| Name | Relationship | Address | Signature | Signature date | CIK |
|---|---|---|---|---|---|
| HEYNEMAN JOHN M JR | Director, 10%+ Owner | P.O. BOX 30918, BILLINGS | /s/ Kirk D. Jensen, Attorney-in-Fact for Reporting Person | 18 Aug 2025 | 0001198518 |
| John M Heyneman Jr. Trust | 10%+ Owner | P.O. BOX 7113, BILLINGS | RIKI RAE SCOTT DAVIDSON & JOHN HEYNEMAN JR., TRUSTEES FBO RIKI SCOTT DAVIDSON EXEMPTION TRUST UNDER THE SCOTT FAMILY 1996 TRUST, By:** | 18 Aug 2025 | 0001908848 |
| Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust | 10%+ Owner | P.O. BOX 7113, BILLINGS | RAE ANN MORSS & JOHN HEYNEMAN JR., TRUSTEES FBO RAE ANN MORSS EXEMPTION TRUST UNDER THE SCOTT FAMILY 1996 TRUST, By:** | 18 Aug 2025 | 0001908849 |
| Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust | 10%+ Owner | P.O. BOX 7113, BILLINGS | TOWANDA INVESTMENTS LIMITED PARTNERSHIP, By:** | 18 Aug 2025 | 0001908784 |
| Towanda Investments Limited Partnership | 10%+ Owner | P.O. BOX 7113, BILLINGS | JOHN M HEYNEMAN JR. TRUST, By** | 18 Aug 2025 | 0001908810 |
| Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Ownership | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| transaction | FIBK | Common Stock | Sale | $356,726 | -11,818 | -69% | $30.18 | 5,224 | 14 Aug 2025 | Direct | F1 |
| holding | FIBK | Common Stock | 1,414,636 | 14 Aug 2025 | see footnote | F2, F3 |
| Id | Content |
|---|---|
| F1 | The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.07 to $30.23. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder 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. |
| 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 and 5, if any, together with John Heyneman, Jr. with the indication of direct or indirect ownership in Table I being made from John Heyneman, Jr.'s perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons. |
| F3 | Composed of 150,000 shares held of record by John M Heyneman Jr. Trust, 85,836 shares held of record by Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust, 85,836 shares held of record by Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust, 1,085,792 shares held of record by Towanda Investments Limited Partnership, 4,552 shares held of record by John Heyneman, Jr.'s spouse, 1095 shares held of record by John Heyneman, Jr.'s daughter, 1,215 shares held of record by John Heyneman, Jr.'s son Quinn, and 310 shares held of record by John Heyneman, Jr.'s son Bae-John. |