FIRST INTERSTATE BANCSYSTEM INC

Delinquent Section 16(a) Reports

Section 16(a) of the Exchange Act requires our directors and executive officers, and persons who own

more than 10% of our common stock, to file with the SEC initial reports of ownership and reports of

changes in ownership of our common stock and other equity securities. Executive officers, directors,

and greater than 10% shareholders are required by SEC regulations to furnish us with copies of all

Section 16(a) forms they file.

To our knowledge, during the year ended December 31, 2024, all of our directors, executive officers,

and greater than 10% shareholders complied with all Section 16(a) filing requirements, except that: (1)

one report with respect to one gift transaction effected by Ms. Risa Scott was not timely filed.

Shareholder Proposals

The rules of the SEC permit eligible shareholders of a company, after timely notice to the company, to

present proposals for shareholder action in the company’s proxy statement where such proposals are

consistent with applicable law, pertain to matters appropriate for shareholder action, and are not

properly omitted by company action in accordance with the SEC’s proxy rules. The deadline for

submission of shareholder proposals pursuant to Rule 14a-8 under the Exchange Act for inclusion in our

proxy statement for our 2026 annual meeting is December 9, 2025, which is 120 days prior to the

anniversary of the mailing date for our proxy materials for this year’s annual meeting.

Additionally, under the terms of our bylaws, shareholders who wish to present an item of business or

nominate a director at the 2026 annual meeting, but does not seek to include such item of business or

director nominee in our proxy statement for the 2026 annual meeting, must provide notice to the

corporate secretary at our principal executive offices not later than 5:00 p.m., local time, on the 90th

day (February 19, 2026), nor earlier than 8:00 a.m., local time, on the 120th day (January 20, 2026),

prior to May 20, 2026, which will be the one-year anniversary of our 2025 annual meeting. In the event

that no annual meeting of shareholders was held in the preceding year, or the date of the applicable

annual meeting has been changed by more than 30 days from the day of the first anniversary of the

preceding year’s annual meeting, then, to be timely, such notice must be received by the corporate

secretary at our principal executive offices no earlier than 8:00 a.m., local time, on the 120th day

prior to the day of the annual meeting and no later than 5:00 p.m., local time, on the 10th day

following the day on which public announcement of the date of the annual meeting was first made. In

the event that a special meeting of shareholders is called for the election of directors, nomination by a

shareholder of record (on the date the notice is provided, on the record date and on the date of the

special meeting) must be delivered to the corporate secretary at our principal executive offices of the

Company and received no earlier than 8:00 a.m., local time, on the 120th day prior to the date of the

special meeting and no later than 5:00 p.m., local time, on the 10th day following the day on which

public disclosure is first made of the date of the special meeting. If we do not receive notice of a

shareholder proposal within that period of time, such proposal will be considered untimely pursuant to

Rules 14a-4 and 14a-5(e) and the persons named in proxies solicited by the Board for our 2026 annual

meeting may exercise discretionary voting power with respect to such proposal and/or the Chair may

consider the matter out of order and not address it at the meeting at all. The notice must also contain

the information required by our bylaws, and the shareholder(s) must comply with the information and

other requirements set forth in our bylaws with respect to such proposals. A shareholder providing

notice of any business at a shareholder meeting, other than the nomination for election or reelection

of a person as a Director to the Board (“Proposed Nominee”), must provide a reasonably brief

description of the business desired to be brought before the shareholder meeting, including the text of

any such proposal, the reasons for conducting such business at the shareholder meeting, and all other

information relating to such business that would be required to be disclosed in a proxy statement or

other filing required to be made. The information provided must include all information that would be

necessary for inclusion under Section 14 of the Exchange Act and the rules and regulations promulgated

thereunder.

A shareholder providing notice of a nomination of a Proposed Nominee to the Board is required to set

forth, as to each Proposed Nominee:

•basic biographical information about each Proposed Nominee including their name, age,

business address, residence address, and principal occupation;

•the class and number of shares of the Company that are held of record or are beneficially

owned by Proposed Nominee and a description of any derivative instruments held or

beneficially owned thereby or of any other agreement or arrangement the effect or intent of

which is to mitigate loss to, or to manage the risk or benefit from, changes in the price of any

shares of the Company, or maintain, increase or decrease the voting power of such Proposed

Nominee held or beneficially owned thereby or of any other agreement or arrangement the

effect or intent of which is to mitigate loss to, or to manage the risk or benefit from, changes

in the price of any shares of the Company, or maintain, increase or decrease the voting power

of such Proposed Nominee;

•information related to the Proposed Nominee and its affiliates or associates that would be

required to be disclosed in a proxy statement or filing required to be made by the stockholder

or their associates in connection with the solicitations of proxies for the election of directors

required pursuant to Section 14 of the Exchange Act and the rules and regulations promulgated

thereunder (collectively, the “Proxy Rules”);

•the Proposed Nominee’s written consent to being named in the applicable proxy statement and

to serving as a director of the Company if elected;

•a reasonably detailed description of any direct or indirect material relationships, or any

agreements, arrangements, or understandings, whether compensatory, payment,

indemnification or other, that a Proposed Nominee has, or has had within the past three years,

with the noticing stockholder or their associates;

•a description of any business or personal interests of the Proposed Nominee that could be

reasonably expected to cause a conflict of interest with the Company or its affiliates; and

•information regarding the relationship and any agreement or arrangements between the

Proposed Nominee and the shareholder submitting the nomination.

In addition, a Proposed Nominee must also provide a signed written questionnaire containing

information regarding such Proposed Nominee’s background and qualifications and such other

information as may reasonably be required to determine their eligibility to serve as a director or

independent director of the Company. The Company also requires the Proposed Nominee to provide

various written representations and undertakings pertaining to, among other things, the Proposed

Nominee’s fiduciary obligations, compliance obligations with applicable laws, rules, regulations, and

Company policies, outside arrangements impacting voting, and that the information provided is

accurate and complete in all material respects. The Proposed Nominee must also agree that they

intend to fulfill the full term on the Board, if elected, and will resign as Director if the Board

determines that the Director has not complied with the various requirements in our bylaws.

As to the shareholder giving the notice, the shareholder and any “Stockholder Associated Person” as

such term is described in our bylaws, must also provide additional information about such shareholder

and associated person, including but not limited to:

•background biographical information such as name and address (as they appear in the

Company’s books and records) and any class, series, and number of shares of securities of the

Company, directly or indirectly, regardless of whether they are owned beneficially and/or of

record by the shareholder and each associated person, in the name of a nominee holder, or by a

third party entity;

•a description of all rights to dividends that are separated or separable from the underlying

security;

•any significant equity interests or any derivative instruments held in any principal competitor of

the Company by the shareholder or any associated person;

•any direct or indirect interest of the shareholder or any Stockholder Associated Person in any

agreement, arrangement or understanding, written or oral, with the Company, any affiliate of

the Company or any principal competitor of the Company and a written representation

regarding any breach of such agreements, arrangements, or understandings;

•a description of any material interest in the business proposed, or the election of any Proposed

Nominee;

•whether the shareholder or any associated person has complied, and will comply, with all

applicable requirements of state law and the Exchange Act with respect to shareholder

proposals;

•a complete and accurate description of any performance-related fees or other compensation

related to the Company’s securities;

•a description of the investment strategies or objectives of the shareholder as they relate to the

Company and a copy of any presentation, document or marketing material provided to third

parties regarding the same;

•all information that would be required to be set forth in a Schedule 13D filed with the SEC if

such a statement were required to be filed by such shareholder or any associated person with

respect to the Company (regardless of whether such person or entity is actually required to file

a Schedule 13D);

•a certification that the shareholder and associated persons have complied with all applicable

federal, state and other legal requirements in connection with investment activities related to

the Company;

•if the shareholder (or the beneficial owner(s) on whose behalf such shareholder is submitting a

notice to the Company) is not a natural person, the identity and certain background information

on each natural person responsible for the formulation of and decision to propose the business

or nomination to be brought before the meeting;

•a representation from such shareholder as to whether the shareholder or any associated person

intends or is part of a group which intends (1) to solicit proxies in support of the election of any

Proposed Nominee in accordance with Rule 14a-19 under the Exchange Act or (2) to engage in a

solicitation (within the meaning of Exchange Act Rule 14a-1(l)) with respect to the nomination

or other business, as applicable, and if so, the name of each participant (as defined in Item 4 of

Schedule 14A under the Exchange Act) in such solicitation;

•a representation that such shareholder is a holder of record of stock of the Company entitled to

vote at such meeting and that such shareholder intends to appear in person, or by proxy, at the

meeting to nominate the person or persons named in the notice;

•a complete and accurate description of any known pending or threatened legal proceeding

involving the shareholder or any associated persons and the Company or any current or former

officer, director, affiliate or associate of the Company;

•identification of the names and addresses of other shareholders (including beneficial owners)

known to support the nomination(s) or other business proposal(s) submitted by the shareholder;

and

•any other information relating to such shareholder or any associated person that would be

required to be disclosed in a proxy statement or other filings required to be made with the SEC

in connection with the solicitations of proxies for the election of directors pursuant to

securities rules and regulations.

A shareholder is required to update the information provided in any such notice if it is not true and

correct and must do so within time periods prescribed within our bylaws or such information could be

deemed to have not been provided in accordance with the provisions of our bylaws.

Any notice of director nomination submitted to the Company must contain the information required by

our bylaws, including the information required by Rule 14a-19 of the Exchange Act in the case of a

shareholder who intends to solicit proxies in support of director nominees other than the Company’s

nominees at the 2026 annual meeting.

Forward Looking Statements

This document includes forward-looking statements within the meaning of the Private Securities

Litigation Reform Act of 1995, including statements regarding our goals, commitments, and strategies

and our executive compensation program. These statements involve risks and uncertainties. Actual

results could differ materially from any future results expressed or implied by the forward-looking

statements for a variety of reasons, including due to the risks, uncertainties, and other important

factors that are discussed in our most recently filed periodic reports on Form 10-K and Form 10-Q and

subsequent filings. We assume no obligation to update any forward-looking statements, which speak

only as of the date they are made.

Other Matters

We know of no matters other than as contained in the Notice of Annual Meeting of Shareholders to be

brought before the meeting. The enclosed proxy, however, gives discretionary authority for the proxy

holders to vote on your behalf in the event that any additional matters should be duly presented.

Any shareholder may obtain without charge a copy of our Annual Report, which includes our 2024 Form

10-K containing our audited financial statements. Written requests for a copy of our Annual Report

should be addressed to Investor Relations, First Interstate BancSystem, Inc., P.O. Box 30918, Billings,

Montana 59116-0918.

BY ORDER OF THE BOARD OF DIRECTORS

Kirk D. Jensen

General Counsel and Corporate Secretary

Billings, Montana

April 8, 2025