X0609 4 2026-09-16 0 0000860413 FIRST INTERSTATE BANCSYSTEM INC FIBK 0001234619 SCOTT JULIE A false P O BOX 7113 BILLINGS MT 59103 0 0 1 0 0001908851 Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002 false P O BOX 7113 BILLINGS MT 59103 0 0 1 0 0001909090 IXL Ltd Liability Co false P O BOX 7113 BILLINGS WY 82836 0 0 1 0 0001909078 Juliana Sarah Scott Rose Trust false PO BOX 7113 BILLINGS MT 59103 0 0 1 0 0001908961 Elizabeth Lauren Scott Rose Trust false PO BOX 7113 BILLINGS MT 59103 0 0 1 0 0 Common Stock 2026-09-16 4 S 0 2700 37.64 D 484309 I See Footnote Composed of 204,166 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02 (which trust effected the reported sale), 35,233 shares held of record by Juliana Sarah Scott Rose Trust, 35,232 shares held of record by Elizabeth Lauren Scott Rose Trust, and 209,678 shares held by IXL Limited Liability Company, over which Ms. Rose has shared voting and dispositive power with a sibling. As a result of certain agreements entered into among the reporting persons, the Issuer, and 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. The reporting persons disclaim beneficial ownership of any such securities, except to the extent of their pecuniary interests 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. 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 2026-09-16 JULIE SCOTT ROSE, By: /s/ Timothy J. Leuthold, Attorney-in-Fact for Reporting Person 2026-09-16 Juliana Sarah Scott Rose Trust, By: / s/ Timothy J. Leuthold, Attorney-in- Fact for Reporting Person 2026-09-16 Elizabeth Lauren Scott Rose Trust, By: / s/ Timothy J. Leuthold, Attorney-in- Fact for Reporting Person 2026-09-16