for purchase or sale for the Portfolio’s accounts are customers of TNTC’s commercial banking department. These requirements are designed to prevent investment advisory personnel for the Portfolio from knowing which companies have commercial business with TNTC and from purchasing securities where they know the proceeds will be used to repay loans to the bank.

The Management Agreement has been approved by the Board, including the “non-interested” Trustees and by shareholders of the Portfolio.

In connection with portfolio transactions for the Portfolio, which are generally done at a net price without a broker’s commission, the Management Agreement with the Trust provides that the Investment Adviser shall attempt to obtain the best net price and execution. Purchases by the Portfolio from underwriters of portfolio securities normally include a commission or concession paid by the issuer to the underwriter, and purchases from dealers include the spread between the dealer’s cost for a given security and the resale price of the security.

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On occasions when the Investment Adviser deems the purchase or sale of a security to be in the best interests of the Portfolio as well as other fiduciary or agency accounts (“other accounts”) managed by the Investment Adviser, the Management Agreement provides that the Investment Adviser, to the extent permitted by applicable laws and regulations, may aggregate the securities to be sold or purchased for the Portfolio with those to be sold or purchased for such other accounts in order to obtain the best net price and execution. In such an event, allocation of the securities so purchased or sold, as well as the expenses incurred in the transaction, will be made by the Investment Adviser in the manner it considers to be the most equitable and consistent with its obligations to the Portfolio and other accounts involved. In some instances, this procedure may adversely affect the size of the position obtainable for the Portfolio or the amount of the securities that are able to be sold for the Portfolio. To the extent that the execution and price available from more than one broker or dealer are believed to be comparable, the Management Agreement permits the Investment Adviser, at its discretion but subject to applicable law, to select the executing broker or dealer on the basis of the Investment Adviser’s opinion of the reliability and quality of the broker or dealer.

The Investment Adviser is also responsible for providing certain administration services to the Portfolio pursuant to the Management Agreement. Subject to the general supervision of the Board, the Investment Adviser provides supervision of all aspects of the Portfolio’s operations and performs the customary services of an administrator, including but not limited to the following corporate treasury, secretarial and “blue sky” services: (a) maintaining office facilities and furnishing corporate officers for the Portfolio; (b) furnishing data processing services, clerical services, and executive and administrative services and standard stationery and office supplies; (c) performing all functions ordinarily performed by the office of a corporate treasurer, and furnishing the services and facilities ordinarily incident thereto, such as expense accrual monitoring and payment of the Portfolio’s bills, preparing monthly reconciliation of the Portfolio’s expense records, updating projections of annual expenses, preparing materials for review by the Board, and compliance testing; (d) preparing and arranging for printing of financial statements; (e) preparing and filing the Portfolio’s federal and state tax returns (other than those required to be filed by the Portfolio’s custodian and transfer agent) and providing shareholder tax information to the Portfolio’s transfer agent; (f) assisting the Portfolio’s Investment Adviser, at the Investment Adviser’s request, in monitoring and developing compliance procedures for the Portfolio which include, among other matters, procedures to assist the Investment Adviser in monitoring compliance with the Portfolio’s investment objective, policies, restrictions, tax matters and applicable laws and regulations; (g) assisting in product development; (h) performing oversight/management responsibilities such as the supervision and coordination of certain of the Portfolio’s service providers; (i) performing corporate secretarial services such as assisting in maintaining corporate records and the good standing status of the Trust in its state of organization; (j) performing “blue sky” compliance functions; (k) monitoring the Portfolio’s arrangements with respect to services provided by service organizations to their customers who are the beneficial owners of shares, pursuant to agreements between the Portfolio and such service organizations; (l) performing certain legal services such as preparing and filing annual Post-Effective Amendments to the Portfolio’s registration statement and other SEC filings for the Portfolio; and (m) computing and determining on the days and at the times specified in the Portfolio’s then-current Prospectus, the NAV of each share of the Portfolio and the net income of the Portfolio. Pursuant to a Sub-Administration Agreement, NTI has delegated certain of the above administration services to TNTC.

Unless sooner terminated, the Trust’s Management Agreement will continue in effect until June 30, 2022. Thereafter, the Management Agreements will continue in effect for successive 12-month periods, provided that the continuance is approved at least annually (i) by the vote of a majority of the Trustees who are not parties to the Management Agreement or “interested persons” (as such term is defined in the 1940 Act) of any party thereto, cast at a meeting called for the purpose of voting on such approval and (ii) by the Trustees or by the vote of a majority of the outstanding shares of such Portfolio (as defined under “Description of Shares”).

The Management Agreement is terminable at any time without penalty by the Trust (by specified Trustee or shareholder action) or by the Investment Adviser, on 60 days’ written notice.

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The Management Agreement provides that the Investment Adviser may render similar services to others so long as its services under the Management Agreement are not impaired thereby. The Management Agreement also provides that the Trust will indemnify the Investment Adviser against certain liabilities (including, with respect to the advisory services provided by the Investment Adviser under the Management Agreement, liabilities under the federal securities laws relating to untrue statements or omissions of material fact and actions that are in accordance with the terms of the Management Agreement) or, in lieu thereof, contribute to resulting losses.

Northern Trust Corporation and its affiliates may act as an underwriter of various securities. Under the 1940 Act, the Portfolio is precluded, subject to certain exceptions, from purchasing in the primary market those securities with respect to which Northern Trust Corporation or an affiliate is serving as a principal underwriter. In the opinion of Northern Trust Corporation, this limitation will not significantly affect the ability of the Portfolio to pursue their investment objective.

In the Management Agreement, the Investment Adviser agrees that the name “Northern” may be used in connection with the Trust’s business on a royalty-free basis. TNTC has reserved to itself the right to grant the non-exclusive right to use the name “Northern” to any other person. The Management Agreement provides that at such time as the Management Agreement is no longer in effect, the Trust will cease using the name “Northern.”

As compensation for advisory services and administration services and the assumption of related expenses, NTI is entitled to a management fee, computed daily and payable monthly, at the annual rates set forth in the table below (expressed as a percentage of the Portfolio’s average daily net assets):

For the fiscal years indicated below, the amount of management fees (after management fee waivers or reimbursements, if any) incurred by the Portfolio was as follows:

Transfer Agency and Service Agreement

Under its Transfer Agency and Service Agreement with the Trust, TNTC as Transfer Agent has undertaken to perform certain services for the Portfolio described in this SAI, including but not limited to the following: (i) answer shareholder inquiries and respond to requests for information regarding the Trust; (ii) process purchase and redemption transactions; (iii) establish and maintain shareholder accounts and subaccounts; (iv) furnish confirmations in accordance with applicable law, and provide periodic account statements to each shareholder; (v) furnish proxy statements and proxies, annual and semi-annual financial statements, and dividend, distribution and tax notices to shareholders; (vi) act as dividend disbursing agent; (vii) report abandoned property to state authorities; (viii) impose, collect, account for and administer redemption fees if applicable on redemptions and exchanges; (ix) process, handle and account for all “as of ” transactions; (x) conduct daily reviews of management reports related to late trading and daily value reviews with respect to the Trust’s excessive trading policies; and (xi) maintain appropriate records relating to its services. The Trust may appoint one or more sub-transfer agents in the performance of its services.

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As compensation for the services rendered by TNTC under the Transfer Agency and Service Agreement and the assumption by TNTC of related expenses with respect to the Portfolio described in this SAI, TNTC is entitled to a fee from the Trust payable monthly, at an annual rate of 0.015% of the average daily net assets of the Portfolio In addition, TNTC may be reimbursed for certain expenses as provided under the Transfer Agency and Service Agreement. Northern Trust may enter into agreements with financial intermediaries through which customers own shares of the Siebert Williams Shank shares class of the Portfolio, pursuant to which Northern Trust pays these financial intermediaries for providing certain shareholder services described in the preceding paragraph. The payments made by Northern Trust to financial intermediaries will be paid by Northern Trust and will not represent an additional expense to the Portfolio or its shareholders. Conflict of interest restrictions under state and federal law (including the Employee Retirement Income Security Act of 1974 (“ERISA”)) may apply to the receipt by such financial intermediaries of such compensation in connection with the investment of fiduciary funds in Siebert Williams Shank shares of the Portfolio. The Transfer Agency and Service Agreement shall continue indefinitely until terminated by the Trust by not less than 90 days’ written notice or by the Transfer Agent by not less than six months written notice.

For the fiscal years indicated below, the amount of transfer agent fees paid by the Portfolio was as follows:

Custody Agreement

Under its Custody Agreement with the Trust, TNTC (the “Custodian”), on behalf of the Portfolio (i) holds the Portfolio’s cash and securities, (ii) maintains such cash and securities in separate accounts in the name of the Portfolio, (iii) makes receipts and disbursements of funds on behalf of the Portfolio, (iv) receives, delivers and releases securities on behalf of the Portfolio, (v) collects and receives all income, principal and other payments in respect of the Portfolio’s investments held by the Custodian, (vi) to the extent applicable to the Portfolio, is responsible for the Portfolio’s foreign custody arrangements pertaining to its activities under the Custody Agreement, and (vii) maintains all records of its activities and obligations under the Custody Agreement. The Custodian may appoint one or more sub-custodians and shall oversee the maintenance by any sub-custodian of any securities or other assets held by the Portfolio. The Custody Agreement provides that the Custodian will use reasonable care, prudence and diligence with respect to its obligations under the Custody Agreement and the safekeeping of the Portfolio’s property and shall be liable to and shall indemnify the Trust from and against any loss that occurs as a result of the failure of the Custodian or a sub-custodian to exercise reasonable care, prudence and diligence with respect to their respective obligations under the Custody Agreement and the safekeeping of such property. The Custodian is not responsible for any act, omission, or default of, or for the solvency of, any eligible securities depository, nor is the Custodian responsible for any act, omission, or default of, or for the solvency of, any broker or agent that it or a sub-custodian appoints and uses unless such appointment and use is made or done negligently or in bad faith.

Effective August 1, 2019, the Custodian receives from the Trust, with respect to services rendered to the Portfolio: (i) an annual fixed fee; plus (ii) an annual percentage of the Portfolio’s average daily net assets; plus (iii) an annual fixed dollar fee for each portfolio holding; plus (iv) fixed dollar fees for each trade in portfolio securities; plus (v) reimbursement for other out-of-pocket fees incurred by the Custodian.

Prior to August 1, 2019 as compensation for the domestic custody services rendered with respect to the Portfolio, and the assumption by the Custodian of certain related expenses, the Custodian was entitled to payment from the Trust as follows: (a) a basic custodial fee of (i) $18,000 annually for the Portfolio; plus (ii) 1/100th of 1% annually of the Portfolio’s average daily net assets to the extent they exceed $100 million, plus (b) a fixed dollar fee for each trade in portfolio securities; plus (c) a fixed dollar fee for each time that the Custodian

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receives or transmits funds via wire; plus (d) reimbursement of other out-of-pocket expenses incurred by the Custodian. The fees referred to in clauses (b) and (c) are subject to annual upward adjustments based on increases in the CPI-U, provided that the Custodian may permanently or temporarily waive all or any portion of any upward adjustment.

The Custodian’s fees under the Custody Agreement are subject to reduction based on the Portfolio’s daily-uninvested U.S. cash balances (if any). The Custody Agreement shall continue indefinitely until terminated by the Trust by not less than 60 days’ written notice, or by the Custodian by not less than 90 days’ written notice.

For the fiscal years indicated below, the amount of custodian fees (after custodian credits, if any) paid by the Portfolio was as follows:

BROKERAGE TRANSACTIONS

For the fiscal years ended November 30, 2020, 2019 and 2018, all portfolio transactions for the Portfolio were executed on a principal basis and, therefore, no brokerage commissions were paid by the Portfolio. Purchases by the Portfolio from underwriters of portfolio securities, however, normally include a commission or concession paid by the issuer to the underwriter, and purchases from dealers include the spread between the dealer’s cost for a given security and the resale price of the security. No commissions were paid by the Portfolio to any direct or indirect “affiliated” persons (as defined in the 1940 Act) of the Portfolio.

The Trust is required to identify any securities of its “regular brokers or dealers” as defined in Rule 10b-1 under the 1940 Act or of their parents that the Portfolio acquired during its most recent fiscal year.

“Regular brokers or dealers” under Rule 10b-1 include (a) the ten brokers or dealers that received the greatest amount of brokerage commissions by virtue of direct or indirect participations in the company’s portfolio transactions; (b) the ten brokers or dealers that engaged as principal in the largest dollar amount of portfolio transactions of the investment company; and (c) the ten brokers or dealers that sold the largest amount of securities of the investment company. The regular brokers or dealers whose securities (or whose parent companies’ securities) the Portfolio acquired during the fiscal year ended November 30, 2020 and the amount of securities of such regular brokers or dealers held by the Portfolio at November 30, 2020 are as follows:

Treasury Portfolio

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CONFLICTS OF INTEREST

NTI’s portfolio managers are often responsible for managing one or more portfolios, as well as other client accounts, including ETFs, separate accounts and other pooled investment vehicles. A portfolio manager may manage various client accounts that may have materially higher or lower fee arrangements than the Portfolio. The side-by-side management of these accounts may raise potential conflicts of interest relating to cross trading, the allocation of investment opportunities and the aggregation and allocation of trades. In addition, while portfolio managers generally only manage accounts with similar investment strategies, it is possible that due to varying investment restrictions among accounts, certain investments are made for some accounts and not others or conflicting investment positions could be taken among accounts. Some portfolio managers may be dual officers of one or more NTI affiliates and undertake investment advisory duties for the affiliates. The portfolio managers have a responsibility to manage all client accounts in a fair and equitable manner. NTI takes reasonable steps to obtain the best qualitative execution of securities transactions. NTI has a duty to treat its clients fairly and no account may be given preferential treatment in connection with an investment opportunity and when aggregating and allocating securities transactions. To this end, NTI has developed policies and procedures designed to mitigate and manage the potential conflicts of interest that may arise from side-by-side management.

NTI may have a financial incentive to favor accounts with performance-based fees because there may be an opportunity to earn greater fees on such accounts compared to accounts without performance-based fees. As a result, NTI may have an incentive to direct its best investment ideas to or allocate the sequencing of trades in favor of the account that pays a performance fee. NTI may also have an incentive to recommend investments that may be riskier or more speculative than those that it would recommend under a different fee arrangement.

NTI may invest client accounts in affiliated investment pools. If appropriate and consistent with the client’s investment objectives and applicable law, NTI may recommend to clients investment pools in which it or an affiliate provides services for a fee. NTI has an incentive to allocate investments to these types of affiliated investment pools in order to generate additional fees for NTI or its affiliates. In addition, NTI could direct its best investment ideas to these investment products or investment pools to the potential disadvantage of the Portfolio.

As NTI becomes aware of additional potential or actual conflicts of interest, they will be reviewed on a case-by-case basis.

NTI manages its client accounts consistent with applicable law and follows its own policies and procedures that are reasonably designed to treat clients fairly and to prevent any client or group of clients from being systematically favored or disadvantaged.

NTI provides advice and makes investment decisions for client accounts that it believes are consistent with each client’s stated investment objectives and guidelines. Advice given to clients or investment decisions made for clients may differ from, or may conflict with, advice given or investment decisions made for clients of an NTI affiliate. Conflicts may also arise because portfolio decisions regarding the Trust may benefit NTI or its affiliates or another account or portfolio managed by NTI or its affiliates. Actions taken with respect to NTI’s and its affiliates’ other portfolios or accounts managed by them may adversely impact the Portfolio, and actions taken by the Portfolio may benefit NTI or its affiliates or their other portfolios or accounts. NTI may also invest in the same securities that it or its affiliates recommend to clients.

When NTI or an affiliate currently holds for its own benefit the same securities as a client, it could be viewed as having a potential conflict of interest.

Generally, NTI will not, as principal for its own account, buy securities from or sell securities to any client. It is possible that an affiliate, will, as principal, purchase securities from or sell securities to its clients.

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From time to time securities to be sold on behalf of a client may be suitable for purchase by another client. In such instances, if NTI determines in good faith that the transaction is in the best interest of each client, it may arrange for the securities to be crossed between client accounts at an independently determined fair market value and in compliance with the 1940 Act, if applicable. Cross-trades present conflicts of interest, as there may be an incentive for NTI to favor one client to the disadvantage of another. Cross-trades are only effected as permitted under applicable law and regulation and consistent with the client’s guidelines, with any restrictions. NTI does not receive fees or commissions for these transactions. NTI and the Trust have adopted policies on cross-trades that may be effected between the Portfolio and another client account. NTI conducts periodic reviews of trades for consistency with these policies. NTI has established certain policies and procedures designed to address conflicts of interest that may arise between its employees and clients as well as between clients and NTI or its affiliates.

NTI’s employees must act in the best interests of its clients and generally do not have knowledge of proprietary trading positions or certain other operations of affiliates.

Receipt of research from brokers who execute client transactions involve conflicts of interest. To the extent that NTI uses commissions to obtain research services for NTI or TNTC, NTI or TNTC will receive a benefit as it will not have to pay for the research, products or services itself. NTI may, therefore, have an incentive to select or recommend a broker-dealer based on its interest in receiving research rather than in obtaining the lowest commission rate on the transaction. NTI or TNTC may also obtain research services from brokerage commissions incurred by client accounts that may not directly benefit such client accounts. Similarly, clients may benefit from research even if trades placed on their behalf did not contribute to the compensation of the broker-dealer providing such research. NTI and TNTC do not seek to allocate research services to client accounts proportionately to the commissions that the client accounts generate.

Also, NTI and TNTC may receive products and services that are mixed use. In these cases, NTI or TNTC will use commissions to pay only for the eligible portion of the product or service that assists NTI or TNTC in the investment decision-making process. Any ineligible portion of the product will be paid directly by NTI or TNTC. NTI or TNTC makes a good faith effort to reasonably allocate such items and keeps records of such allocations although clients should be aware of the potential conflicts of interest.

NTI may provide investment advice to its affiliates and may provide investment advisory services to affiliates’ clients or act as an investment adviser to the registered or unregistered investment pools in which these clients may invest. TNTC and NTI share a common trading desk and may have shared arrangements with investment research vendors. Also, these affiliates may provide marketing services to NTI, including the referral of certain clients.

NTI may have common management and officers with some of its affiliates. NTI shares facilities with affiliates and relies on TNTC and other affiliates for various administrative support, including information technology, human resources, business continuity, legal, compliance, finance, enterprise risk management, internal audit and general administrative support.

NTI’s affiliations may create potential conflicts of interest. NTI seeks to mitigate the potential conflicts of interest to ensure accounts are managed at all times in a client’s best interests and in accordance with client investment objectives and guidelines through regular account reviews attended by investment advisory, compliance and senior management staff. NTI also seeks to mitigate potential conflicts of interest through a governance structure and by maintaining policies and procedures that include, but are not limited to, personal trading, custody and trading.

Various non-affiliated investment advisers that may manage NTI client accounts, or may be recommended to NTI clients, may use an NTI affiliate for banking, trust, custody, administration, brokerage and related services for which NTI’s affiliate may receive fees. NTI does not recommend or utilize non-affiliated investment advisers based upon their use of NTI affiliates.

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Given the interrelationships among NTI and its affiliates, there may be other or different potential conflicts of interest that arise in the future that are not included in this section.

To the extent permitted by applicable law, NTI may make payments to authorized dealers and other financial intermediaries (“Intermediaries”) from time to time to promote the Portfolio. These payments may be made out of NTI’s assets, or amounts payable to NTI rather than as a separately identifiable charge to the Portfolio. These payments may compensate Intermediaries for, among other things: marketing the Portfolio; access to the Intermediaries’ registered representatives or salespersons, including at conferences and other meetings; assistance in training and education of personnel; marketing support; and/or other specified services intended to assist in the distribution and marketing of the Portfolio. The payments may also, to the extent permitted by applicable regulations, contribute to various non-cash and cash incentive arrangements to promote certain products, as well as sponsor various educational programs, sales contests and/or for subaccounting, administrative and/or shareholder processing services that are in addition to the fees paid for these services for such products.

PROXY VOTING

The Trust has delegated the voting of portfolio securities to the Investment Adviser. The Investment Adviser has adopted the proxy voting policies and procedures applicable to Northern Trust Corporation and its affiliates (the “Northern Proxy Voting Policy”) for the voting of proxies on behalf of client accounts for which the Investment Adviser has voting discretion, including the Portfolio. Under the Northern Proxy Voting Policy, shares are to be voted in the best interests of the Portfolio.

A Proxy Committee comprised of senior investment and compliance officers of Northern Trust Corporation, including officers of the Investment Adviser, has adopted certain guidelines (the “Proxy Guidelines”) concerning various corporate governance issues. The Proxy Committee has the responsibility for the content, interpretation and application of the Proxy Guidelines and may apply these Proxy Guidelines with a measure of flexibility. The Investment Adviser has retained an independent third party proxy voting service (the “Service Firm”) to review proxy proposals and to make voting recommendations to the Proxy Committee in a manner consistent with the Proxy Guidelines. The Proxy Committee will apply the Proxy Guidelines as discussed below to any such recommendation.

The Proxy Guidelines provide that the Proxy Committee will generally vote for or against various proxy proposals, usually based upon certain specified criteria. As an example, the Proxy Guidelines provide that the Proxy Committee will generally vote in favor of:

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The Proxy Guidelines also provide that the Proxy Committee will generally vote against:

For proxy proposals that under the Proxy Guidelines are to be voted on a case by case basis, the Proxy Committee provides supplementary instructions to the Service Firm to guide it in making vote recommendations.

Except as otherwise provided in the Northern Proxy Voting Policy, the Proxy Committee may vote proxies contrary to the recommendations of the Service Firm if it determines that such action is in the best interest of the Portfolio. In exercising its discretion, the Proxy Committee may take into account a wide array of factors relating to the matter under consideration, the nature of the proposal and the company involved. As a result, the Proxy Committee may vote in one manner in the case of one company and in a different manner in the case of another where, for example, the past history of the company, the character and integrity of its management, the role of

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outside directors, and the company’s record of producing performance for investors justifies a high degree of confidence in the company and the effect of the proposal on the value of the investment. Similarly, poor past performance, uncertainties about management and future directions, and other factors may lead the Proxy Committee to conclude that particular proposals present unacceptable investment risks and should not be supported. In addition, the Proxy Committee also evaluates proposals in context. For example, a particular proposal may be acceptable standing alone, but objectionable when part of an existing or proposed package. Special circumstances may also justify casting different votes for different clients with respect to the same proxy vote.

The Investment Adviser or its affiliates may occasionally be subject to conflicts of interest in the voting of proxies due to business or personal relationships it maintains with persons having an interest in the outcome of certain votes. For example, the Investment Adviser or its affiliates may provide trust, custody, investment management, brokerage, underwriting, banking and related services to accounts owned or controlled by companies whose management is soliciting proxies. Occasionally, the Investment Adviser or its affiliates may also have business or personal relationships with other proponents of proxy proposals, participants in proxy contests, corporate directors or candidates for directorships. The Investment Adviser may also be required to vote proxies for securities issued by Northern Trust Corporation or its affiliates or on matters in which the Investment Adviser or its affiliates have a direct financial interest, such as shareholder approval of a change in the advisory fees paid by the Portfolio. The Investment Adviser seeks to address such conflicts of interest through various measures, including the establishment, composition and authority of the Proxy Committee and the retention of the Service Firm to perform proxy review and vote recommendation functions. The Proxy Committee has the responsibility to determine whether a proxy vote involves a conflict of interest and how the conflict should be addressed in conformance with the Northern Proxy Voting Policy. The Proxy Committee may resolve such conflicts in any of a variety of ways, including without limitation the following: (i) voting in accordance with the Proxy Guidelines based recommendation of the Service Firm; (ii) voting in accordance with the recommendation of an independent fiduciary appointed for that purpose; (iii) voting pursuant to client direction by seeking instructions from the Board; or (iv) by voting pursuant to a “mirror voting” arrangement under which shares are voted in the same manner and proportion as shares over which the Investment Adviser does not have voting discretion. The method selected by the Proxy Committee may vary depending upon the facts and circumstances of each situation.

The Investment Adviser may choose not to vote proxies in certain situations. This may occur, for example, in situations where the exercise of voting rights could restrict the ability to freely trade the security in question (as is the case, for example, in certain foreign jurisdictions known as “blocking markets”). In circumstances in which the Service Firm does not provide recommendations for a particular proxy, the Proxy Committee may obtain recommendations from analysts at the Investment Adviser who review the issuer in question or the industry in general. The Proxy Committee will apply the Proxy Guidelines as discussed above to any such recommendation.

This summary and the Northern Proxy Voting Policy and Proxy Guidelines, as adopted by the Investment Adviser, are posted in the Account Resources section of the Trust’s website, northerntrust.com/institutional. You may also obtain, upon request and without charge, a paper copy of the Northern Proxy Voting Policy and Proxy Guidelines or an SAI by calling 800-637-1380.

Information regarding how the Portfolio voted proxies, if any, relating to portfolio securities for the most recent 12 month period ended June 30 will be available, without charge, upon request, by contacting the Investment Adviser at 800-637-1380 or Northern Trust or by visiting the Northern Institutional Funds’ website at northerntrust.com/institutional or the SEC’s website, sec.gov.

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DISTRIBUTOR

The Trust, on behalf of the Portfolio, has entered into a distribution agreement (the “Distribution Agreement”) under which NFD, with principal offices at Three Canal Plaza, Suite 100, Portland, Maine 04101, as agent, distributes the shares of the Portfolio on a continuous basis. NFD continually distributes shares of the Portfolio on a best efforts basis. NFD has no obligation to sell any specific quantity of Portfolio shares. NFD and its officers have no role in determining the investment policies or which securities are to be purchased or sold by the Trust.

The Investment Adviser pays the cost of printing and distributing prospectuses to persons who are not shareholders of the Trust (excluding preparation and typesetting expenses) and of certain other distribution efforts. No compensation is payable by the Trust to NFD for such distribution services. However, the Investment Adviser has entered into an agreement (the “Distribution Services Agreement”) with NFD under which it makes payments to NFD in consideration for certain distribution-related services. The payments made by the Investment Adviser to NFD under the Distribution Services Agreement do not represent an additional expense to the Trust or its shareholders. The Distribution Agreement provides that the Trust will indemnify NFD against certain liabilities relating to untrue statements or omissions of material fact except those resulting from the reliance on information furnished to the Trust by NFD, or those resulting from the willful misfeasance, bad faith or negligence of NFD, or NFD’s breach of confidentiality.

Under a License Agreement (the “License Agreement”) with Foreside Distributors, LLC (“Foreside Distributors”), Northern Trust Corporation agrees that the name “Northern Funds” may be used by Foreside Distributors and its subsidiary, NFD, in connection with providing services to the Trust on a royalty-free basis. Northern Trust Corporation has reserved to itself the right to grant the non-exclusive right to use the name “Northern Funds” to any other person. The License Agreement provides that at such time as the License Agreement is no longer in effect, Foreside Distributors and NFD will cease using the name “Northern Funds.”

COUNSEL AND INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

Stradley Ronon Stevens & Young, LLP, located at 2005 Market Street, Suite 2600, Philadelphia, Pennsylvania 19103, serves as counsel to the Trust, as well as its non-interested Trustees.

Deloitte & Touche LLP, an independent registered public accounting firm, 111 South Wacker Drive, Chicago, Illinois 60606, has been appointed to serve as an independent registered public accounting firm for the Trust. In addition to audit services, an affiliate of Deloitte & Touche LLP reviews the Trust’s federal and state tax returns.

IN-KIND PURCHASES AND REDEMPTIONS

Payment for shares of the Portfolio may, in the discretion of Northern Trust, be made in the form of securities that are permissible investments for the Portfolio as described in the Prospectus. For further information about this form of payment, contact the Transfer Agent. In connection with an in-kind securities payment, the Portfolio will require, among other things, that the securities be valued on the day of purchase in accordance with the pricing methods used by the Portfolio and that the Portfolio receive satisfactory assurances that it will have good and marketable title to the securities received by it; that the securities be in proper form for transfer to the Portfolio; and that adequate information be provided concerning the basis and other tax matters relating to the securities.

Although the Portfolio generally will redeem shares in cash, the Portfolio reserves the right to pay redemptions by a distribution in-kind of securities (instead of cash) from the Portfolio. The securities distributed in-kind would be readily marketable and would be valued for this purpose using the same method employed in calculating the Portfolio’s NAV per share. If a shareholder receives redemption proceeds in-kind, the shareholder should expect to incur transaction costs upon the disposition of the securities received in the redemption.

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REDEMPTION FEES AND REQUIREMENTS

Shares of the Portfolio are sold and generally redeemed without any purchase or redemption charge imposed by the Trust.

The exercise of voting rights and the delivery to Customers of shareholder communications from the Trust will be governed by the Customers’ account agreements with the Institutions. Customers should read the Prospectus in connection with any relevant agreement describing the services provided by an Institution and any related requirements and charges, or contact the Institution at which the Customer maintains its account for further information.

EXPENSES

Except as set forth above and in this SAI, the Portfolio is responsible for the payment of its expenses. These expenses include, without limitation: the fees and expenses payable to the Investment Adviser, Transfer Agent and Custodian; brokerage fees and commissions; fees for the registration or qualification of Portfolio shares under federal or state securities laws; taxes; interest; costs of liability insurance, fidelity bonds, indemnification or contribution, any costs, expenses or losses arising out of any liability of, or claim for damages or other relief asserted against the Trust for violation of any law; legal, tax and auditing fees and expenses; expenses of preparing and printing prospectuses, statements of additional information, proxy materials, reports and notices and distributing of the same to the Portfolio’s shareholders and regulatory authorities; compensation and expenses of its non-interested Trustees; payments to service organizations; fees of industry organizations such as the Investment Company Institute and Mutual Fund Directors Forum; acquired fund fees and expenses; expenses of third party consultants engaged by the Board; expenses in connection with the negotiation and renewal of the revolving credit facility; and miscellaneous and extraordinary expenses incurred by the Trust.

NTI has contractually agreed to reimburse a portion of the operating expenses of the Portfolio (other than certain excepted expenses, i.e., service fees, acquired fund fees and expenses, the compensation paid to each Independent Trustee of the Trust, expenses of third-party consultants engaged by the Board, membership dues paid to the Investment Company Institute and Mutual Fund Directors Forum, expenses in connection with the negotiation and renewal of the revolving credit facility, extraordinary expenses and interest) so that “Total Annual Portfolio Operating Expenses After Expense Reimbursement” do not exceed the amount shown in the footnote to the table under the caption “Fees and Expenses of the Portfolio” in the Portfolio’s Portfolio Summary during the current fiscal year. The “Total Annual Portfolio Operating Expenses After Expense Reimbursement” for the Portfolio may be higher than the contractual limitation for the Portfolio as a result of certain excepted expenses that are not reimbursed. The contractual expense reimbursement arrangement with respect to the Portfolio is expected to continue until at least December 31, 2022. The expense reimbursement arrangement will continue automatically for periods of one year (each such one-year period, a “Renewal Year”). The arrangement with respect to the Portfolio may be terminated, as to any succeeding Renewal Year, by NTI or the Portfolio upon 60 days’ written notice prior to the end of the current Renewal Year. The Board may terminate the arrangement at any time with respect to the Portfolio if it determines that it is in the best interests of the Portfolio and its shareholders.

For the fiscal years indicated below, NTI contractually reimbursed expenses for the Portfolio as follows:

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NTI may reimburse additional expenses or waive all or a portion of the management fees of the Portfolio from time to time, including to avoid a negative yield. Any such additional expense reimbursement or waiver would be voluntary and could be implemented, increased or decreased, or discontinued at any time. There is no guarantee that the Portfolio will be able to avoid a negative yield.

For the fiscal years indicated below, NTI voluntarily reimbursed expenses for the Portfolio as follows:

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PERFORMANCE INFORMATION

You may call 800-637-1380 to obtain the current 7-day yield and other performance information or visit northerntrust.com/institutional. Performance reflects expense limitations, fee waivers, if any, and reductions or expense reimbursements, as previously discussed in this SAI. If such expense limitations, fee waivers, reductions and expense reimbursements were not in place, the Portfolio’s performance would have been reduced. Any fees imposed by Northern Trust or other Servicing Agents on their customers in connection with investments in the Portfolio is not reflected in the Trust’s calculations of performance for the Portfolio.

The performance of a class of shares of the Portfolio may be compared to the performance of other money market funds with similar investment objectives and other relevant indices or to rankings prepared by independent services or other financial or industry publications that monitor the performance of mutual funds. For example, the performance of a class of shares may be compared to data prepared by iMoneyNet, Inc. or other independent mutual fund reporting services. Performance data as reported in national financial publications such as Money Magazine, Morningstar, Forbes, Barron’s, The Wall Street Journal and The New York Times, or in publications of a local or regional nature, also may be used in comparing the performance of a class of shares of the Portfolio.

From time to time, the Portfolio may advertise its “yields” and “effective yields.” Yield and effective yield are computed separately for each class of shares. Each class of shares has different fees and expenses, and consequently, may have different yields for the same period. These yield figures will fluctuate, are based on historical earnings and are not intended to indicate future performance. “Yield” refers to the net investment income generated by an investment in the Portfolio over a seven-day period identified in the advertisement. This net investment income is then “annualized.” That is, the amount of net investment income generated by the investment during that week is assumed to be generated each week over a 52-week period and is shown as a percentage of the investment.

In arriving at quotations as to “yield,” the Trust first determines the net change, exclusive of capital changes, during the seven-day period in the value of a hypothetical pre-existing account having a balance of one share at the beginning of the period, then divides such net change by the value of the account at the beginning of the period to obtain the base period return, and then multiplies the base period return by 365/7.

“Effective yield” is calculated similarly but, when annualized, the net investment income earned by an investment in the Portfolio is assumed to be reinvested. The “effective yield” will be slightly higher than the “yield” because of the compounding effect of this assumed reinvestment. The “effective yield” is computed by adding 1 to the base period return (calculated as above), raising the sum to a power equal to 365 divided by 7, and subtracting 1 from the result.

Quotations of yield, effective yield, tax-equivalent yield and tax-equivalent effective yield provided by the Trust are carried to at least the nearest hundredth of one percent. Any fees imposed by Northern Trust, its affiliates or financial intermediaries on their customers in connection with investments in the Portfolio are not reflected in the calculation of yields for the Portfolio. A money market portfolio also may quote, from time to time, total return in accordance with SEC regulations.

The Portfolio’s yields may not provide a basis for comparison with bank deposits and other investments which provide a fixed yield for a stated period of time. The Portfolio’s yields fluctuate, unlike bank deposits or other investments which pay a fixed yield for a stated period of time. The annualization of one week’s income is not necessarily indicative of future actual yields. Actual yields will depend on such variables as portfolio quality, average portfolio maturity, the type of portfolio instruments acquired, changes in money market interest rates, portfolio expenses and other factors. Yields are one basis investors may use to analyze a class of shares of the Portfolio as compared to comparable classes of shares of other money market funds and other investment vehicles.

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However, yields of other money market funds and other investment vehicles may not be comparable because of the foregoing variables, and differences in the methods used in valuing their portfolio instruments, computing NAV and determining yield. The Portfolio also may quote, from time to time, the total return of its Siebert Williams Shank shares in accordance with SEC regulations.

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NET ASSET VALUE

As stated in the Prospectus, the Treasury Portfolio operates as a “government money market fund” under Rule 2a-7 of the 1940 Act and seeks to maintain a NAV of $1.00 per share and, in this connection, values its instruments on the basis of amortized cost pursuant to Rule 2a-7 under the 1940 Act. This method values a security at its cost on the date of purchase and thereafter assumes a constant amortization to maturity of any discount or premium, regardless of the impact of fluctuating interest rates on the market value of the instrument. While this method provides certainty in valuation, it may result in periods during which value, as determined by amortized cost, is higher or lower than the price the Portfolio would receive if the Portfolio sold the instrument. During such periods, the yield to investors in the Portfolio may differ somewhat from that obtained in a similar entity, which uses available indications as to market value to value its portfolio instruments. For example, if the use of amortized cost resulted in a lower (higher) aggregate Portfolio value on a particular day, a prospective investor in the Portfolio would be able to obtain a somewhat higher (lower) yield and ownership interest than would result from investment in such similar entity and existing investors would receive less (more) investment income and ownership interest. However, the Trust expects that the procedures and limitations referred to in the following paragraphs of this section will tend to minimize the differences referred to above.

Under Rule 2a-7, the Board, in supervising the Trust’s operations and delegating special responsibilities involving portfolio management to the Investment Adviser, has established procedures that are intended, taking into account current market conditions and the Portfolio’s investment objective, to stabilize the NAV of the Portfolio, as computed for the purposes of purchases and redemptions, at $1.00 per share. The Trustees’ procedures include periodic monitoring of the difference (the “Market Value Difference”) between the amortized cost value per share and the NAV per share based upon available indications of market value. Available indications of market value used by the Trust consist of actual market quotations or appropriate substitutes, which reflect current market conditions and include (i) quotations or estimates of market value for individual portfolio instruments and/or (ii) values for individual portfolio instruments derived from market quotations relating to varying maturities of a class of money market instruments. In the event the Market Value Difference of a given Portfolio exceeds certain limits or NTI believes that the Market Value Difference may result in material dilution or other unfair results to investors or existing shareholders, the Trust will take action in accordance with the 1940 Act (e.g., selling portfolio instruments to shorten average portfolio maturity or to realize capital gains or losses, reducing or suspending shareholder income accruals, redeeming shares in-kind, or utilizing a NAV per share based upon available indications of market value which under such circumstances would vary from $1.00) to eliminate or reduce to the extent reasonably practicable any material dilution or other unfair results to investors or existing shareholders which might arise from Market Value Differences. In particular, if losses were sustained by the Portfolio, the number of outstanding shares might be reduced in order to maintain a NAV per share of $1.00. Such reduction would be effected by having each shareholder proportionately contribute to the Portfolio’s capital the necessary shares to restore such NAV per share. Each shareholder will be deemed to have agreed to such contribution in these circumstances by investing in the Portfolio.

Rule 2a-7 requires that the Portfolio limit its investments to instruments (i) that the Investment Adviser determines (pursuant to guidelines established by the Board) to present minimal credit risks; or (ii) are issued by other investment companies that are money market funds; or (iii) are U.S. government securities. The Rule also requires that the Portfolio maintain a dollar-weighted average portfolio maturity (not more than 60 days) and a dollar-weighted average portfolio maturity without regard to maturity shortening provisions applicable to variable and floating rate securities (also known as dollar-weighted average portfolio life) of 120 days or less appropriate to its policy of maintaining a stable NAV per share and precludes the purchase of any instrument deemed under the Rule to have a remaining maturity of more than 397 calendar days (as calculated pursuant to Rule 2a-7). Should the disposition of a portfolio security result in a dollar-weighted average portfolio maturity of more than 60 days, the Rule requires the Portfolio to invest its available cash in such a manner as to reduce such maturity to the prescribed limit as soon as reasonably practicable.

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The Portfolio is required to comply with SEC requirements with respect to the liquidity of the Portfolio’s investments. The Portfolio will not acquire any security other than a daily liquid asset unless, immediately following such purchase, at least 10% of its total assets would be invested in daily liquid assets. The Portfolio will not acquire any security other than a weekly liquid asset unless, immediately following such purchase, at least 30% of its total assets would be invested in “weekly liquid assets.” For these purposes, daily and weekly liquid assets are calculated as of the end of each business day. Daily liquid assets include: cash; direct obligations of the U.S. government; securities that will mature or are subject to a demand feature that is exercisable and payable within one business day; and amounts receivable and due unconditionally within one business day on pending sales of portfolio securities. Weekly liquid assets include: cash; direct obligations of the U.S. government; certain U.S. government agency discount notes without provision for the payment of interest with remaining maturities of 60 days or less; securities that will mature or are subject to a demand feature that is exercisable and payable within five business days; and amounts receivable and due unconditionally within five business days on pending sales of portfolio securities.

The time at which transactions and shares are priced and the time by which orders must be received may be changed in case of an emergency or if regular trading on the New York Stock Exchange is stopped at a time other than 4:00 p.m. Eastern Standard Time. The Trust reserves the right to reprocess purchase, redemption and exchange transactions that were processed at a NAV other than the Portfolio’s official closing NAV. For instance, if a pricing error is discovered that impacts the Portfolio’s NAV, the corrected NAV would be the official closing NAV and the erroneous NAV would be a NAV other than the Portfolio’s official closing NAV. Those transactions that were processed using the erroneous NAV may then be reprocessed using the official closing NAV.

The Portfolio may also close on days when the Federal Reserve Bank of New York (“New York Fed”) is open but the New York Stock Exchange is closed, such as Good Friday, and when the Securities Industry and Financial Markets Association (“SIFMA”) recommends that the bond markets close early, and the Portfolio reserves the right to close at or prior to the SIFMA recommended closing time. If the Portfolio does so, it will cease granting same day credit for purchase and redemption orders received at the Portfolio’s closing time and credit will be given on the next Business Day. The Trust reserves the right to advance the time by which purchase and redemption orders must be received for same business day credit as otherwise permitted by the SEC. In addition, the Portfolio may compute its NAV as of any time permitted pursuant to any exemption, order or statement of the SEC or its staff.

A Business Day is defined as each Monday through Friday that the New York Fed is open for business, except as noted below. The New York Fed is closed on the following national holidays: New Year’s Day, Martin Luther King, Jr. Day, Presidents’ Day, Memorial Day, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving Day and Christmas Day.

The Investment Adviser is not required to calculate the NAV of the Portfolio on days during which no shares are tendered to the Portfolio for redemption and no orders to purchase or sell shares are received by the Portfolio, or on days on which there is an insufficient degree of trading in the Portfolio’s portfolio securities for changes in the value of such securities to affect materially the NAV per share.

The Portfolio currently does not intend to avail itself of the ability to impose liquidity fees and/or redemption gates as permitted, under certain conditions, by Rule 2a-7. However, the Board reserves the right, with notice to shareholders, to change this policy with respect to the Portfolio, thereby permitting the Portfolio to impose such fees and gates in the future.

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TAXES

The following summarizes certain additional tax considerations generally affecting the Portfolio and its shareholders that are not described in the Prospectus. No attempt is made to present a detailed explanation of the tax treatment of the Portfolio or its shareholders, and the discussions here and in the Prospectus are not intended as a substitute for careful tax planning. Potential investors should consult their tax advisers with specific reference to their own tax situations.

The discussions of the federal tax consequences in the Prospectus and this SAI are based on the Code and the regulations issued under it, and court decisions and administrative interpretations, as in effect on the date of this SAI. Future legislative or administrative changes or court decisions may significantly alter the statements included herein, and any such changes or decisions may be retroactive.

FEDERAL—GENERAL INFORMATION

The Portfolio intends to qualify as a regulated investment company under Subchapter M of Subtitle A, Chapter 1 of the Code. As a regulated investment company, the Portfolio generally is exempt from federal income tax on its net investment income and realized capital gains which it distributes to shareholders. To qualify for treatment as a regulated investment company, it must meet three important tests each year.

First, the Portfolio must derive with respect to each taxable year at least 90% of its gross income from dividends, interest, certain payments with respect to securities loans, gains from the sale or other disposition of stock or securities or foreign currencies, other income derived with respect to the Portfolio’s business of investing in stock, securities or currencies, or net income derived from interests in qualified publicly traded partnerships.

Second, generally, at the close of each quarter of the Portfolio’s taxable year, at least 50% of the value of the Portfolio’s assets must consist of cash and cash items, U.S. government securities, securities of other regulated investment companies, and securities of other issuers as to which (a) the Portfolio has not invested more than 5% of the value of its total assets in securities of the issuer and (b) the Portfolio does not hold more than 10% of the outstanding voting securities of the issuer, and no more than 25% of the value of the Portfolio’s total assets may be invested in the securities of (1) any one issuer (other than U.S. government securities and securities of other regulated investment companies), (2) two or more issuers that the Portfolio controls and which are engaged in the same or similar trades or businesses or (3) one or more qualified publicly traded partnerships.

Third, the Portfolio must distribute an amount equal to at least the sum of 90% of its investment company taxable income (net investment income and the excess of net short-term capital gain over net long-term capital loss), before taking into account any deduction for dividends paid, and 90% of its tax-exempt income, if any, for the year.

The Portfolio intends to comply with these requirements. If the Portfolio were to fail to make sufficient distributions, it could be liable for corporate income tax and for excise tax in respect of the shortfall or, if the shortfall is large enough, the Portfolio could be disqualified as a regulated investment company. If for any taxable year the Portfolio were not to qualify as a regulated investment company, all its taxable income would be subject to tax at regular corporate rates without any deduction for distributions to shareholders. In that event, taxable shareholders would recognize dividend income on distributions (including distributions attributable to tax-exempt income) to the extent of the Portfolio’s current and accumulated earnings and profits, and corporate shareholders could be eligible for the dividends-received deduction.

The Code imposes a non-deductible 4% excise tax on regulated investment companies that fail to currently distribute an amount equal to specified percentages of their ordinary taxable income with certain modifications and capital gain net income (excess of capital gains over capital losses) by the end of each calendar year. The

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Portfolio intends to make sufficient distributions or deemed distributions of its ordinary taxable income and capital gain net income each calendar year to avoid liability for this excise tax.

For federal income tax purposes, the Portfolio is permitted to carry forward a net capital loss realized in its taxable years beginning before December 23, 2010 to offset its own capital gains, if any, during the eight years following the year of the loss. These amounts are available to be carried forward to offset future capital gains to the extent permitted by the Code and applicable tax regulations.

STATE AND LOCAL TAXES

Although the Portfolio expects to qualify as a “regulated investment company” and to be relieved of all or substantially all federal income taxes, depending upon the extent of its activities in states and localities in which its offices are maintained, in which its agents or independent contractors are located or in which it is otherwise deemed to be conducting business, the Portfolio may be subject to the tax laws of such states or localities.

Many states grant tax-free status to dividends paid to shareholders of a fund from interest income earned by that fund from direct obligations of the U.S. government, subject in some states to minimum investment requirements that must be met by the fund. Investments in securities issued by Ginnie Mae or Fannie Mae, bankers’ acceptances, commercial paper and repurchase agreements collateralized by U.S. Government securities do not generally qualify for tax-free treatment.

POTENTIAL PASS-THROUGH OF TAX CREDITS

If the Portfolio holds (directly or indirectly) one or more “tax credit bonds” (defined below) on one or more specified dates during the Portfolio’s taxable year, the Portfolio may elect for U.S. Federal income tax purposes to pass through to shareholders tax credits otherwise allowable to the Portfolio for that year with respect to such bonds. A tax credit bond is defined in the Code as a “qualified tax credit bond” (which includes a qualified forestry conservation bond, a new clean renewable energy bond, a qualified energy conservation bond, and a qualified zone academy bond, each of which must meet certain requirements specified in the Code), a “build America bond” (which includes certain qualified bonds issued before January 1, 2011) or certain other specified bonds. If the Portfolio were to make an election, a shareholder of the Portfolio would be required to include in income and would be entitled to claim as a tax credit an amount equal to a proportionate share of such credits. However, such tax credits are generally not refundable. There is no assurance that the Portfolio will elect to pass through any such income and credits. Certain limitations may apply on the extent to which the credit may be claimed. On December 22, 2017, the President signed into law H.R. 1, originally known as the “Tax Cuts and Jobs Act.” The law repeals the rules related to tax credit bonds and is effective for bonds issued after December 31, 2017, but does not affect the tax treatment of bonds issued prior to January 1, 2018.

The foregoing discussion is based on federal tax laws and regulations which are in effect on the date of this SAI. Such laws and regulations may be changed by legislative or administrative action. No attempt is made to present a detailed explanation of the tax treatment of the Portfolio or their shareholders, and the discussion here and in the Prospectus is not intended as a substitute for careful tax planning. Shareholders are advised to consult their tax advisors with specific reference to their own tax situation, including the application of state and local taxes.

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DESCRIPTION OF SHARES

The Trust Agreement permits the Board to issue an unlimited number of full and fractional shares of beneficial interest of one or more separate series representing interests in one or more investment portfolios. The Trustees of the Trust may hereafter create series in addition to the Trust’s five existing series, which represent interests in the Trust’s five respective portfolios, one of which is described in this SAI. The Trust Agreement also permits the Board to classify or reclassify any unissued shares into classes within a series. Pursuant to such authority, the Trustees have authorized the issuance of an unlimited number of shares of beneficial interest in four classes in the Portfolio: Shares, Service Shares, Premier Shares, and Siebert Williams Shank Shares. Shares, Services Shares, and Premier Shares are described in a separate prospectus and SAI.

The Trustees may appoint separate Trustees with respect to one or more series or classes of the Trust’s shares (the “Series Trustees”). To the extent provided by the Trustees in the appointment of Series Trustees, Series Trustees: (i) may, but are not required to, serve as Trustees of the Trust or any other series or class of the Trust; (ii) may have, to the exclusion of any other Trustee of the Trust, all the powers and authorities of Trustees under the Trust Agreement with respect to such series or class; and/or (iii) may have no power or authority with respect to any other series or class. There are currently no Series Trustees for the Trust.

Under the terms of the Trust Agreement, each share of the Portfolio is without par value, which represents a proportionate interest in the particular Portfolio with each other share of its class in the same Portfolio and is entitled to such dividends and distributions out of the income belonging to the Portfolio as are declared by the Trustees. Upon any liquidation of the Portfolio, shareholders of each class of the Portfolio are entitled to share pro rata in the net assets belonging to that class available for distribution. Shares do not have any preemptive or conversion rights. The right of redemption is described under “Account Policies and Other Information” in the Prospectus. In addition, pursuant to the terms of the 1940 Act, the right of a shareholder to redeem shares and the date of payment by the Portfolio may be suspended for more than seven days (i) for any period during which the New York Stock Exchange is closed, other than the customary weekends or holidays, or trading in the markets the Portfolio normally utilizes is closed or is restricted as determined by the SEC, (ii) during any emergency, as determined by the SEC, as a result of which it is not reasonably practicable for the Portfolio to dispose of instruments owned by it or fairly to determine the value of its net assets, or (iii) for such other period as the SEC may by order permit for the protection of the shareholders of the Portfolio. The Trust also may suspend or postpone the recordation of the transfer of its shares upon the occurrence of any of the foregoing conditions. In addition, shares of the Portfolio are redeemable at the unilateral option of the Trust. Shares when issued as described in the Prospectus are validly issued, fully paid and nonassessable, except as stated below. In the interests of economy and convenience, certificates representing shares of the Portfolio are not issued.

The proceeds received by the Portfolio for each issue or sale of its shares, and all net investment income, realized and unrealized gain and proceeds thereof, subject only to the rights of creditors, will be specifically allocated to and constitute the underlying assets of that Portfolio. The underlying assets of the Portfolio will be segregated on the books of account, and will be charged with the liabilities in respect to that Portfolio and with a share of the general liabilities of the Trust. Expenses with respect to the Portfolio and the other portfolios of the Trust normally are allocated in proportion to the NAV of the respective portfolios except where allocations of direct expenses can otherwise be fairly made.

NOTICE: Under Section 72.1021(a) of the Texas Property Code, initial investors in the Portfolio who are Texas residents may designate a representative to receive notices of abandoned property in connection with Portfolio shares. Texas shareholders who wish to appoint a representative should notify the Trust’s Transfer Agent by writing to the Northern Institutional Funds Center, P.O. Box 75986, Chicago, Illinois 60675-5986 or by calling 800-637-1380 to obtain a form for providing written notice to the Trust.

The Portfolio and other portfolios of the Trust entitled to vote on a matter will vote in the aggregate and not by portfolio, except as required by law or when the matter to be voted on affects only the interests of shareholders of a particular portfolio.

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Rule 18f-2 under the 1940 Act provides that any matter required by the provisions of the 1940 Act or applicable state law, or otherwise, to be submitted to the holders of the outstanding voting securities of an investment company such as the Trust shall not be deemed to have been effectively acted upon unless approved by the holders of a majority of the outstanding shares of each investment portfolio affected by such matter. Rule 18f-2 further provides that an investment portfolio shall be deemed to be affected by a matter unless the interests of each investment portfolio in the matter are substantially identical or the matter does not affect any interest of the investment portfolio. Under the Rule, the approval of an investment advisory agreement or any change in a fundamental investment policy would be effectively acted upon with respect to an investment portfolio only if approved by a majority of the outstanding shares of such investment portfolio. However, the Rule also provides that the ratification of the appointment of independent accountants, the approval of principal underwriting contracts and the election of Trustees are exempt from the separate voting requirements stated above. In addition, shareholders of each of the classes of an investment portfolio have equal voting rights except that only shares of the particular class(es) affected by the matter will be entitled to vote on such matters (e.g., matters relating to shareholder servicing expenses and transfer agent fees that are payable by that class). The Trust is not required to hold annual meetings of shareholders and does not intend to hold such meetings. In the event that a meeting of shareholders is held, each share of the Trust will be entitled, as determined by the Trustees without the vote or consent of shareholders, either to one vote for each share (and proportionate fractional votes for fractional shares held) or to one vote for each dollar of NAV represented by such shares on all matters presented to shareholders, including the election of Trustees (this method of voting being referred to as “dollar-based voting”). However, to the extent required by the 1940 Act or otherwise determined by the Trustees, series and classes of the Trust will vote separately from each other. Shareholders of the Trust do not have cumulative voting rights in the election of Trustees and, accordingly, the holders of more than 50% of the aggregate voting power of the Trust may elect all of the Trustees, irrespective of the vote of the other shareholders. Meetings of shareholders of the Trust, or any series or class thereof, may be called by the Trustees, certain officers or upon the written request of holders of 10% or more of the shares entitled to vote at such meeting. The power to call a vote with respect to shareholders of the Portfolio is vested exclusively with the Board. To the extent required by law, the Trust will assist in shareholder communications in connection with a meeting called by shareholders. The shareholders of the Trust will have voting rights only with respect to the limited number of matters specified in the Trust Agreement and such other matters as the Trustees may determine or may be required by law.

The Trust Agreement authorizes the Trustees, without shareholder approval (except as stated in the next paragraph), to cause the Trust, or any series thereof, to merge or consolidate with any corporation, association, trust or other organization or sell or exchange all or substantially all of the property belonging to the Trust, or any series thereof. In addition, the Trustees, without shareholder approval, may adopt a “master-feeder” structure by investing substantially all of the assets of a series of the Trust in the securities of another open-end investment company or pooled portfolio.

The Trust Agreement also authorizes the Trustees, in connection with the merger, consolidation, termination or other reorganization of the Trust or any series or class, to classify the shareholders of any class into one or more separate groups and to provide for the different treatment of shares held by the different groups, provided that such merger, consolidation, termination or other reorganization is approved by a majority of the outstanding voting securities (as defined in the 1940 Act) of each group of shareholders that are so classified.

The Board may not, without the affirmative vote of the holders of a majority of the outstanding shares of the Trust, amend or otherwise supplement the Trust Agreement or amend and restate a trust investment to reduce the rights, duties, powers, authorities and responsibilities of the Trustees, except to the extent such action does not violate the 1940 Act. Subject to the foregoing, the Trust Agreement permits the Trustees to amend the Trust

Agreement without a shareholder vote. However, shareholders of the Trust have the right to vote on any amendment: (i) that would adversely affect the voting rights of shareholders; (ii) that is required by law to be approved by shareholders; (iii) that would amend the voting provisions of the Trust Agreement; or (iv) that the Trustees determine to submit to shareholders.

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The Trust Agreement permits the termination of the Trust or of any series or class of the Trust: (i) by a majority of the affected shareholders at a meeting of shareholders of the Trust, series or class; or (ii) by a majority of the Trustees without shareholder approval if the Trustees determine that such action is in the best interest of the Trust or its shareholders. The factors and events that the Trustees may take into account in making such determination include: (i) the inability of the Trust or any series or class to maintain its assets at an appropriate size; (ii) changes in laws or regulations governing the Trust, or any series or class thereof, or affecting assets of the type in which it invests; or (iii) economic developments or trends having a significant adverse impact on their business or operations.

Under the Delaware Statutory Trust Act (the “Delaware Act”), shareholders are not personally liable for obligations of the Trust. The Delaware Act entitles shareholders of the Trust to the same limitation of liability as is available to shareholders of private for-profit corporations. However, no similar statutory or other authority limiting statutory trust shareholder liability exists in many other states. As a result, to the extent that the Trust or a shareholder is subject to the jurisdiction of courts in such other states, those courts may not apply Delaware law and may subject the shareholders to liability. To offset this risk, the Trust Agreement: (i) contains an express disclaimer of shareholder liability for acts or obligations of the Trust and requires that notice of such disclaimer be given in each agreement, obligation and instrument entered into or executed by the Trust or its Trustees and (ii) provides for indemnification out of the property of the applicable series of the Trust of any shareholder held personally liable for the obligations of the Trust solely by reason of being or having been a shareholder and not because of the shareholder’s acts or omissions or for some other reason. Thus, the risk of a shareholder incurring financial loss beyond his or her investment because of shareholder liability is limited to circumstances in which all of the following factors are present: (i) a court refuses to apply Delaware law; (ii) the liability arises under tort law or, if not, no contractual limitation of liability is in effect; and (iii) the applicable series of the Trust is unable to meet its obligations.

The Trust Agreement provides that the Trustees will not be liable to any person other than the Trust or a shareholder and that a Trustee will not be liable for any act as a Trustee. However, nothing in the Trust Agreement protects a Trustee against any liability to which he or she would otherwise be subject by reason of willful misfeasance, bad faith, gross negligence or reckless disregard of the duties involved in the conduct of his or her office. The Trust Agreement provides for indemnification of Trustees, officers and agents of the Trust unless the recipient is liable by reason of willful misfeasance, bad faith, gross negligence or reckless disregard of the duties involved in the conduct of such person’s office.

The Trust Agreement provides that each shareholder, by virtue of becoming such, will be held to have expressly assented and agreed to the terms of the Trust Agreement and to have become a party thereto.

In addition to the requirements of Delaware law, the Trust Agreement provides that a shareholder of the Trust may bring a derivative action on behalf of the Trust only if the following conditions are met: (i) shareholders eligible to bring such derivative action under Delaware law who hold at least 10% of the outstanding shares of the Trust, or 10% of the outstanding shares of the series or class to which such action relates, must join in the request for the Trustees to commence such action; and (ii) the Trustees must be afforded a reasonable amount of time to consider such shareholder request and to investigate the basis of such claim. The Trust Agreement also provides that no person, other than the Trustees, who is not a shareholder of a particular series or class shall be entitled to bring any derivative action, suit or other proceeding on behalf of or with respect to such series or class. The Trustees will be entitled to retain counsel or other advisers in considering the merits of the request and may require an undertaking by the shareholders making such request to reimburse the Trust for the expense of any such advisers in the event that the Trustees determine not to bring such action.

The term “majority of the outstanding shares” of either the Trust or the Portfolio means, with respect to the approval of an investment advisory agreement or a change in a fundamental investment policy, the vote of the lesser of (i) 67% or more of the shares of the Trust or such Portfolio present at a meeting, if the holders of more than 50% of the outstanding shares of the Trust or such Portfolio are present or represented by proxy, or (ii) more than 50% of the outstanding shares of the Trust or such Portfolio.

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The Trust’s by-laws state that, unless the Trust consents in writing to the selection of an alternative forum, the sole and exclusive forums for any Shareholder (including a beneficial owner) to bring (i) any derivative action or proceeding brought on behalf of the Trust, (ii) any action asserting a claim or breach of a fiduciary duty owed by any Trustee, officer or employee, if any, of the Trust to the Trust or the Trust’s Shareholders, (iii) any action asserting a claim against the Trust, its Trustees, officers or employees, if any, arising pursuant to any provision of the Delaware Statutory Trust Act or the Trust’s Trust Instrument or by-law; or (iv) any action asserting a claim against the Trust, its Trustees, officers or employees, if any, governed by the internal affairs doctrine, shall be a state or federal court located within the State of Delaware. The Trust’s by-laws also state that any persons or entity that is a shareholder of the Trust shall be deemed to have notice of and consented to the foregoing provisions of the Trust’s by-laws.

As of November 5, 2021, TNTC and its affiliates held of record outstanding shares of the Portfolio as agent, custodian, trustee or investment adviser on behalf of their customers. The amount of shares held of record may be more than 25%. As of November 5, 2021, the Trust is not aware of any particular shareholder holding more than 25% of the Portfolio’s shares. To the extent that any shareholder is the beneficial owner of more than 25% of the outstanding shares of the Portfolio, such shareholder may be deemed a “control person” of the Portfolio for purposes of the 1940 Act. Prior to the date of this SAI, Siebert Williams Shank shares of the Portfolio had not yet commenced operations; therefore, there were no shareholders of the Siebert Williams Shank shares.

As of November 5, 2021, the Trust’s Trustees and officers as a group owned beneficially less than 1% of the outstanding shares of each class of the Portfolio.

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FINANCIAL STATEMENTS

The audited financial statements of the Portfolio and related report of Deloitte  & Touche LLP, an independent registered public accounting firm, contained in the Annual Report to the Portfolio’s shareholders for the fiscal year ended November  30, 2020 (the “Annual Report”), as well as the unaudited financial statements of the Portfolio contained in the Semiannual Report to the Portfolio’s shareholders for the six-month period ended May 31, 2021 (the “Semiannual Report”) are hereby incorporated by reference herein. Information in the financial statements for periods prior to the fiscal year ended November 30, 2017 were audited by the Portfolio’s former independent registered public accounting firm. No other parts of the Annual Report, including without limitation, “Management’s Discussion of Portfolio Performance,” or the Semiannual Report are incorporated by reference herein. Copies of the Portfolio’s Annual Report and Semiannual Report may be obtained upon request and without charge, from the Transfer Agent by writing to the Northern Institutional Funds Center, P.O. Box 75986, Chicago, Illinois 60675-5986 or by calling 800-637-1380 (toll-free).

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OTHER INFORMATION

Statements contained in the Prospectus or in this SAI as to the contents of any contract or other documents referred to are not necessarily complete, and in each instance reference is made to the copy of such contract or other document filed as an exhibit to the Registration Statement of which the Prospectus and this SAI form a part, each such statement being qualified in all respects by such reference. The Registration Statement, including the exhibits filed therewith, may be examined at the office of the SEC in Washington, D.C. or on the SEC’s website at sec.gov.

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APPENDIX A

DESCRIPTION OF SECURITIES RATINGS

Short-Term Credit Ratings

An S&P Global Ratings short-term issue credit rating is generally assigned to those obligations considered short-term in the relevant market. The following summarizes the rating categories used by S&P Global Ratings for short-term issues:

“A-1”—A short-term obligation rated “A-1” is rated in the highest category by S&P Global Ratings. The obligor’s capacity to meet its financial commitments on the obligation is strong. Within this category, certain obligations are designated with a plus sign (+). This indicates that the obligor’s capacity to meet its financial commitment on these obligations is extremely strong.

“A-2”—A short-term obligation rated “A-2” is somewhat more susceptible to the adverse effects of changes in circumstances and economic conditions than obligations in higher rating categories. However, the obligor’s capacity to meet its financial commitments on the obligation is satisfactory.

“A-3”—A short-term obligation rated “A-3” exhibits adequate protection parameters. However, adverse economic conditions or changing circumstances are more likely to weaken an obligor’s capacity to meet its financial commitments on the obligation.

“B”—A short-term obligation rated “B” is regarded as vulnerable and has significant speculative characteristics. The obligor currently has the capacity to meet its financial commitments; however, it faces major ongoing uncertainties that could lead to the obligor’s inadequate capacity to meet its financial commitments.

“C”—A short-term obligation rated “C” is currently vulnerable to nonpayment and is dependent upon favorable business, financial, and economic conditions for the obligor to meet its financial commitments on the obligation.

“D”—A short-term obligation rated “D” is in default or in breach of an imputed promise. For non-hybrid capital instruments, the “D” rating category is used when payments on an obligation are not made on the date due, unless S&P Global Ratings believes that such payments will be made within any stated grace period. However, any stated grace period longer than five business days will be treated as five business days. The “D” rating also will be used upon the filing of a bankruptcy petition or the taking of a similar action and where default on an obligation is a virtual certainty, for example due to automatic stay provisions. A rating on an obligation is lowered to “D” if it is subject to a distressed debt restructuring.

Local Currency and Foreign Currency Ratings—S&P Global Ratings’ issuer credit ratings make a distinction between foreign currency ratings and local currency ratings. A foreign currency rating on an issuer can differ from the local currency rating on it when the obligor has a different capacity to meet its obligations denominated in its local currency, versus obligations denominated in a foreign currency.

“NR”—This indicates that a rating has not been assigned or is no longer assigned.

Moody’s Investors Service (“Moody’s”) short-term ratings are forward-looking opinions of the relative credit risks of financial obligations with an original maturity of thirteen months or less and reflect both on the likelihood of a default or impairment on contractual financial obligations and the expected financial loss suffered in the event of default or impairment.

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Moody’s employs the following designations to indicate the relative repayment ability of rated issuers:

“P-1”—Issuers (or supporting institutions) rated Prime-1 reflect a superior ability to repay short-term obligations.

“P-2”—Issuers (or supporting institutions) rated Prime-2 reflect a strong ability to repay short-term obligations.

“P-3”—Issuers (or supporting institutions) rated Prime-3 reflect an acceptable ability to repay short-term obligations.

“NP”—Issuers (or supporting institutions) rated Not Prime do not fall within any of the Prime rating categories.

“NR”—Is assigned to an unrated issuer.

Fitch, Inc. / Fitch Ratings Ltd. (“Fitch”) short-term issuer or obligation rating is based in all cases on the short-term vulnerability to default of the rated entity and relates to the capacity to meet financial obligations in accordance with the documentation governing the relevant obligation. Short-term deposit ratings may be adjusted for loss severity. Short-term ratings are assigned to obligations whose initial maturity is viewed as “short-term” based on market convention¹. Typically, this means up to 13 months for corporate, sovereign, and structured obligations and up to 36 months for obligations in U.S. public finance markets. The following summarizes the rating categories used by Fitch for short-term obligations:

“F1”—Securities possess the highest short-term credit quality. This designation indicates the strongest intrinsic capacity for timely payment of financial commitments; may have an added “+” to denote any exceptionally strong credit feature.

“F2”—Securities possess good short-term credit quality. This designation indicates good intrinsic capacity for timely payment of financial commitments.

“F3”—Securities possess fair short-term credit quality. This designation indicates that the intrinsic capacity for timely payment of financial commitments is adequate.

“B”—Securities possess speculative short-term credit quality. This designation indicates minimal capacity for timely payment of financial commitments, plus heightened vulnerability to near term adverse changes in financial and economic conditions.

“C”—Securities possess high short-term default risk. Default is a real possibility.

“RD”—Restricted default. Indicates an entity that has defaulted on one or more of its financial commitments, although it continues to meet other financial obligations. Typically applicable to entity ratings only.

“D”—Default. Indicates a broad-based default event for an entity, or the default of a short-term obligation.

Plus (+) or minus (-)—The “F1” rating may be modified by the addition of a plus (+) or minus (-) sign to show the relative status within that major rating category.

“NR”—Is assigned to an unrated issue of a rated issuer.

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The DBRS^® Morningstar^® Ratings Limited (“DBRS Morningstar”) short-term debt rating scale provides an opinion on the risk that an issuer will not meet its short-term financial obligations in a timely manner. Ratings are based on quantitative and qualitative considerations relevant to the issuer and the relative ranking of claims. The R-1 and R-2 rating categories are further denoted by the sub-categories “(high)”, “(middle)”, and “(low)”. The following summarizes the ratings used by DBRS Morningstar for commercial paper and short-term debt: “R-1 (high)”—Short-term debt rated “R-1 (high)” is of the highest credit quality. The capacity for the payment of short-term financial obligations as they fall due is exceptionally high. Unlikely to be adversely affected by future events.

“R-1 (middle)”—Short-term debt rated “R-1 (middle)” is of superior credit quality. The capacity for the payment of short-term financial obligations as they fall due is very high. Differs from “R-1 (high)” by a relatively modest degree. Unlikely to be significantly vulnerable to future events.

“R-1 (low)”—Short-term debt rated “R-1 (low)” is of good credit quality. The capacity for the payment of short-term financial obligations as they fall due is substantial. Overall strength is not as favorable as higher rating categories. May be vulnerable to future events, but qualifying negative factors are considered manageable.

“R-2 (high)”—Short-term debt rated “R-2 (high)” is considered to be at the upper end of adequate credit quality. The capacity for the payment of short-term financial obligations as they fall due is acceptable. May be vulnerable to future events.

“R-2 (middle)”—Short-term debt rated “R-2 (middle)” is considered to be of adequate credit quality. The capacity for the payment of short-term financial obligations as they fall due is acceptable. May be vulnerable to future events or may be exposed to other factors that could reduce credit quality.

“R-2 (low)”—Short-term debt rated “R-2 (low)” is considered to be at the lower end of adequate credit quality. The capacity for the payment of short-term financial obligations as they fall due is acceptable. May be vulnerable to future events. A number of challenges are present that could affect the issuer’s ability to meet such obligations.

“R-3”—Short-term debt rated “R-3” is considered to be at the lowest end of adequate credit quality. There is a capacity for the payment of short-term financial obligations as they fall due. May be vulnerable to future events and the certainty of meeting such obligations could be impacted by a variety of developments.

“R-4”—Short-term debt rated “R-4” is considered to be of speculative credit quality. The capacity for the payment of short-term financial obligations as they fall due is uncertain.

“R-5”—Short-term debt rated “R-5” is considered to be of highly speculative credit quality. There is a high level of uncertainty as to the capacity to meet short-term financial obligations as they fall due.

“D”—Short-term debt rated “D” is assigned when the issuer has filed under any applicable bankruptcy, insolvency or winding up statute or there is a failure to satisfy an obligation after the exhaustion of grace periods, a downgrade to “D” may occur. DBRS Morningstar may also use “SD” (Selective Default) in cases where only some securities are impacted, such as the case of a “distressed exchange”.

Long-Term Credit Ratings

The following summarizes the ratings used by S&P Global Ratings for long-term issues:

“AAA”—An obligation rated “AAA” has the highest rating assigned by S&P Global Ratings. The obligor’s capacity to meet its financial commitments on the obligation is extremely strong.

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“AA”—An obligation rated “AA” differs from the highest-rated obligations only to a small degree. The obligor’s capacity to meet its financial commitments on the obligation is very strong.

“A”—An obligation rated “A” is somewhat more susceptible to the adverse effects of changes in circumstances and economic conditions than obligations in higher-rated categories. However, the obligor’s capacity to meet its financial commitments on the obligation is still strong.

“BBB”—An obligation rated “BBB” exhibits adequate protection parameters. However, adverse economic conditions or changing circumstances are more likely to weaken the obligor’s capacity to meet its financial commitments on the obligation.

“BB,” “B,” “CCC,” “CC” and “C”—Obligations rated “BB,” “B,” “CCC,” “CC” and “C” are regarded as having significant speculative characteristics. “BB” indicates the least degree of speculation and “C” the highest. While such obligations will likely have some quality and protective characteristics, these may be outweighed by large uncertainties or major exposure to adverse conditions.

“BB”—An obligation rated “BB” is less vulnerable to nonpayment than other speculative issues. However, it faces major ongoing uncertainties or exposure to adverse business, financial, or economic conditions that could lead to the obligor’s inadequate capacity to meet its financial commitments on the obligation.

“B”—An obligation rated “B” is more vulnerable to nonpayment than obligations rated “BB”, but the obligor currently has the capacity to meet its financial commitments on the obligation. Adverse business, financial, or economic conditions will likely impair the obligor’s capacity or willingness to meet its financial commitments on the obligation.

“CCC”—An obligation rated “CCC” is currently vulnerable to nonpayment and is dependent upon favorable business, financial, and economic conditions for the obligor to meet its financial commitments on the obligation. In the event of adverse business, financial, or economic conditions, the obligor is not likely to have the capacity to meet its financial commitments on the obligation.

“CC”—An obligation rated “CC” is currently highly vulnerable to nonpayment. The “CC” rating is used when a default has not yet occurred but S&P Global Ratings expects default to be a virtual certainty, regardless of the anticipated time to default.

“C”—An obligation rated “C” is currently highly vulnerable to nonpayment, and the obligation is expected to have lower relative seniority or lower ultimate recovery compared with obligations that are rated higher.

“D”—An obligation rated “D” is in default or in breach of an imputed promise. For non-hybrid capital instruments, the “D” rating category is used when payments on an obligation are not made on the date due, unless S&P Global Ratings believes that such payments will be made within five business days in the absence of a stated grace period or within the earlier of the stated grace period or 30 calendar days. The “D” rating also will be used upon the filing of a bankruptcy petition or the taking of similar action and where default on an obligation is a virtual certainty, for example due to automatic stay provisions. A rating on an obligation is lowered to “D” if it is subject to a distressed debt restructuring

Plus (+) or minus (-)—The ratings from “AA” to “CCC” may be modified by the addition of a plus (+) or minus (-) sign to show relative standing within the rating categories.

“NR”—This indicates that a rating has not been assigned, or is no longer assigned.

Local Currency and Foreign Currency Ratings—S&P Global Ratings’ issuer credit ratings make a distinction between foreign currency ratings and local currency ratings. A foreign currency rating on an issuer

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can differ from the local currency rating on it when the obligor has a different capacity to meet its obligations denominated in its local currency, versus obligations denominated in a foreign currency.

Moody’s long-term ratings are forward-looking opinions of the relative credit risks of financial obligations with an original maturity of one year or more. Such ratings reflect both on the likelihood of default or impairment on contractual financial obligations and the expected financial loss suffered in the event of default or impairment. The following summarizes the ratings used by Moody’s for long-term debt:

“Aaa”—Obligations rated “Aaa” are judged to be of the highest quality, subject to the lowest level of credit risk.

“Aa”—Obligations rated “Aa” are judged to be of high quality and are subject to very low credit risk. “A”—Obligations rated “A” are judged to be upper-medium grade and are subject to low credit risk.

“Baa”—Obligations rated “Baa” are judged to be medium-grade and subject to moderate credit risk and as such may possess certain speculative characteristics.

“Ba”—Obligations rated “Ba” are judged to be speculative and are subject to substantial credit risk. “B”—Obligations rated “B” are considered speculative and are subject to high credit risk.

“Caa”—Obligations rated “Caa” are judged to be speculative of poor standing and are subject to very high credit risk.

“Ca”—Obligations rated “Ca” are highly speculative and are likely in, or very near, default, with some prospect of recovery of principal and interest.

“C”—Obligations rated “C” are the lowest rated and are typically in default, with little prospect for recovery of principal or interest.

Note: Moody’s appends numerical modifiers 1, 2, and 3 to each generic rating classification from “Aa” through “Caa.” The modifier 1 indicates that the obligation ranks in the higher end of its generic rating category; the modifier 2 indicates a mid-range ranking; and the modifier 3 indicates a ranking in the lower end of that generic rating category.

“NR”—Is assigned to unrated obligations.

The following summarizes long-term ratings used by Fitch:

“AAA”—Securities considered to be of the highest credit quality. “AAA” ratings denote the lowest expectation of credit risk. They are assigned only in cases of exceptionally strong capacity for payment of financial commitments. This capacity is highly unlikely to be adversely affected by foreseeable events.

“AA”—Securities considered to be of very high credit quality. “AA” ratings denote expectations of very low credit risk. They indicate very strong capacity for payment of financial commitments. This capacity is not significantly vulnerable to foreseeable events.

“A”—Securities considered to be of high credit quality. “A” ratings denote expectations of low credit risk. The capacity for payment of financial commitments is considered strong. This capacity may, nevertheless, be more vulnerable to adverse business or economic conditions than is the case for higher ratings.

“BBB”—Securities considered to be of good credit quality. “BBB” ratings indicate that expectations of credit risk are currently low. The capacity for payment of financial commitments is considered adequate, but adverse business or economic conditions are more likely to impair this capacity.

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“BB”—Securities considered to be speculative. “BB” ratings indicate that there is an elevated vulnerability to credit risk, particularly in the event of adverse changes in business or economic conditions over time; however, business or financial alternatives may be available to allow financial commitments to be met.

“B”—Securities considered to be highly speculative. “B” ratings indicate that material credit risk is present “CCC”—A “CCC” rating indicates that substantial credit risk is present.

“CC”—A “CC” rating indicates very high levels of credit risk.

“C”—A “C” rating indicates exceptionally high levels of credit risk.

Defaulted obligations typically are not assigned “RD” or “D” ratings but are instead rated in the “CCC” to “C” rating categories, depending on their recovery prospects and other relevant characteristics. Fitch believes that this approach better aligns obligations that have comparable overall expected loss but varying vulnerability to default and loss.

Plus (+) or minus (-) may be appended to a rating to denote relative status within major rating categories. Such suffixes are not added to the “AAA” obligation rating category, or to corporate finance obligation ratings in the categories below “CCC”.

“NR”—Is assigned to an unrated issue of a rated issuer.

The DBRS Morningstar long-term rating scale provides an opinion on the risk of default. That is, the risk that an issuer will fail to satisfy its financial obligations in accordance with the terms under which an obligation has been issued. Ratings are based on quantitative and qualitative considerations relevant to the issuer, and the relative ranking of claims. All rating categories other than AAA and D also contain subcategories “(high)” and “(low)”. The absence of either a “(high)” or “(low)” designation indicates the rating is in the middle of the category. The following summarizes the ratings used by DBRS Morningstar for long-term debt:

“AAA”—Long-term debt rated “AAA” is of the highest credit quality. The capacity for the payment of financial obligations is exceptionally high and unlikely to be adversely affected by future events.

“AA”—Long-term debt rated “AA” is of superior credit quality. The capacity for the payment of financial obligations is considered high. Credit quality differs from “AAA” only to a small degree. Unlikely to be significantly vulnerable to future events.

“A”—Long-term debt rated “A” is of good credit quality. The capacity for the payment of financial obligations is substantial, but of lesser credit quality than “AA.” May be vulnerable to future events, but qualifying negative factors are considered manageable.

“BBB”—Long-term debt rated “BBB” is of adequate credit quality. The capacity for the payment of financial obligations is considered acceptable. May be vulnerable to future events.

“BB”—Long-term debt rated “BB” is of speculative, non-investment grade credit quality. The capacity for the payment of financial obligations is uncertain. Vulnerable to future events.

“B”—Long-term debt rated “B” is of highly speculative credit quality. There is a high level of uncertainty as to the capacity to meet financial obligations.

“CCC”, “CC” and “C”—Long-term debt rated in any of these categories is of very highly speculative credit quality. In danger of defaulting on financial obligations. There is little difference between these three categories, although “CC” and “C” ratings are normally applied to obligations that are seen as highly likely to default, or

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subordinated to obligations rated in the “CCC” to “B” range. Obligations in respect of which default has not technically taken place but is considered inevitable may be rated in the “C” category.

“D”—A security rated “D” is assigned when the issuer has filed under any applicable bankruptcy, insolvency or winding up statute or there is a failure to satisfy an obligation after the exhaustion of grace periods, a downgrade to “D” may occur. DBRS Morningstar may also use “SD” (Selective Default) in cases where only some securities are impacted, such as the case of a “distressed exchange”.

Municipal Note Ratings

An S&P Global Ratings U.S. municipal note rating reflects S&P Global Ratings’ opinion about the liquidity factors and market access risks unique to the notes. Notes due in three years or less will likely receive a note rating. Notes with an original maturity of more than three years will most likely receive a long-term debt rating. In determining which type of rating, if any, to assign, S&P Global Ratings’ analysis will review the following considerations:

Municipal Short-Term Note rating symbols are as follows:

“SP-1”—A municipal note rated “SP-1” exhibits a strong capacity to pay principal and interest. An issue determined to possess a very strong capacity to pay debt service is given a plus (+) designation.

“SP-2”—A municipal note rated “SP-2” exhibits a satisfactory capacity to pay principal and interest, with some vulnerability to adverse financial and economic changes over the term of the notes.

“SP-3”—A municipal note rated “SP-3” exhibits a speculative capacity to pay principal and interest. “D”—This rating is assigned upon failure to pay the note when due, completion of a distressed debt restructuring, or the filing of a bankruptcy petition or the taking of similar action and where default on an obligation is a virtual certainty, for example due to automatic stay provisions.

Moody’s uses the global short-term Prime rating scale (listed above under Short-Term Credit Ratings) for commercial paper issued by U.S. municipalities and nonprofits. These commercial paper programs may be backed by external letters of credit or liquidity facilities, or by an issuer’s self-liquidity.

For other short-term municipal obligations, Moody’s uses one of two other short-term rating scales, the Municipal Investment Grade (“MIG”) and Variable Municipal Investment Grade (“VMIG”) scales provided below.

Moody’s uses the MIG scale for U.S. municipal cash flow notes, bond anticipation notes and certain other short-term obligations, which typically mature in three years or less. Under certain circumstances, Moody’s uses the MIG scale for bond anticipation notes with maturities of up to five years.

MIG Scale

“MIG-1”—This designation denotes superior credit quality. Excellent protection is afforded by established cash flows, highly reliable liquidity support, or demonstrated broad-based access to the market for refinancing.

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“MIG-2”—This designation denotes strong credit quality. Margins of protection are ample, although not as large as in the preceding group.

“MIG-3”—This designation denotes acceptable credit quality. Liquidity and cash-flow protection may be narrow, and market access for refinancing is likely to be less well-established.

“SG”—This designation denotes speculative-grade credit quality. Debt instruments in this category may lack sufficient margins of protection.

“NR”—Is assigned to an unrated obligation.

In the case of variable rate demand obligations (“VRDOs”), a two-component rating is assigned. The components are a long-term rating and a short-term demand obligation rating. The long-term rating addresses the issuer’s ability to meet scheduled principal and interest payments. The short-term demand obligation rating addresses the ability of the issuer or the liquidity provider to make payments associated with the purchase-price-upon demand feature (“demand feature”) of the VRDO. The short-term demand obligation rating uses the VMIG scale. VMIG ratings with liquidity support use as an input the short-term Counterparty Risk Assessment of the support provider, or the long-term rating of the underlying obligor in the absence of third party liquidity support. Transitions of VMIG ratings of demand obligations with conditional liquidity support differ from transitions on the Prime scale to reflect the risk that external liquidity support will terminate if the issuer’s long-term rating drops below investment grade.

Moody’s typically assigns the VMIG short-term demand obligation rating if the frequency of the demand feature is less than every three years. If the frequency of the demand feature is less than three years but the purchase price is payable only with remarketing proceeds, the short-term demand obligation rating is “NR”.

“VMIG-1”—This designation denotes superior credit quality. Excellent protection is afforded by the superior short-term credit strength of the liquidity provider and structural and legal protections that ensure the timely payment of purchase price upon demand.

“VMIG-2”—This designation denotes strong credit quality. Good protection is afforded by the strong short-term credit strength of the liquidity provider and structural and legal protections that ensure the timely payment of purchase price upon demand.

“VMIG-3”—This designation denotes acceptable credit quality. Adequate protection is afforded by the satisfactory short-term credit strength of the liquidity provider and structural and legal protections that ensure the timely payment of purchase price upon demand.

“SG”—This designation denotes speculative-grade credit quality. Demand features rated in this category may be supported by a liquidity provider that does not have a sufficiently strong short-term rating or may lack the structural and/or legal protections necessary to ensure the timely payment of purchase price upon demand.

“NR”—Is assigned to an unrated obligation.

About Credit Ratings

An S&P Global Ratings issue credit rating is a forward-looking opinion about the creditworthiness of an obligor with respect to a specific financial obligation, a specific class of financial obligations, or a specific financial program (including ratings on medium-term note programs and commercial paper programs). It takes into consideration the creditworthiness of guarantors, insurers, or other forms of credit enhancement on the obligation and takes into account the currency in which the obligation is denominated. The opinion reflects S&P Global Ratings’ view of the obligor’s capacity and willingness to meet its financial commitments as they come due, and this opinion may assess terms, such as collateral security and subordination, which could affect ultimate payment in the event of default.

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Ratings assigned on Moody’s global long-term and short-term rating scales are forward-looking opinions of the relative credit risks of financial obligations issued by non-financial corporates, financial institutions, structured finance vehicles, project finance vehicles, and public sector entities.

Fitch’s credit ratings relating to issuers are an opinion on the relative ability of an entity to meet financial commitments, such as interest, preferred dividends, repayment of principal, insurance claims or counterparty obligations. Fitch credit ratings are used by investors as indications of the likelihood of receiving the money owed to them in accordance with the terms on which they invested. Fitch’s credit ratings cover the global spectrum of corporate, sovereign financial, bank, insurance, and public finance entities (including supranational and sub-national entities) and the securities or other obligations they issue, as well as structured finance securities backed by receivables or other financial assets.

DBRS Morningstar provides independent credit ratings services for financial institutions, corporate and sovereign entities as well as in respect of structured finance products and instruments. Credit ratings are forward-looking opinions about credit risk that reflect the creditworthiness of an issuer, rated entity, security and/or obligation based on DBRS Morningstar’s quantitative and qualitative analysis in accordance with applicable methodologies and criteria. The Rating Committee process facilitates rating decisions, which are a collective assessment of DBRS Morningstar’s opinion rather than the view of an individual analyst. Ratings are based on sufficient information that incorporates both global and local considerations and the use of approved methodologies. They are independent of any actual or perceived conflicts of interest. DBRS Morningstar credit ratings are formed and disseminated based on established methodologies, models and criteria (Methodologies) that apply to entities and securities that we rate, including corporate finance issuers, financial institutions, insurance companies, public finance and sovereign entities as well as Structured Finance transactions. DBRS Morningstar methodologies are periodically reviewed and updated by the team.

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