Sec Form 4 Filing - SCOTT JULIE A @ FIRST INTERSTATE BANCSYSTEM INC - 2023-11-30

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person SCOTT JULIE A 2. Issuer Name and Ticker or Trading Symbol FIRST INTERSTATE BANCSYSTEM INC [ FIBK] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) PO BOX 7113 3. Date of Earliest Transaction (MM/DD/YY) 11/30/2023 (Street) BILLINGS, MT59103 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 11/30/2023 S 10,000 D $ 26.19 ( 1 ) 1,159,700 ( 3 ) I See Footnote ( 2 ) ( 5 ) Common Stock 12/08/2023 S 10,000 D $ 28.42 ( 2 ) 1,149,700 ( 4 ) I See Footnote ( 3 ) ( 5 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other SCOTT JULIE A PO BOX 7113 BILLINGS, MT59103 X Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002 PO BOX 7113 ASHEVILLE, NC59103 X IXL Ltd Liability Co PO BOX 7113 DAYTON, WY82836 X Juliana Sarah Scott Rose Trust PO BOX 7113 BILLINGS, MT59103 X Elizabeth Lauren Scott Rose Trust PO BOX 7113 BILLINGS, MT59103 X Harper Grace Scott Trust PO BOX 7113 BILLINGS, MT59103 X Harrison William Scott Trust PO BOX 7113 BILLINGS, MT59103 X Holland Elizabeth Scott Trust PO BOX 7113 BILLINGS, MT59103 X Signatures Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002, By: + /s/ Timothy J. Leuthold, Attorney-in-Fact for Reporting Person 12/19/2023 Signature of Reporting Person Date JULIE SCOTT ROSE, /s/ Timothy J. Leuthold, Attorney-in-Fact for Reporting Person 12/19/2023 Signature of Reporting Person Date IXL LIMITED LIABILITY COMPANY, By: + /s/ Timothy J. Leuthold, Attorney-in-Fact for Reporting Person 12/19/2023 Signature of Reporting Person Date Juliana Sarah Scott Rose Trust, By: + /s/ Timothy J. Leuthold, Attorney-in-Fact for Reporting Person 12/19/2023 Signature of Reporting Person Date Elizabeth Lauren Scott Rose Trust, By: + /s/ Timothy J. Leuthold, Attorney-in-Fact for Reporting Person 12/19/2023 Signature of Reporting Person Date Harper Grace Scott Trust, By: + /s/ Timothy J. Leuthold, Attorney-in-Fact for Reporting Person 12/19/2023 Signature of Reporting Person Date Harrison William Scott Trust, By: + /s/ Timothy J. Leuthold, Attorney-in-Fact for Reporting Person 12/19/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The price reported in column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $26.03 to $26.29. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holders of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon request, the full information regarding the number of shares sold at each separate price within the ranges set forth above. ( 2 )The price reported in column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $28.27 to $28.51. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holders of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon request, the full information regarding the number of shares sold at each separate price within the ranges set forth above. ( 3 )Composed of 530,281 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 209,678 shares held of record by IXL Limited Liability Company, 58,537 shares held of record by Holland Elizabeth Scott Trust, 58,537 shares held of record by Harper GraceScott Trust, 58,538 shares held of record by Harrison William Scott Trust, 122,065 shares held of record by Juliana Sarah Scott Rose Trust, 122,064 shares held of record by Elizabeth Lauren Scott Rose Trust. ( 4 )Composed of 520,281 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 209,678 shares held of record by IXL Limited Liability Company, 58,537 shares held of record by Holland Elizabeth Scott Trust, 58,537 shares held of record by Harper GraceScott Trust, 58,538 shares held of record by Harrison William Scott Trust, 122,065 shares held of record by Juliana Sarah Scott Rose Trust, 122,064 shares held of record by Elizabeth Lauren Scott Rose Trust. ( 5 )As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Julie Scott Rose with the indication of direct or indirect ownership in Table I and Table II being made from Julie Scott Rose's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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