[Form 4] First Interstate BancSystem, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Reporting person: The Form 4 was filed by the Susan Scott Heyneman Trust, with Susan Heyneman and First Interstate Wealth Management Co. as co-trustees.

Transaction: On 09/02/2025 the reporting person disposed of 10,000 shares of First Interstate BancSystem, Inc. (FIBK) at a price of $32.28 per share (transaction code S). After the sale the reporting person is reported to beneficially own 519,256 shares, held of record by the trust.

Other details: The filer states that, under certain agreements with other stockholders, the reporting persons may be deemed members of a group and may be deemed to share beneficial ownership of the reported shares, but each disclaims beneficial ownership except to the extent of pecuniary interest.

Positive

• None.

Negative

• Reported disposition of 10,000 shares of FIBK on 09/02/2025 at $32.28 per share, reducing the trust's holdings by that amount

Insights

Financial Analyst

TL;DR: Trustee reported a routine insider sale of 10,000 FIBK shares, leaving a substantial indirect stake of 519,256 shares.

The sale of 10,000 shares at $32.28 is a transparent disclosure of insider activity and reduces the trust's reported holdings by that amount to 519,256 shares held of record. This Form 4 does not include information on intent or timing beyond the single reported sale, nor does it show derivative activity. Without proportion-of-outstanding-share context, the transaction appears to be routine monetization rather than a material shift in control.

Corporate Governance Expert

TL;DR: Filing shows proper Section 16 reporting and highlights a group disclosure that could affect beneficial ownership attribution.

The Form 4 is properly signed and discloses an agreement among certain stockholders that may create group attribution for beneficial ownership purposes. The reporting persons include a disclaimer limiting claimed beneficial ownership to pecuniary interest. From a governance perspective, the disclosure is important because group attribution can affect voting power assessments and future disclosure obligations, even if the current sale itself is limited to 10,000 shares.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees

(Last) (First) (Middle)

P.O. BOX 7113

(Street)

BILLINGS, MT 59116

(City) (State) (Zip)

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)

3. Date of Earliest Transaction (Month/Day/Year)
09/02/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	09/02/2025		S		10,000	D	$32.28	519,256(1)	I	See Footnote(2)

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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

Explanation of Responses:

1. Composed of 519,256 shares held of record by Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees.

2. 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, if any, together with Susan Scott Heyneman, Trust.

	SUSAN SCOTT HEYNEMAN TRUST, SUSAN HEYNEMAN & FIRST INTERSTATE WEALTH MANAGEMENT CO-TRUSTEES, By: /s/ Timothy Leuthold, Attorney-in-Fact for Reporting Person	09/02/2025
	** Signature of Reporting Person	Date
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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

What did the Form 4 for FIBK report on 09/02/2025?

The filing reports a sale of 10,000 shares of First Interstate BancSystem, Inc. at $32.28 per share on 09/02/2025 and shows 519,256 shares held of record by the trust after the sale.

Who filed the Form 4 for FIBK?

The Form 4 was filed by the Susan Scott Heyneman Trust, with Susan Heyneman and First Interstate Wealth Management Co. as co-trustees; the form was signed by Timothy Leuthold as attorney-in-fact.

Does the Form 4 indicate indirect beneficial ownership for FIBK?

Yes. The filing states the 519,256 shares are held of record by the trust and indicates the reporting persons may be deemed members of a group with others under certain agreements, potentially creating indirect beneficial ownership attribution.

Was any derivative activity reported in this Form 4 for FIBK?

No derivative securities or option transactions are reported in Table II of this Form 4; only a non-derivative sale is disclosed.

Does the filing disclose intent or a 10b5-1 plan for the sale?

The Form 4 does not state that the transaction was made pursuant to a 10b5-1 plan and provides no statements of intent beyond the sale details.