FIRST INTERSTATE BANCSYSTEM INC — Director's Dealing 2025

Aug 1, 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: FIRST INTERSTATE BANCSYSTEM INC (FIBK)
CIK: 0000860413
Period of Report: 2025-08-01

Reporting Person: Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-08-01	Common Stock	S	55000	$27.86	Disposed	529256	Indirect

Footnotes

F1: Composed of 529,256 shares held of record by Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees.

F2: 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.

F3: The price reported in column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging form $27.60 to $28.28. 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.