# EDGAR Filing Document

**Accession Number:** 0000710124
**File Stem:** 0001193125-26-085237
**Filing Date:** 2026-3
**Character Count:** 120360
**Document Hash:** aa6eacbb44fa6ddf392052ee9942165b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-085237.hdr.sgml**: 20260302

**ACCESSION NUMBER**: 0001193125-26-085237

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 21

**FILED AS OF DATE**: 20260302

**DATE AS OF CHANGE**: 20260302

**EFFECTIVENESS DATE**: 20260302

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** NORTHERN INSTITUTIONAL FUNDS
- **CENTRAL INDEX KEY:** 0000710124

**ORGANIZATION NAME:**
- **EIN:** 363209613
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1130

**FILING VALUES:**
- **FORM TYPE:** 497
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 002-80543
- **FILM NUMBER:** 26707111

**BUSINESS ADDRESS:**
- **STREET 1:** NORTHERN INSTITUTIONAL FUNDS
- **STREET 2:** 50 SOUTH LASALLE STREET
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60603
- **BUSINESS PHONE:** 800-637-1380

**MAIL ADDRESS:**
- **STREET 1:** NORTHERN INSTITUTIONAL FUNDS
- **STREET 2:** 50 SOUTH LASALLE STREET
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60603

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** BENCHMARK FUNDS
- **DATE OF NAME CHANGE:** 19920703

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** BENCHMARK MONEY MARKET FUND DIVERSIFIED ASSETS & GOVERNMENT
- **DATE OF NAME CHANGE:** 19910422

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** BENCHMARK MONEY MARKET FUND
- **DATE OF NAME CHANGE:** 19851020

## Series and Classes Contracts Data

### Treasury Instruments Portfolio (Series ID: S000058876)

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|  |  |  |
|:---|:---|:---|
| Class Name             | Ticker Symbol | Class ID   |
| DIGITAL ENABLED SHARES | NDEXX         | C000271532 |

---

## Series and Classes Contracts Data

### Treasury Instruments Portfolio (Series ID: S000058876)

| Class ID   | Class Name             | Ticker Symbol   |
|:---|:---|:---|
| C000271532 | DIGITAL ENABLED SHARES | NDEXX           |

?xml version='1.0' encoding='ASCII'? 497

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#### MONEY MARKET PORTFOLIOS

#### NORTHERN INSTITUTIONAL FUNDS

#### TREASURY INSTRUMENTS PORTFOLIO
DIGITAL ENABLED SHARES (NDEXX)

#### Prospectus dated February 6, 2026, as amended March 2, 2026
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 bank account and is not insured or guaranteed by the Federal Deposit Insurance Corporation ("FDIC"), any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank. The Portfolio's sponsor is not required to reimburse the Portfolio for losses, and you should not expect that the sponsor will provide financial support to the Portfolio at any time, including during periods of market stress.

The Securities and Exchange Commission ("SEC") has not approved or disapproved these securities or passed upon the adequacy of this Prospectus. Any representation to the contrary is a criminal offense.

---

| | |
|:---|:---|
| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS<sub>1</sub> | MONEY MARKET PORTFOLIOS |

---

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#### MONEY MARKET PORTFOLIOS

#### **TABLE OF CONTENTS**

---

| | | |
|:---|:---|:---|
| 3 | **[PORTFOLIO SUMMARY](#tx112881_1)** | **[PORTFOLIO SUMMARY](#tx112881_1)** |
| 7 | **[INVESTMENT ADVISER](#tx112881_2)** | **[INVESTMENT ADVISER](#tx112881_2)** |
| 8 | **[MANAGEMENT FEES](#tx112881_3)** | **[MANAGEMENT FEES](#tx112881_3)** |
| 9 | **[OTHER PORTFOLIO SERVICES](#tx112881_4)** | **[OTHER PORTFOLIO SERVICES](#tx112881_4)** |
| 10 | **[PURCHASING AND SELLING DIGITAL ENABLED SHARES](#tx112881_5)** | **[PURCHASING AND SELLING DIGITAL ENABLED SHARES](#tx112881_5)** |
|  | **10** | [SHARE CLASSES](#tx112881_7) |
|  | **10** | [PURCHASING DIGITAL ENABLED SHARES](#tx112881_8) |
|  | **10** | [OPENING AN ACCOUNT](#tx112881_9) |
|  | **11** | [SELLING DIGITAL ENABLED SHARES](#tx112881_10) |
| 12 | **[ACCOUNT POLICIES AND OTHER INFORMATION](#tx112881_11)** | **[ACCOUNT POLICIES AND OTHER INFORMATION](#tx112881_11)** |
| 18 | **[DISTRIBUTIONS AND TAX CONSIDERATIONS](#tx112881_12)** | **[DISTRIBUTIONS AND TAX CONSIDERATIONS](#tx112881_12)** |
| 20 | **[SECURITIES, TECHNIQUES AND RISKS](#tx112881_13)** | **[SECURITIES, TECHNIQUES AND RISKS](#tx112881_13)** |
|  | **20** | [ADDITIONAL INFORMATION ON INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND RELATED RISKS, DESCRIPTION OF SECURITIES AND COMMON INVESTMENT TECHNIQUES](#tx112881_14) |
| 26 | **[FINANCIAL HIGHLIGHTS](#tx112881_15)** | **[FINANCIAL HIGHLIGHTS](#tx112881_15)** |
| 32 | **[FOR MORE INFORMATION](#tx112881_16)** | **[FOR MORE INFORMATION](#tx112881_16)** |

---

---

| | |
|:---|:---|
| MONEY MARKET PORTFOLIOS<sub>2</sub> | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

---

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#### MONEY MARKET PORTFOLIOS

#### PORTFOLIO SUMMARY

#### TREASURY INSTRUMENTS PORTFOLIO—DIGITAL ENABLED SHARES

#### 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 conditions, exclusively in U.S. Treasury securities.

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

---

| | |
|:---|:---|
| **Shareholder Fees** (fees paid directly from your investment) | **Shareholder Fees** (fees paid directly from your investment) |
| **Annual Portfolio Operating Expenses** (expenses that you pay each<br> year as a percentage of the value of your investment) | **Annual Portfolio Operating Expenses** (expenses that you pay each<br> year as a percentage of the value of your investment) |
|  | **Digital<br> Enabled Shares** |
|  Management Fees | 0.16% |
|  Other Expenses<sup>(1)</sup> | 0.02% |
| &nbsp;&nbsp;&nbsp;&nbsp; Transfer Agent Fees | 0.02% |
| &nbsp;&nbsp;&nbsp;&nbsp; Service Fees |  |
| &nbsp;&nbsp;&nbsp;&nbsp; Other Operating Expenses |  |
|  **Total Annual Portfolio Operating Expenses** | 0.18% |
|  Expense Reimbursement<sup>(2)</sup> | 0.00% |
|  **Total Annual Portfolio Operating Expenses After Expense Reimbursement** | 0.18% |

---

*<sup>(1)</sup>* *"Other Expenses" are based on estimated amounts for the current fiscal year.*

*<sup>(2)</sup>* *Northern Trust Investments, Inc. ("NTI") has contractually agreed to reimburse a portion of the operating expenses of the Portfolio so that after such reimbursement the Total Annual Fund Operating Expenses of the Portfolio (excluding (i) acquired fund fees and expenses; (ii) service fees; (iii) the compensation paid to each Independent Trustee of the Trust; (iv) expenses of third party consultants engaged by the Board of Trustees; (v) membership dues paid to the Investment Company Institute and Mutual Fund Directors Forum; (vi) expenses in connection with the negotiation and renewal of the revolving credit facility; and (vii) extraordinary expenses and interest) do not exceed 0.18%. This contractual limitation may not be terminated before April 1, 2027 without the approval of the Board of Trustees.* 

#### EXAMPLE
The following Example is intended to help you compare the cost of investing in Digital Enabled 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. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

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| | | | | |
|:---|:---|:---|:---|:---|
|  | **1 Year** | **3 Years** | **5 Years** | **10 Years** |
|  **Digital Enabled Shares** | $18 | $58 | $101 | $230 |

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#### PRINCIPAL INVESTMENT STRATEGIES
The Portfolio seeks to achieve its objective by investing, under normal circumstances, its total assets exclusively in:

∎ Cash; and

∎ Short-term bills, notes and other obligations issued or guaranteed by the U.S. Treasury ("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. Repurchase agreements are agreements in which the Portfolio agrees to purchase portfolio securities from financial institutions subject to the seller's agreement to repurchase them at a mutually agreed upon date and price.

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

The Securities and Exchange Commission ("SEC") imposes strict requirements on the investment quality, maturity, diversification and liquidity of the Portfolio's investments. Accordingly, the Portfolio invests in U.S. dollar-denominated securities with a remaining maturity of no more than 397 days (with certain exceptions permitted by applicable regulations). The Portfolio maintains a dollar-weighted average portfolio maturity of no more than 60 calendar days, and a dollar-weighted average portfolio maturity as determined without exceptions regarding certain interest rate adjustments under Rule 2a-7 of no more than 120 calendar days. The Portfolio will limit its investments to "eligible securities," as defined by

---

| | |
|:---|:---|
| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS<sub>3</sub> | MONEY MARKET PORTFOLIOS |

---

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#### MONEY MARKET PORTFOLIOS

#### TREASURY INSTRUMENTS PORTFOLIO—DIGITAL ENABLED SHARES
applicable regulations, at the time of acquisition (e.g., government securities, shares of other money market funds, and securities that present minimal credit risks as determined by NTI, pursuant to guidelines approved by the Portfolio's Board of Trustees). The Portfolio may invest in variable and floating rate instruments. The Portfolio's investment adviser may consider, among other things, credit and interest rate risks as well as general market conditions when deciding whether to buy or sell investments for the Portfolio. The Portfolio will generally hold a portion of its assets in cash to accommodate anticipated redemptions.

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

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

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

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

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

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

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

LARGE SHAREHOLDER RISK is the risk that a large proportion of the interests of the Portfolio may be held by a small number of investors (or a single investor) and 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

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| | |
|:---|:---|
| MONEY MARKET PORTFOLIOS<sub>4</sub> | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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#### MONEY MARKET PORTFOLIOS

#### TREASURY INSTRUMENTS PORTFOLIO—DIGITAL ENABLED SHARES
smaller asset base. Large purchases of the Portfolio's shares or having a more concentrated shareholder base 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.

INVESTMENT COMPANY RISK is the risk that the Portfolio will be subject to the risks associated with investments in registered investment companies ("Underlying Funds"), such as the possibility that the value of the securities or instruments held by the Underlying Funds could decrease. Investments in Underlying Funds may involve duplication of management fees and certain other expenses, as the Portfolio indirectly bears its proportionate share of any expenses paid by the Underlying Funds in which it invests. NTI may be subject to potential conflicts of interest with respect to investments in affiliated Underlying Funds, which are Underlying Funds managed by NTI or its affiliates, because the fees paid to NTI by some affiliated Underlying Funds may be higher than the fees paid by other Underlying Funds.

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

CASH POSITIONS RISK is the risk that maintaining cash positions may negatively affect the Portfolio's performance and potentially limit investment opportunities as a result of the Portfolio's uninvested assets. Maintaining cash positions may also subject the Portfolio to increased credit risk exposure to the custodian bank.

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

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

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

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

#### PORTFOLIO PERFORMANCE
The bar chart and table that follow provide an indication of the risks of investing in the Portfolio by showing changes in the performance of the Portfolio from year to year. As of the date of this Prospectus, Digital Enabled Shares had not commenced operations. Digital Enabled Shares would have similar annual returns when compared with Shares because each class is invested in the same portfolio of securities. The annual return of Shares would differ from those of Digital Enabled Shares 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 www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-institutional or by calling 800-637-1380.

#### CALENDAR YEAR TOTAL RETURNS (SHARES)\*
*\* For the periods shown in the bar chart above:* 

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| | |
|:---|:---|
| &nbsp;&nbsp; highest quarterly return | 1.07% |
| &nbsp;&nbsp; lowest quarterly return | 0.99% 4<sup>th</sup> quarter of 2025 |

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| | |
|:---|:---|
| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS<sub>5</sub> | MONEY MARKET PORTFOLIOS |

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#### MONEY MARKET PORTFOLIOS

#### TREASURY INSTRUMENTS PORTFOLIO—DIGITAL ENABLED SHARES
**AVERAGE ANNUAL TOTAL RETURNS** 

*(For the periods ended December 31, 2025)*

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| | | | |
|:---|:---|:---|:---|
|  | Inception<br> Date | 1 Year | Since<br> Inception |
| &nbsp;&nbsp; Shares | 10/07/2024 | 4.26% | 4.35% |

---

*The 7-day yield for Shares of the Portfolio as of December 31, 2025: 3.75%. For the current 7-day yield call 800-637-1380 or visit www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-institutional.* 

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

#### PURCHASE AND SALE OF PORTFOLIO SHARES
You may purchase Digital Enabled Shares of the Portfolio through certain authorized intermediaries. An "authorized intermediary" is a financial intermediary that has entered into an intermediary agreement with NTI for the sale of Digital Enabled Shares of the Portfolio. Although the Portfolio does not currently employ blockchain technology or invest in crypto assets, Digital Enabled Shares are expected to be purchased and held through intermediaries that intend to use blockchain technology to maintain a mirror record of share ownership for their customers.

There is no minimum investment imposed upon intermediaries for the purchase of Digital Enabled Shares. When you purchase, sell (redeem) or exchange Digital Enabled Shares through an authorized intermediary, you may be required to pay a commission and/or other forms of compensation to the intermediary. In addition, an authorized intermediary may impose different investment minimums than those set forth above. The Portfolio is not responsible for any investment minimums imposed by authorized intermediaries or for notifying shareholders of any changes to them.

On any business day, you may sell (redeem) or exchange Digital Enabled Shares of the Portfolio by contacting your authorized intermediary.

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

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

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| | |
|:---|:---|
| MONEY MARKET PORTFOLIOS<sub>6</sub> | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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#### MONEY MARKET PORTFOLIOS

#### 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 their 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 December 31, 2025 Northern Trust Corporation, through its affiliates, had assets under investment management of approximately $1.8 trillion and assets under custody of approximately $14.9 trillion.

Under the Management Agreement 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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|:---|:---|
| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS<sub>7</sub> | MONEY MARKET PORTFOLIOS |

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#### MONEY MARKET PORTFOLIOS

#### 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. The table below reflects the aggregate management fees paid by the Portfolio for the fiscal year ended November 30, 2025, after waivers and/or reimbursements, if any (expressed as a percentage of the Portfolio's respective 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's 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 April 1, 2027. 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 with respect to the Portfolio if it determines that it is in the best interest of the Portfolio and its shareholders.

Service providers to the Portfolio, including the Portfolio's adviser and/or its affiliates may, from time to time, voluntarily waive all or a portion of any fees to which they are entitled and/or reimburse certain expenses, 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 without notice. There is no guarantee that the Portfolio will be able to avoid a negative yield or maintain a specified minimum yield.

A discussion regarding the Board of Trustees' basis for its most recent approval of the Portfolio's Management Agreements is available in the Portfolio's filing on Form N-CSR for the six-month period ended May 31, 2025.

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| | |
|:---|:---|
|  | **Aggregate Management Fees Paid<br>for Fiscal Year Ended 11/30/2025<br>after waivers and/or reimbursements, if any** |
| &nbsp;&nbsp; TREASURY INSTRUMENTS PORTFOLIO | 0.03% |

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|:---|:---|
| MONEY MARKET PORTFOLIOS<sub>8</sub> | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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#### MONEY MARKET PORTFOLIOS

#### 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"), a wholly-owned subsidiary of Foreside Financial Group, LLC (dba ACA Group), 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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| | |
|:---|:---|
| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS<sub>9</sub> | MONEY MARKET PORTFOLIOS |

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#### MONEY MARKET PORTFOLIOS

#### PURCHASING AND SELLING DIGITAL ENABLED SHARES

#### THE TRUST OFFERS ONE MONEY MARKET PORTFOLIO TO INSTITUTIONAL INVESTORS IN THIS PROSPECTUS.
The description 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 not be relied upon as a complete investment program.

#### SHARE CLASSES
The Portfolio is authorized to offer five classes of shares (Shares, Service Shares, Premier Shares, Siebert Williams Shank Shares and Digital Enabled Shares). Shares, Service Shares, Premier Shares and Siebert Williams Shank Shares are described in separate prospectuses. Digital Enabled Shares of each class bear their pro rata portion of all operating expenses paid by the Portfolio, except for service fee amounts payable under an applicable Service Plan and transfer agent fees.

Please note that the fee and expense information shown under "Fees and Expenses of the Portfolio" in the Portfolio Summary does not reflect any charges that may be imposed by TNTC, its affiliates, financial intermediaries and other institutions on their customers or other beneficial owners. (For more information, please see "Account Policies and Other Information—Financial Intermediaries.")

#### PURCHASING DIGITAL ENABLED SHARES
You may purchase Digital Enabled Shares of the Portfolio through certain authorized intermediaries. An "authorized intermediary" is a financial intermediary that has entered into an intermediary agreement with NTI for the sale of Digital Enabled Shares of the Portfolio. Although the Portfolio does not currently employ blockchain technology or invest in crypto assets, Digital Enabled Shares are expected to be purchased and held through intermediaries that intend to use blockchain technology to maintain a mirror record of share ownership for their customers. The authorized financial intermediary, and not the Portfolio, NTI, TNTC or their affiliates, will be responsible ownership records on the blockchain.

There is no minimum investment imposed upon intermediaries for the purchase of Digital Enabled Shares. You should contact an authorized intermediary for information on how to purchase Digital Enabled Shares, including information on account requirements, services, charges, and the authorized intermediary's use of blockchain technology.

The Digital Enabled Shares class of the Portfolio is not offered for purchase through Northern Trust custody sweep.

#### OPENING AN ACCOUNT
THROUGH AN AUTHORIZED INTERMEDIARY. The Trust may authorize certain financial intermediaries (including banks, trust companies, brokers and investment advisers) to accept purchase orders from their customers or other beneficial owners on behalf of the Portfolio. See "Account Policies and Other Information—Financial Intermediaries" for additional information regarding purchases of Digital Enabled Shares through authorized intermediaries. If you purchase shares through an authorized intermediary, that intermediary may impose different investment minimums than those set forth by the Portfolio as described in this Prospectus. The Portfolio is not responsible for any investment minimums imposed by authorized intermediaries or for notifying shareholders of any changes to them.

Customers of an intermediary will normally give their order instructions to the intermediary, and the intermediary will, in turn, place the order with the Transfer Agent. To place an order for Fund shares, intermediaries should either:

#### BY MAIL
∎ Mail a check and acceptable evidence of authority (if applicable) to:

Northern Institutional Funds

P.O. Box 75986

Chicago, Illinois 60675-5986

∎ Additional documentation may be required to fulfill the requirements of the "Customer Identification Program."

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.

∎ For overnight delivery, use the following address:

Northern Institutional Funds

c/o The Northern Trust Company 333 South Wabash Ave Chicago, Illinois 60604

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| MONEY MARKET PORTFOLIOS<sub>10</sub> | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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#### MONEY MARKET PORTFOLIOS

#### BY TELEPHONE
∎ Call the Northern Institutional Funds Center at 800-637-1380.

#### BY WIRE OR AUTOMATED CLEARING HOUSE ("ACH") TRANSFER
∎ Wire federal funds or effect an ACH transfer to:

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 DIGITAL ENABLED SHARES
THROUGH AN AUTHORIZED INTERMEDIARY. You may sell (redeem) your Digital Enabled Shares by contacting your financial intermediary. See "Account Policies and Other Information—Financial Intermediaries" for additional information regarding sales (redemptions) of Digital Enabled Shares through authorized intermediaries. Customers of an intermediary will normally give their order instructions to the intermediary, and the intermediary will, in turn, place the order with the Transfer Agent. To place an order to sell (redeem) Fund shares, intermediaries should either:

#### BY MAIL

#### SEND A WRITTEN REQUEST TO:
Northern Institutional Funds

P.O. Box 75986

Chicago, Illinois 60675-5986

For overnight delivery, use the following address:

Northern Institutional Funds

c/o The Northern Trust Company

333 South Wabash Ave

Chicago, Illinois 60604

#### THE LETTER OF INSTRUCTION MUST INCLUDE:
∎ The signature of a duly authorized person (A signature guarantee from an institution participating in the Stock Transfer Agency Medallion Program ("STAMP") also may be required.)

∎ Your account number

∎ The name of the Portfolio

∎ The number of Digital Enabled Shares and the dollar amount to be redeemed

#### BY TELEPHONE
∎ Call the Northern Institutional Funds Center at 800-637-1380 for instructions.

∎ During periods of unusual economic or market activity, telephone redemptions may be difficult to implement. In such event, shareholders should follow the procedures outlined above under "Selling Digital Enabled Shares—By Mail."

#### 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.

∎ Call the Northern Institutional Funds Center at 800-637-1380 for instructions.

∎ The minimum amount that may be redeemed by this method is $10,000.

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| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS<sub>11</sub> | MONEY MARKET PORTFOLIOS |

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#### MONEY MARKET PORTFOLIOS

#### ACCOUNT POLICIES AND OTHER INFORMATION
PURCHASE AND REDEMPTION MINIMUMS. There is no minimum investment imposed upon intermediaries for the purchase of Digital Enabled Shares. The Trust reserves the right to waive the minimum investment requirement. A $10,000 minimum applies for redemptions by wire. The Trust reserves the right to waive purchase and redemption minimums and to determine the manner in which a minimum is satisfied.

CALCULATING SHARE PRICE. The Trust issues and redeems Digital Enabled Shares at NAV. The NAV for Digital Enabled 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. For each class of shares of the Portfolio, the NAV is calculated on each Business Day as of 1:30 p.m. Central time. 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. See "Good Order."

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 1:30 p.m. Central time with respect to the Portfolio will be executed the day they are received by either the Transfer Agent or other authorized intermediary, at the NAV next calculated after receipt of your purchase order in good order, provided that one of the following occurs:

∎ The Transfer Agent receives the payment in federal or other immediately available funds on the same Business Day by 1:30 p.m. Central time with respect to the Portfolio;

∎ The requests are placed by a financial or authorized intermediary that has entered into a Servicing Agreement or other agreement with the Trust or its agent and payment in federal or other immediately available funds is received by the Transfer Agent in accordance with the terms of the Trust's or its agent's agreement with the intermediary;

∎ Payment in federal or other immediately available funds is received by the close of the same Business Day in an institutional account maintained with Northern Trust or an affiliate; or

∎ The purchase requests are placed through TNTC's electronic fund trading platform and payment in federal or other immediately available funds is received by the Transfer Agent by the close of the Federal Reserve wire transfer system (normally, 5:00 p.m. Central time).

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 applicable Portfolio(s), provided that payment is made as noted above.

IN-KIND PURCHASES AND REDEMPTIONS. The Trust reserves the right to accept payment for Digital Enabled 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 Statement of Additional Information ("SAI") for further information about the terms of these purchases and redemptions.

#### MISCELLANEOUS PURCHASE INFORMATION.
∎ Financial intermediaries are responsible for transmitting purchase orders and delivering required funds on a timely basis. Your financial intermediary may have earlier trading deadlines than those described in this prospectus. Please contact your financial intermediary for more information.

∎ Investors are responsible for all losses and expenses of the Portfolio, and purchase orders may be cancelled, in the event of any failure to make payment according to the procedures outlined in this Prospectus. In addition, a $20 charge will be imposed if a check does not clear.

∎ Exchanges into the Portfolio from another investment portfolio in the Trust may be subject to any redemption fee imposed by the other investment portfolio.

∎ Digital Enabled Shares of the Portfolio are entitled to the dividends declared by the Portfolio beginning on the Business Day the purchase order is executed, provided payment in federal or other immediately available funds is received by the Transfer Agent by the time designated in "Timing of Purchase Requests."

∎ The Trust and its agents, each reserve the right, in the Trust's sole discretion to reject or restrict any purchase order or exchange order, in whole or in part. The Trust also reserves the right to change or discontinue any of its purchase procedures.

∎ The Trust and its agents, each reserve the right to suspend the offering of shares of the Portfolio when, in the judgment of management, such suspension is in the best interests of the Portfolio.

∎ In certain circumstances, the Trust may advance the time by which purchase orders must be received. See "Early Closings."

∎ If the Transfer Agent cannot locate an investor for a period of time specified by appropriate state law, the investor's account may be deemed legally abandoned and then escheated (transferred) to such state's unclaimed property administrator

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| MONEY MARKET PORTFOLIOS<sub>12</sub> | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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#### MONEY MARKET PORTFOLIOS
in accordance with statutory requirements. The state may sell escheated shares of the Portfolio and, if an investor subsequently seeks to reclaim the proceeds of liquidation from the state, the investor may only be able to recover the amount received when the shares of the Portfolio were sold. To avoid these outcomes and protect their property, shareholders that invest in the Portfolio through an account held directly with the Portfolio's transfer agent are encouraged to routinely confirm that the mailing address on their account is current and valid and contact the transfer agent at least once a year by mail, by phone (800-637-1380), or by logging into their account. The Portfolio, its Board of Trustees, and the Transfer Agent will not be liable to investors or their representatives for good faith compliance with state unclaimed property laws. Investors are responsible for checking their state's unclaimed or abandoned property website for specific information. <br>

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 1:30 p.m. Central time with respect to the Portfolio will be executed on the same day at the NAV next calculated after receipt of your redemption order in good order.

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 the 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 Digital Enabled 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 from banks, including through the Trust's committed, unsecured credit facility (see "Credit Facility and Borrowing"). 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. However, the Board of Trustees reserves the right, with notice to shareholders, to change this policy with respect to the Portfolio, thereby permitting the Portfolio to impose discretionary liquidity fees 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:

∎ The Trust reserves the right to defer crediting, sending or wiring redemption proceeds for up to 7 days (or such longer period permitted by the SEC) after receiving the redemption order if, in its judgment, an earlier payment could adversely affect the Portfolio. The processing of redemptions may be suspended, and the delivery of redemption proceeds may be delayed beyond seven days, depending on the circumstances, for any period: (i) during which the New York Stock

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| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS<sub>13</sub> | MONEY MARKET PORTFOLIOS |

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Exchange (the "Exchange") is closed (other than on holidays or weekends), or during which trading on the Exchange is restricted; (ii) when, in accordance with SEC rules and regulations, an emergency exists that makes the disposal of securities owned by the Portfolio or the determination of the fair value of the Portfolio's net assets not reasonably practicable; (iii) as permitted by order of the SEC for the protection of Portfolio shareholders; or (iv) the Portfolio as part of a liquidation of the Portfolio, has suspended redemption of shares in accordance with SEC rules and regulations. Redemption payments may also be delayed in the event of a non-routine closure of the Federal Reserve wire payment system or applicable Federal Reserve Banks. <br>

∎ If you are redeeming recently purchased Digital Enabled Shares by check or electronic transaction, your redemption request may not be paid until your check or electronic transaction has cleared. This may delay your payment for up to 10 days.

∎ Financial intermediaries are responsible for transmitting redemption orders and crediting your account with redemption proceeds on a timely basis. Your financial intermediary may have earlier trading deadlines than those described in this prospectus. Please contact your financial intermediary for more information.

∎ Redemption requests made to the Transfer Agent by mail must be signed by a person authorized by acceptable documentation on file with the Transfer Agent.

∎ Dividends on Digital Enabled Shares are earned through and including the day prior to the day on which they are redeemed.

∎ Subject to applicable law, the Trust and the Transfer Agent reserve the right to redeem shares held by any shareholder who provides incorrect or incomplete account information or when such involuntary redemptions are necessary to avoid adverse consequences to the Trust and its shareholders or the Transfer Agent.

∎ Subject to applicable law, the Trust, Northern Trust and their agents reserve the right to involuntarily redeem or suspend an account at the Portfolio's then current NAV, in cases of disruptive conduct, suspected fraudulent or illegal activity, inability to verify the identity of an investor, or other circumstances determined by the Trust and Northern Trust to be in the best interest of the Trust and its shareholders.

∎ The Trust, Northern Trust and their agents reserve the right, without notice, to freeze any account and/or suspend account services when: (i) notice has been received of a dispute regarding the assets in an account, or a legal claim against an account; (ii) upon initial notification to Northern Trust of a shareholder's or authorized agent's death until Northern Trust receives required documentation in correct form; or (iii) if there is reason to believe a fraudulent transaction may occur or has occurred.

∎ The Trust may require any information from the shareholder reasonably necessary to ensure that a redemption request has been duly authorized.

∎ The Trust reserves the right to change or discontinue any of its redemption procedures.

∎ The Trust does not permit redemption proceeds to be sent by outgoing International ACH Transaction ("IAT"). An IAT is a payment transaction involving a financial institution's office located outside U.S. territorial jurisdiction.

∎ In certain circumstances, the Trust may advance the time by which redemption and exchange orders must be received. See "Early Closings."

EXCHANGE PRIVILEGES. Financial intermediaries and their customers (to the extent permitted by their account agreements) may exchange shares of the Portfolio for the same class of shares of another investment portfolio of the Trust only 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. At this time, Digital Enabled Shares are not offered by another investment portfolio of the Trust.

An exchange is a redemption of shares of the Portfolio and the purchase of the same class 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.

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| MONEY MARKET PORTFOLIOS<sub>14</sub> | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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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.

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 a financial intermediary or other investor 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 below $5 million, the Trust requests that a financial intermediary or other investor 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 day that the Exchange is open for business, except when the following federal holidays are observed: Columbus Day and Veterans Day. Portfolio shares will generally not be priced on days that the Exchange is closed, although Portfolio shares may be priced on such days if the Securities Industry and Financial Markets Association ("SIFMA") recommends that the bond markets remain open for all or part of the day.

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 the Portfolio for purchase, redemption and exchange transactions if the

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| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS | **15** | MONEY MARKET PORTFOLIOS |

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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 www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-institutional.

FINANCIAL INTERMEDIARIES. The Trust may authorize certain financial intermediaries (including banks, trust companies, brokers and investment advisers) to accept purchase, redemption and exchange orders from their customers or other beneficial owners 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. Orders submitted through a financial intermediary that has not received authorization to accept orders on the Portfolio's behalf are priced at the Portfolio's NAV next calculated by the Portfolio after it receives the order from the financial intermediary and accepts it, which may not occur on the day submitted to the financial intermediary.

In addition, Northern Trust may enter into agreements with financial intermediaries through which customers or other beneficial owners own shares of the Digital Enabled Shares class of the Portfolio, pursuant to which Northern Trust pays these financial intermediaries for providing certain shareholder 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 Digital Enabled 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 or other beneficial owner has agreed with a particular financial intermediary to maintain a minimum balance and the balance falls below this minimum, the customer or other beneficial owner 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 Digital Enabled 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 or other beneficial owners 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 www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-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 or subsequent calendar day of the preceding 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-MFP. Form N-MFP will be made available to the public on the SEC's EDGAR database

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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-MFP 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 and an annual shareholder report as of May 31 and November 30, respectively. The reports will be made available on the Portfolio's website at www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-institutional/literature. Paper copies of these reports will be mailed to each shareholder of record that has not elected to receive the reports electronically. You may elect to receive future reports electronically at any time by contacting your financial intermediary or, if you invest directly with the Trust, by calling the Northern Institutional Funds Center at 800-637-1380 or by sending an e-mail request to northernfunds@ntrs.com. Your election to receive reports electronically 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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| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS | **17** | MONEY MARKET PORTFOLIOS |

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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 Digital Enabled 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.

#### 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 has elected and 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 Digital Enabled 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.

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. For the 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.

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 effectively connected to a trade or business of the recipient in the United States or if the recipient is present in the United

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| MONEY MARKET PORTFOLIOS | **18** | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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#### MONEY MARKET PORTFOLIOS
States for 183 days or more in a taxable year and certain other conditions are met.

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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| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS | **19** | MONEY MARKET PORTFOLIOS |

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#### SECURITIES, TECHNIQUES AND RISKS

#### ADDITIONAL INFORMATION ON INVESTMENT OBJECTIVE, 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 apply to the Portfolio, unless otherwise noted. 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. Future legislative, regulatory, or tax developments may affect the investments or investment strategies available to NTI in connection with managing the Portfolio, which may also adversely affect the Portfolio's return potential and ability of the Portfolio to achieve its investment objective.

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 each of the Portfolio is not a bank account and is not insured or guaranteed by the FDIC, any other government agency 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.

The securities purchased by the Portfolio are subject to the maturity, quality, liquidity, diversification, and other requirements of Rule 2a-7. Consistent with Rule 2a-7, the Portfolio:

∎ Limits its dollar-weighted average portfolio maturity to 60 days or less;

∎ Limits its dollar-weighted average portfolio maturity without regard to maturity shortening provisions regarding interest rate readjustments under Rule 2a-7 (also known as dollar-weighted average portfolio life) to 120 days or less;

∎ Buys securities with remaining maturities of 397 days or less or securities otherwise permitted to be purchased because of maturity shortening provisions under Rule 2a-7; and

∎ Invests only in U.S. dollar-denominated securities.

In addition, the Portfolio limits its investments to "Eligible Securities," as defined by the SEC, at the time of acquisition. 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.

An "Eligible Security" means a security (i) that has been determined by NTI, subject to guidelines approved by the Portfolio's Board of Trustees, to present minimal credit risks to the fund; (ii) that is issued by other investment companies that are money market funds; or (iii) that is a U.S. government security.

In making minimal credit risk determinations, NTI includes an analysis of the capacity of each security's issuer or guarantor to meet its financial obligations.

INVESTMENT OBJECTIVES. The investment objective of the Portfolio may be changed by the Trust's Board of Trustees without shareholder approval. Shareholders will, however, be notified of any changes.

During extraordinary market conditions and interest rate environments, all or any portion of the assets of the Portfolio may be uninvested (i.e., a portion of the Portfolio's assets may be held in cash). The Portfolio may not achieve its investment objectives during this time.

CREDIT (OR DEFAULT) RISK 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. 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 in a timely manner may cause the value of a fixed income security to decline. 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 rapid deterioration in the market value of the Portfolio's securities. 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.

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. In addition, changes in the dividend policies of companies held by the Portfolio could

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| MONEY MARKET PORTFOLIOS | **20** | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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#### MONEY MARKET PORTFOLIOS
make it difficult for the Portfolio to provide a predictable level of income. Income risk is generally higher for short-term debt securities.

INTEREST RATE RISK The Portfolio's yield will vary with changes in interest rates. During periods of rising interest rates, the market value of the Portfolio's securities will tend to be lower than prevailing market rates and in periods of falling interest rates, the market value of the Portfolio's securities will tend to be higher. The Portfolio's yield will vary as short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. In a period of rising interest rates, the Portfolio's yield may not increase proportionately or 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.

During periods when inflation rates are high or rising, or during periods of low interest rates, the Portfolio may be subject to a greater risk of rising interest rates. Changing interest rates may have unpredictable effects on the markets and the Portfolio's investments, may result in heightened market volatility, may impact the liquidity of fixed-income securities and of the Portfolio, and may detract from Portfolio performance. A low or negative 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 may impair the Portfolio's ability to maintain a stable NAV per share. 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.

LARGE SHAREHOLDER RISK 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. Such redemptions may force the Investment Adviser to sell portfolio securities or invest cash when the Investment Adviser would not otherwise choose to do so. Redemptions by a large shareholder may also 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 shareholder redemption could result in the Portfolio's current expenses being allocated over a smaller asset base, leading to an increase in the Portfolio's expense ratio. Large shareholder purchases of the Portfolio's shares or having a more concentrated shareholder base 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. There can be no assurance that any large shareholder or large group of shareholders would not redeem their investment or that the size of the Portfolio would be maintained.

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 through interest rate changes. 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. 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 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

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| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS | **21** | MONEY MARKET PORTFOLIOS |

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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.

RECENT MARKET EVENTS. 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.

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. Such policy changes may adversely affect the value, volatility and liquidity of dividend and interest paying securities. 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.

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

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. 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. 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.

U.S. GOVERNMENT SECURITIES 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 (including zero coupon securities).

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.

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| MONEY MARKET PORTFOLIOS | **22** | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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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. 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).

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). U.S. government securities include zero coupon securities, which tend to be subject to greater market risk than interest-paying securities of similar maturities.

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 tied to a specified index rate. These instruments include floating rate Treasury obligations and short- 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 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.

CASH POSITIONS As government money market funds, a portion of the Portfolio's assets will likely be held in cash, primarily to meet redemptions.

SPECIAL RISKS. Maintaining cash positions may negatively affect the Portfolio's performance and potentially limit investment opportunities as a result of the Portfolio's uninvested assets. Maintaining cash positions may also subject the Portfolio to increased credit risk exposure to the custodian bank.

OTHER SECURITIES AND RISKS. 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 can also use the investment techniques and strategies described below. The Portfolio might not use all of these techniques or strategies or might only use them from time to time.

BORROWINGS. The Portfolio may borrow money from banks.

The Portfolio may borrow money from banks in amounts up to 33-1/3% of its total assets (including the amount borrowed).

Borrowing involves leveraging.

CREDIT FACILITY AND BORROWING. The Portfolio, the other portfolios of the Trust, and affiliated funds of Northern Funds for purposes of this discussion, (the "Borrowing Funds") have jointly entered into a revolving credit facility (the "Credit Facility") whereby the Borrowing Funds may borrow for the temporary funding of shareholder redemptions or for other temporary or emergency purposes. Pursuant to the Credit Facility, the participating Borrowing Funds may borrow up to an aggregate commitment amount of $185 million (the "Commitment Limit") at any time, subject to asset coverage and other legal, regulatory or contractual limitations as specified in the Credit Facility and under the 1940 Act. Borrowing results in interest expense and other fees and expenses for the Borrowing Funds that may impact the Portfolio's expenses, including any net expense ratios. The costs of borrowing may reduce a Borrowing Fund's yield. If a Borrowing Fund borrows pursuant to the Credit Facility, it is charged interest at a variable rate. Each Borrowing Fund 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 Borrowing Funds' borrowings under the Credit Facility. As

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such, a Borrowing Fund may be unable to borrow (or borrow further) under the Credit Facility if the Commitment Limit has been reached.

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. Investments in other government money market funds are included in the Portfolio's 99.5% policy.

INVESTMENT STRATEGY. Investments by the Portfolio in other investment companies will be subject to the limitations of the 1940 Act except as permitted by applicable SEC exemptive orders or rules, or no-action relief. 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. Investments in other investment companies are subject to the risks of investing in the underlying securities or other instruments that such investment companies own. The value of the investments of an investment company in which the Portfolio invests will fluctuate in response to various market and economic factors related to the markets, as well as the financial condition and prospects of issuers in which the underlying investment companies invest. There can be no assurance that the underlying investment companies will achieve their investment objectives, and their performance may be lower than their represented asset classes.

The Portfolio will bear a proportionate share of any fees and expenses paid by the investment companies in which the Portfolio invests. Because other investment companies pay advisory, administrative and/or service fees that are borne indirectly by investors, such as the Portfolio, there may be duplication of investment management and other fees.

TEMPORARY INVESTMENTS. For capital preservation and liquidity, the Portfolio may have a greater concentration in short-term securities, 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.

The Portfolio may, from time to time, take temporary defensive positions by holding cash, shortening the Portfolio's dollar-weighted average portfolio maturity or investing in other securities that are Eligible Securities for purchase by money market funds as described in the Portfolio's SAI, in anticipation of or in response to adverse market, economic, political or other conditions. In addition, the Portfolio may invest in repurchase agreements in anticipation of or in response to adverse market, economic, political or other conditions. If the Portfolio's portfolio managers do so, different factors could affect the Portfolio's performance and the Portfolio may not achieve its investment objective.

The following provides additional risk information regarding investing in the Portfolio.

CYBERSECURITY RISK. 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 operations and data may be compromised as a result of internal and external cyber-failures, breaches or attacks ("Cyber Risk"). In general, cyber incidents can result from deliberate attacks or unintentional events. 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.

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 information technology 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 does not directly 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

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| MONEY MARKET PORTFOLIOS | **24** | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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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.

BLOCKCHAIN TECHNOLOGY RISK.The Portfolio does not currently employ blockchain technology or invest in crypto assets. Intermediaries through whom shareholders purchase and redeem Digital Enabled Shares, however, intend to employ blockchain technology to maintain a mirror record of share ownership for its customers. A blockchain is a distributed ledger that facilitates the process of recording transactions and tracking assets in a business network. Assets are represented on the blockchain through tokens, which are digital representations of an asset and are built into the blockchain. Blockchain networks are based upon software source code that establishes and governs their respective cryptographic systems for verifying transactions. Complex information technology and communications systems, such as blockchain networks, are subject to various threats and/or risks (including operational, information security, cyber-attacks and related risks) that could adversely affect the Portfolio, its shareholders and intermediaries through whom you purchase and redeem shares of the Portfolio. The use of blockchain technology is relatively new and the regulatory framework applicable to such use in the United States is still evolving, which might result in regulatory uncertainty or concerns that could require changes to the manner in which such technology is used, impose additional regulatory obligations, and negatively impact investors. Blockchain systems could be vulnerable to fraud. The Portfolio, its investment manager, distributor, transfer agent and their affiliates will not be responsible for any loss in connection with the use of blockchain technology by authorized intermediaries. You should contact your intermediary about whether or how it uses blockchain technology and the associated risks.

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.

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.

The Portfolio may invest in other securities and are 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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| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS | **25** | MONEY MARKET PORTFOLIOS |

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#### FINANCIAL HIGHLIGHTS
**THE FINANCIAL HIGHLIGHTS TABLE IS INTENDED TO HELP YOU UNDERSTAND THE PORTFOLIO'S FINANCIAL PERFORMANCE FOR THE PAST FIVE YEARS. BECAUSE THE DIGITAL ENABLED SHARES ARE A NEW CLASS OF SHARES OF THE PORTFOLIO, INFORMATION IS SHOWN FOR THE PORTFOLIO'S SHARES CLASS AND PREMIER CLASS SHARES, WHICH ARE OFFERED IN A SEPARATE PROSPECTUS.** 

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

The information for the fiscal periods ended November 30 have 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 filing on Form N-CSR. Copies of the semiannual and annual report are available upon request and without charge. The Portfolio's Form N-CSR filed with the SEC, which is available upon request and without charge by calling 800-637-1380, is also available on the Trust's website at www.northerntrust.com/united-states/what-we-do/investment-management/northern-funds/funds-and-performance-institutional.

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| MONEY MARKET PORTFOLIOS | **26** | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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#### MONEY MARKET PORTFOLIOS

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|:---|:---|
| **FINANCIAL HIGHLIGHTS**  | FOR THE PERIOD ENDED NOVEMBER 30,  |

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| | | |
|:---|:---|:---|
| **TREASURY INSTRUMENTS PORTFOLIO** | **SHARES** | **SHARES** |
| **Selected per share data** | **2025** | **2024<sup>(1)</sup>** |
| **Net Asset Value, Beginning of Period** | $1.00 | $1.00 |
| INCOME FROM INVESTMENT OPERATIONS: |  |  |
| Net investment income | 0.04 | 0.01 |
| Net realized gains (losses)<sup>(2)</sup> |  |  |
| &nbsp;&nbsp;&nbsp;&nbsp; Total from Investment Operations | 0.04 | 0.01 |
| LESS DISTRIBUTIONS PAID: |  |  |
| From net investment income | (0.04) | (0.01) |
| &nbsp;&nbsp;&nbsp;&nbsp; Total Distributions Paid | (0.04) | (0.01) |
| Net Asset Value, End of Period | $1.00 | $1.00 |
| **Total Return<sup>(3)</sup>** | 4.32%<sup>(4)</sup> | 0.70%<sup>(5)</sup> |
| SUPPLEMENTAL DATA AND RATIOS: |  |  |
| Net assets, in thousands, end of period | $2642260 | $423060 |
| Ratio of average net assets of: |  |  |
| &nbsp;&nbsp;&nbsp;&nbsp; Expenses, net of waivers, reimbursements and credits | 0.05% | 0.04%<sup>(6)</sup> |
| &nbsp;&nbsp;&nbsp;&nbsp; Expenses, before waivers, reimbursements and credits | 0.18% | 0.19%<sup>(6)</sup> |
| &nbsp;&nbsp;&nbsp;&nbsp; Net investment income, net of waivers, reimbursements and credits | 4.17% | 4.66%<sup>(6),(7)</sup> |
| &nbsp;&nbsp;&nbsp;&nbsp; Net investment income, before waivers, reimbursements and credits | 4.04% | 4.51%<sup>(6),(7)</sup> |

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*(1)* *For the period from October 7, 2024 (commencement of class operations) through November 30, 2024.* 

*(2)* *Per share amount from net realized gains (losses) was less than 0.01 per share.* 

*(3)* *Assumes investment at net asset value at the beginning of the period, reinvestment of all dividends and distributions, and a complete redemption of the investment at net asset value at the end of the period. The total return is not annualized for periods less than one year.* 

*(4)* *Northern Trust Investments, Inc. voluntarily reimbursed expenses of the Shares class of the Portfolio in the amount of approximately $1,820,000. Total return excluding the voluntary reimbursement would have been 4.18%.* 

*(5)* *Northern Trust Investments, Inc. voluntarily reimbursed expenses of the Shares class of the Portfolio in the amount of approximately $89,000. Total return excluding the voluntary reimbursement would have been 0.68%.* 

*(6)* *Annualized for periods less than one year.* 

*(7)* *As the Portfolio commenced operations of Shares class on October 7, 2024, annualized net investment income ratios may not be reflective of amounts that an investor should expect on an annual basis prospectively.* 

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|:---|:---|:---|
| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS | **27** | MONEY MARKET PORTFOLIOS |

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|:---|:---|
| **FINANCIAL HIGHLIGHTS**  | FOR THE PERIOD ENDED NOVEMBER 30,  |

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| | | |
|:---|:---|:---|
| **TREASURY INSTRUMENTS PORTFOLIO** | **PREMIER** | **PREMIER** |
| **Selected per share data** | **2025** | **2024<sup>(1)</sup>** |
| **Net Asset Value, Beginning of Period** | $1.00 | $1.00 |
| INCOME FROM INVESTMENT OPERATIONS: |  |  |
| Net investment income | 0.04 | 0.02 |
| Net realized gains (losses)<sup>(2)</sup> |  |  |
| &nbsp;&nbsp;&nbsp;&nbsp; Total from Investment Operations | 0.04 | 0.02 |
| LESS DISTRIBUTIONS PAID: |  |  |
| From net investment income | (0.04) | (0.02) |
| &nbsp;&nbsp;&nbsp;&nbsp; Total Distributions Paid | (0.04) | (0.02) |
| Net Asset Value, End of Period | $1.00 | $1.00 |
| **Total Return<sup>(3)</sup>** | 4.27%<sup>(4)</sup> | 2.37%<sup>(5)</sup> |
| SUPPLEMENTAL DATA AND RATIOS: |  |  |
| Net assets, in thousands, end of period | $6084875 | $1708644 |
| Ratio to average net assets of: |  |  |
| &nbsp;&nbsp;&nbsp;&nbsp; Expenses, net of waivers, reimbursements and credits | 0.10% | 0.09%<sup>(6)</sup> |
| &nbsp;&nbsp;&nbsp;&nbsp; Expenses, before waivers, reimbursements and credits | 0.23% | 0.24%<sup>(6)</sup> |
| &nbsp;&nbsp;&nbsp;&nbsp; Net investment income, net of waivers, reimbursements and credits | 4.14% | 4.86%<sup>(6),(7)</sup> |
| &nbsp;&nbsp;&nbsp;&nbsp; Net investment income, before waivers, reimbursements and credits | 4.01% | 4.71%<sup>(6),(7)</sup> |

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*(1)* *For the period from June 11, 2024 (commencement of class operations) through November 30, 2024.* 

*(2)* *Per share amount from net realized gains (losses) was less than 0.01 per share.* 

*(3)* *Assumes investment at net asset value at the beginning of the period, reinvestment of all dividends and distributions, and a complete redemption of the investment at net asset value at the end of the period. The total return is not annualized for periods less than one year.* 

*(4)* *Northern Trust Investments, Inc. voluntarily reimbursed expenses of the Premier class of the Portfolio in the amount of approximately $4,200,000. Total return excluding the voluntary reimbursement would have been 4.13%.* 

*(5)* *Northern Trust Investments, Inc. voluntarily reimbursed expenses of the Premier class of the Portfolio in the amount of approximately $752,000. Total return excluding the voluntary reimbursement would have been 2.30%.* 

*(6)* *Annualized for periods less than one year.* 

*(7)* *As the Portfolio commenced operations of Premier shares on June 11, 2024, annualized net investment income ratios may not be reflective of amounts that an investor should expect on an annual basis prospectively.* 

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| MONEY MARKET PORTFOLIOS | **28** | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS |

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| NORTHERN INSTITUTIONAL FUNDS PROSPECTUS | **31** | MONEY MARKET PORTFOLIOS |

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#### FOR MORE INFORMATION

#### ANNUAL AND SEMI-ANNUAL REPORTS TO SHAREHOLDERS AND FORM N-CSR AND STATEMENT OF ADDITIONAL INFORMATION
Additional information about the Portfolio's investments is available in the Portfolio's annual and semiannual shareholder reports and Form N-CSR. In Form N-CSR, you will find the Portfolio's annual and semi-annual financial statements.

Additional information about the Portfolio and its policies is also available in the Portfolio's SAI. The [SAI](#tx112881_sai) is incorporated by reference into this Prospectus (and is legally considered part of this Prospectus).

The Portfolio's annual and semiannual shareholder reports, the SAI, and other information such as Portfolio financial statements are available free upon request by calling the Northern Institutional Funds Center at 800-637-1380 or by sending an e-mail request to: northern-funds@ntrs.com; or at the website provided below. The SAI and other information are available from a financial intermediary (such as a broker-dealer or bank) through which the Portfolio's shares may be purchased or sold.

#### TO OBTAIN OTHER INFORMATION AND FOR SHAREHOLDER INQUIRIES:

#### BY TELEPHONE
Call 800-637-1380

#### BY MAIL
Northern Institutional Funds

P.O. Box 75986

Chicago, Illinois 60675-5986

#### ON THE INTERNET
The Portfolio's documents are available online and may be downloaded from:

∎ The EDGAR database on the SEC's website at www.sec.gov (text-only).

∎ Northern Institutional Funds website at www.ntam.northerntrust.com/united-states/institutional/strategies/cash/northern-institutional-funds#literature.

Reports and other information about Northern Institutional Funds are available on the EDGAR database on the SEC's internet site at www.sec.gov. You also may obtain copies of Northern Institutional Funds documents, after paying a duplicating fee, by electronic request to: publicinfo@sec.gov.

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| MONEY MARKET PORTFOLIOS | **32** | NORTHERN INSTITUTIONAL FUNDS PROSPECTUS | NIF PRO NDEXX rvsd (3/26) |

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811-03605