FIBK

SEC source: 0000860413-25-000034 · wk-form4_1742337262.xml · nonDerivative · entry 3

Robbins Kristina · CIK 0001930719 · EVP, Chief Operations Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 17,145

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000034 · wk-form4_1742337262.xml · nonDerivative · entry 2

Robbins Kristina · CIK 0001930719 · EVP, Chief Operations Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 17,534

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000028 · wk-form4_1742336228.xml · nonDerivative · entry 5

Meyer Lori · CIK 0002003084 · EVP, Chief Information Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 12,808

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000028 · wk-form4_1742336228.xml · nonDerivative · entry 4

Meyer Lori · CIK 0002003084 · EVP, Chief Information Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,231

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000028 · wk-form4_1742336228.xml · nonDerivative · entry 3

Meyer Lori · CIK 0002003084 · EVP, Chief Information Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,307

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000028 · wk-form4_1742336228.xml · nonDerivative · entry 2

Meyer Lori · CIK 0002003084 · EVP, Chief Information Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,463

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000026 · wk-form4_1742335972.xml · nonDerivative · entry 5

Jensen Kirk D · CIK 0001697127 · General Counsel

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 30,155

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000026 · wk-form4_1742335972.xml · nonDerivative · entry 4

Jensen Kirk D · CIK 0001697127 · General Counsel

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 30,736

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000026 · wk-form4_1742335972.xml · nonDerivative · entry 3

Jensen Kirk D · CIK 0001697127 · General Counsel

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,099

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000026 · wk-form4_1742335972.xml · nonDerivative · entry 2

Jensen Kirk D · CIK 0001697127 · General Counsel

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,627

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000024 · wk-form4_1742335685.xml · nonDerivative · entry 5

Asker Lorrie F · CIK 0001965779 · Chief Banking Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 19,708

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000024 · wk-form4_1742335685.xml · nonDerivative · entry 4

Asker Lorrie F · CIK 0001965779 · Chief Banking Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 20,554

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000024 · wk-form4_1742335685.xml · nonDerivative · entry 3

Asker Lorrie F · CIK 0001965779 · Chief Banking Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 20,811

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000024 · wk-form4_1742335685.xml · nonDerivative · entry 2

Asker Lorrie F · CIK 0001965779 · Chief Banking Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 21,129

F2 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000074 · wk-form4_1748625714.xml · nonDerivative · entry 6

Scott James R. Jr · CIK 0001675872 · Director · 10% owner

First Interstate Bank TTEE for Dana S Andersson GST Exempt Trust No 1 Dtd 12/11/2020 · CIK 0001910215 · 10% owner

First Interstate Bank TTEE for James R Scott Jr. GST Exempt Trust No 1 Dtd 12/11/2020 · CIK 0001910352 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 75,599

F3 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of restricted stock units.

SEC source: 0000860413-25-000074 · wk-form4_1748625714.xml · nonDerivative · entry 5

Scott James R. Jr · CIK 0001675872 · Director · 10% owner

First Interstate Bank TTEE for Dana S Andersson GST Exempt Trust No 1 Dtd 12/11/2020 · CIK 0001910215 · 10% owner

First Interstate Bank TTEE for James R Scott Jr. GST Exempt Trust No 1 Dtd 12/11/2020 · CIK 0001910352 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 77,345

F3 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of restricted stock units.

SEC source: 0000860413-25-000034 · wk-form4_1742337262.xml · nonDerivative · entry 1

Robbins Kristina · CIK 0001930719 · EVP, Chief Operations Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 17,685

F1 · shares: Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vest in three equal annual installments beginning on March 15, 2026, subject to the reporting person's continued employment through each applicable vesting date.

SEC source: 0000860413-25-000032 · wk-form4_1742337056.xml · nonDerivative · entry 1

Reuter James A · CIK 0002042435 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 60,637

F1 · shares: Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vest in three equal annual installments beginning on March 15, 2026, subject to the reporting person's continued employment through each applicable vesting date.

SEC source: 0000860413-25-000030 · wk-form4_1742336862.xml · nonDerivative · entry 1

Mutch Marcy D · CIK 0001653911 · Exec. Vice Pres. & CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 69,608

F1 · shares: Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units are vested upon grant date as the reporting person has reached retirement age.

SEC source: 0000860413-25-000028 · wk-form4_1742336228.xml · nonDerivative · entry 1

Meyer Lori · CIK 0002003084 · EVP, Chief Information Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,534

F1 · shares: Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vest in three equal annual installments beginning on March 15, 2026, subject to the reporting person's continued employment through each applicable vesting date.

SEC source: 0000860413-25-000026 · wk-form4_1742335972.xml · nonDerivative · entry 1

Jensen Kirk D · CIK 0001697127 · General Counsel

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,857

F1 · shares: Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vest in three equal annual installments beginning on March 15, 2026, subject to the reporting person's continued employment through each applicable vesting date.

SEC source: 0000860413-25-000024 · wk-form4_1742335685.xml · nonDerivative · entry 1

Asker Lorrie F · CIK 0001965779 · Chief Banking Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 21,258

F1 · shares: Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vest in three equal annual installments beginning on March 15, 2026, subject to the reporting person's continued employment through each applicable vesting date.

SEC source: 0000860413-25-000074 · wk-form4_1748625714.xml · nonDerivative · entry 4

Scott James R. Jr · CIK 0001675872 · Director · 10% owner

First Interstate Bank TTEE for Dana S Andersson GST Exempt Trust No 1 Dtd 12/11/2020 · CIK 0001910215 · 10% owner

First Interstate Bank TTEE for James R Scott Jr. GST Exempt Trust No 1 Dtd 12/11/2020 · CIK 0001910352 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 77,368

F4 · shares: Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's Equity and Incentive Plan, which units are scheduled to vest in three equal annual installments beginning on March 15, 2026, subject to the reporting person's continued employment through each applicable vesting date.

SEC source: 0000860413-25-000019 · wk-form4_1740614037.xml · nonDerivative · entry 1

HEYNEMAN JOHN M JR · CIK 0001198518 · Director · 10% owner

John M Heyneman Jr. Trust · CIK 0001908848 · 10% owner

Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908849 · 10% owner

Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908784 · 10% owner

Towanda Investments Limited Partnership · CIK 0001908810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · see footnote

Disclosed balance after: 1,414,636

F1 · ownership.nature: 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.

F2 · ownership.nature: 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.

SEC source: 0000860413-25-000012 · wk-form4_1739923106.xml · nonDerivative · entry 1

HEYNEMAN JOHN M JR · CIK 0001198518 · Director · 10% owner

John M Heyneman Jr. Trust · CIK 0001908848 · 10% owner

Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908849 · 10% owner

Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908784 · 10% owner

Towanda Investments Limited Partnership · CIK 0001908810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · see footnote

Disclosed balance after: 1,414,886

F1 · ownership.nature: 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.

F2 · ownership.nature: 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, 1,465 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.

SEC source: 0000860413-25-000010 · wk-form4_1739320334.xml · nonDerivative · entry 1

Asker Lorrie F · CIK 0001965779 · Chief Banking Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 14,546

F1 · shares: Disposition to the issuer of issuer securities in payment of minimum required withholding taxes due upon vesting of unvested shares.

SEC source: 0000860413-25-000008 · wk-form4_1739211758.xml · nonDerivative · entry 2

HEYNEMAN JOHN M JR · CIK 0001198518 · Director · 10% owner

John M Heyneman Jr. Trust · CIK 0001908848 · 10% owner

Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908849 · 10% owner

Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908784 · 10% owner

Towanda Investments Limited Partnership · CIK 0001908810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · see footnote

Disclosed balance after: 1,416,221

F1 · kind: Shares disposed of by John M Heyneman Jr. to John M. Heyneman Jr.'s son, and shares acquired by John M. Heynman Jr.'s son as a bona fide gift.

F2 · ownership.nature: 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 · ownership.nature: 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, 1,095 shares held of record by John Heyneman, Jr.'s daughter, 1,465 shares held of record by John Heyneman, Jr.'s son Quinn, and 1,645 shares held of record by John Heyneman, Jr.'s son Bae-John.

SEC source: 0000860413-25-000008 · wk-form4_1739211758.xml · nonDerivative · entry 1

HEYNEMAN JOHN M JR · CIK 0001198518 · Director · 10% owner

John M Heyneman Jr. Trust · CIK 0001908848 · 10% owner

Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908849 · 10% owner

Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908784 · 10% owner

Towanda Investments Limited Partnership · CIK 0001908810 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 14,096

F1 · kind: Shares disposed of by John M Heyneman Jr. to John M. Heyneman Jr.'s son, and shares acquired by John M. Heynman Jr.'s son as a bona fide gift.

SEC source: 0000860413-24-000138 · wk-form4_1734126366.xml · nonDerivative · entry 4

SCOTT JAMES R · CIK 0001198533 · Director · 10% owner

James R Scott Trust, James R Scott & First Interstate Wealth Management Co-TTEEs · CIK 0001908712 · 10% owner

J.S. Investments Limited Partnership · CIK 0001506291 · 10% owner

James R & Christine M Scott Foundation · CIK 0001909853 · 10% owner

Foundation for Community Vitality · CIK 0001908742 · 10% owner

James F Heyneman Conservatorship, James Scott, Conservator · CIK 0001908854 · 10% owner

James F Heyneman Trust, James Scott & First Interstate Wealth Management Co-Trustees · CIK 0001908844 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · see footnote

Disclosed balance after: 4,388,016

F4 · balance_after: Shares disposed of by James R. Scott Trust, James R Scott & First Interstate Wealth Managment Co-TTEEs's to Foundation for Community Vitality, and shares acquired by Foundation for Community Vitality from James R. Scott Trust, James R Scott & First Interstate Wealth Managment Co-TTEEs's, as a bona fide gift.

F2 · ownership.nature: 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 James R. Scott with the indication of direct or indirect ownership in Tables I and II being made from James R. Scott's perspective unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

F3 · ownership.nature: Composed of 1,969,304 shares held of record by James R Scott Trust, James R Scott & First Interstate Wealth Management Co-TTEEs, 15,660 shares held of record by James R Scott's 401k, 35,240 shares held of record by James R and Christine M Scott Foundation, 1,901,036 shares held of record by JS Investments Limited Partnership, 345,053 shares held of record by Foundation for Community Vitality, 73,002 shares held of record by James F Heyneman Conservatorship, James Scott, Conservator, 7,096 shares held of record by James F Heyneman Trust, James Scott & First Interstate Wealth Management Co-Trustees, and 41,625 shares held of record by James R. Scott's spouse.

SEC source: 0000860413-24-000138 · wk-form4_1734126366.xml · nonDerivative · entry 3

SCOTT JAMES R · CIK 0001198533 · Director · 10% owner

James R Scott Trust, James R Scott & First Interstate Wealth Management Co-TTEEs · CIK 0001908712 · 10% owner

J.S. Investments Limited Partnership · CIK 0001506291 · 10% owner

James R & Christine M Scott Foundation · CIK 0001909853 · 10% owner

Foundation for Community Vitality · CIK 0001908742 · 10% owner

James F Heyneman Conservatorship, James Scott, Conservator · CIK 0001908854 · 10% owner

James F Heyneman Trust, James Scott & First Interstate Wealth Management Co-Trustees · CIK 0001908844 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · see footnote

Disclosed balance after: 4,387,289

F4 · balance_after: Shares disposed of by James R. Scott Trust, James R Scott & First Interstate Wealth Managment Co-TTEEs's to Foundation for Community Vitality, and shares acquired by Foundation for Community Vitality from James R. Scott Trust, James R Scott & First Interstate Wealth Managment Co-TTEEs's, as a bona fide gift.

F2 · ownership.nature: 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 James R. Scott with the indication of direct or indirect ownership in Tables I and II being made from James R. Scott's perspective unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

F3 · ownership.nature: Composed of 1,969,304 shares held of record by James R Scott Trust, James R Scott & First Interstate Wealth Management Co-TTEEs, 15,660 shares held of record by James R Scott's 401k, 35,240 shares held of record by James R and Christine M Scott Foundation, 1,901,036 shares held of record by JS Investments Limited Partnership, 345,053 shares held of record by Foundation for Community Vitality, 73,002 shares held of record by James F Heyneman Conservatorship, James Scott, Conservator, 7,096 shares held of record by James F Heyneman Trust, James Scott & First Interstate Wealth Management Co-Trustees, and 41,625 shares held of record by James R. Scott's spouse.

SEC source: 0000860413-24-000138 · wk-form4_1734126366.xml · nonDerivative · entry 2

SCOTT JAMES R · CIK 0001198533 · Director · 10% owner

James R Scott Trust, James R Scott & First Interstate Wealth Management Co-TTEEs · CIK 0001908712 · 10% owner

J.S. Investments Limited Partnership · CIK 0001506291 · 10% owner

James R & Christine M Scott Foundation · CIK 0001909853 · 10% owner

Foundation for Community Vitality · CIK 0001908742 · 10% owner

James F Heyneman Conservatorship, James Scott, Conservator · CIK 0001908854 · 10% owner

James F Heyneman Trust, James Scott & First Interstate Wealth Management Co-Trustees · CIK 0001908844 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · see footnote

Disclosed balance after: 4,388,016

F1 · balance_after: Shares disposed of by James R. Scott's spouse to Foundation for Community Vitality, and shares acquired by Foundation for Community Vitality from James R. Scott's spouse as a bona fide gift.

F2 · ownership.nature: 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 James R. Scott with the indication of direct or indirect ownership in Tables I and II being made from James R. Scott's perspective unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

F3 · ownership.nature: Composed of 1,969,304 shares held of record by James R Scott Trust, James R Scott & First Interstate Wealth Management Co-TTEEs, 15,660 shares held of record by James R Scott's 401k, 35,240 shares held of record by James R and Christine M Scott Foundation, 1,901,036 shares held of record by JS Investments Limited Partnership, 345,053 shares held of record by Foundation for Community Vitality, 73,002 shares held of record by James F Heyneman Conservatorship, James Scott, Conservator, 7,096 shares held of record by James F Heyneman Trust, James Scott & First Interstate Wealth Management Co-Trustees, and 41,625 shares held of record by James R. Scott's spouse.

SEC source: 0000860413-24-000138 · wk-form4_1734126366.xml · nonDerivative · entry 1

SCOTT JAMES R · CIK 0001198533 · Director · 10% owner

James R Scott Trust, James R Scott & First Interstate Wealth Management Co-TTEEs · CIK 0001908712 · 10% owner

J.S. Investments Limited Partnership · CIK 0001506291 · 10% owner

James R & Christine M Scott Foundation · CIK 0001909853 · 10% owner

Foundation for Community Vitality · CIK 0001908742 · 10% owner

James F Heyneman Conservatorship, James Scott, Conservator · CIK 0001908854 · 10% owner

James F Heyneman Trust, James Scott & First Interstate Wealth Management Co-Trustees · CIK 0001908844 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · see footnote

Disclosed balance after: 4,387,289

F1 · balance_after: Shares disposed of by James R. Scott's spouse to Foundation for Community Vitality, and shares acquired by Foundation for Community Vitality from James R. Scott's spouse as a bona fide gift.

F2 · ownership.nature: 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 James R. Scott with the indication of direct or indirect ownership in Tables I and II being made from James R. Scott's perspective unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

F3 · ownership.nature: Composed of 1,969,304 shares held of record by James R Scott Trust, James R Scott & First Interstate Wealth Management Co-TTEEs, 15,660 shares held of record by James R Scott's 401k, 35,240 shares held of record by James R and Christine M Scott Foundation, 1,901,036 shares held of record by JS Investments Limited Partnership, 345,053 shares held of record by Foundation for Community Vitality, 73,002 shares held of record by James F Heyneman Conservatorship, James Scott, Conservator, 7,096 shares held of record by James F Heyneman Trust, James Scott & First Interstate Wealth Management Co-Trustees, and 41,625 shares held of record by James R. Scott's spouse.

SEC source: 0001641172-25-020230 · ownership.xml · nonDerivative · entry 4

Scott Jeremy · CIK 0001803925 · Director · 10% owner

Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15 · CIK 0001909124 · 10% owner

NBAR5 Limited Partnership · CIK 0002076804 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnote

Disclosed balance after: 3,489,305

F4 · balance_after: Includes these 475 shares received by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15 as a gift from a family member.

F4 · ownership.nature: Includes these 475 shares received by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15 as a gift from a family member.

F5 · ownership.nature: As a result of agreements entered into among the reporting persons, the issuer, and other stockholders of the issuer signatory thereto, the reporting persons may be deemed members of a group with the other signatories to the agreement 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 his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with the indication of direct or indirect ownership in Tables I and II being made from Jeremy Scott's perspective, unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

SEC source: 0001641172-25-020230 · ownership.xml · nonDerivative · entry 3

Scott Jeremy · CIK 0001803925 · Director · 10% owner

Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15 · CIK 0001909124 · 10% owner

NBAR5 Limited Partnership · CIK 0002076804 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnote

Disclosed balance after: 3,488,830

F3 · balance_after: Includes these 475 shares received by Jeremy Scott's spouse as a gift from a family member.

F3 · ownership.nature: Includes these 475 shares received by Jeremy Scott's spouse as a gift from a family member.

F5 · ownership.nature: As a result of agreements entered into among the reporting persons, the issuer, and other stockholders of the issuer signatory thereto, the reporting persons may be deemed members of a group with the other signatories to the agreement 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 his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with the indication of direct or indirect ownership in Tables I and II being made from Jeremy Scott's perspective, unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

SEC source: 0001493152-26-007141 · ownership.xml · nonDerivative · entry 3

Scott Geoffrey D · CIK 0002022652 · 10% owner

10b5-1 filing: No plan indicated

Ownership: Indirect · By Spouse

Disclosed balance after: 2,675

F2 · balance_after: End of period holdings previously reported on a Form 4 filed on December 10, 2025, was inadvertently underreported by 60 shares due to a scrivener's error.

SEC source: 0001493152-24-047565 · ownership.xml · nonDerivative · entry 1

Scott James R. Jr · CIK 0001675872 · 10% owner

First Interstate Bank TTEE for Dana S Andersson GST Exempt Trust No 1 Dtd 12/11/2020 · CIK 0001910215 · 10% owner

First Interstate Bank TTEE for James R Scott Jr. GST Exempt Trust No 1 Dtd 12/11/2020 · CIK 0001910352 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 75,387

SEC source: 0000860413-24-000136 · wk-form4_1731621646.xml · nonDerivative · entry 2

Scott Jonathan R · CIK 0001361935 · Director · 10% owner

Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04 · CIK 0001908962 · 10% owner

Harrison William Scott Trust · CIK 0001908873 · 10% owner

Harper Grace Scott Trust · CIK 0001908895 · 10% owner

Holland Elizabeth Scott Trust · CIK 0001908953 · 10% owner

IXL Ltd Liability Co · CIK 0001909090 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 958,710

F4 · price: The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $34.11 to $34.30. 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.

F3 · ownership.nature: 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 Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

F5 · ownership.nature: Composed of 589,372 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 50,000 shares held of record by Jonathan Scott's spouse.

SEC source: 0001493152-24-044912 · ownership.xml · nonDerivative · entry 2

SCOTT JULIE A · CIK 0001234619 · 10% owner

Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002 · CIK 0001908851 · 10% owner

IXL Ltd Liability Co · CIK 0001909090 · 10% owner

Juliana Sarah Scott Rose Trust · CIK 0001909078 · 10% owner

Elizabeth Lauren Scott Rose Trust · CIK 0001908961 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 613,019

F2 · balance_after: Composed of 223,216 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust, 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.

F2 · ownership.nature: Composed of 223,216 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust, 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.

F3 · ownership.nature: 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.

SEC source: 0000860413-24-000136 · wk-form4_1731621646.xml · nonDerivative · entry 1

Scott Jonathan R · CIK 0001361935 · Director · 10% owner

Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04 · CIK 0001908962 · 10% owner

Harrison William Scott Trust · CIK 0001908873 · 10% owner

Harper Grace Scott Trust · CIK 0001908895 · 10% owner

Holland Elizabeth Scott Trust · CIK 0001908953 · 10% owner

IXL Ltd Liability Co · CIK 0001909090 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 965,210

F1 · price: The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $33.64 to $34.18. 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 · ownership.nature: Composed of 595,872 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 50,000 shares held of record by Jonathan Scott's spouse.

F3 · ownership.nature: 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 Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons.

SEC source: 0001493152-24-044912 · ownership.xml · nonDerivative · entry 1

SCOTT JULIE A · CIK 0001234619 · 10% owner

Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002 · CIK 0001908851 · 10% owner

IXL Ltd Liability Co · CIK 0001909090 · 10% owner

Juliana Sarah Scott Rose Trust · CIK 0001909078 · 10% owner

Elizabeth Lauren Scott Rose Trust · CIK 0001908961 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 635,069

F1 · balance_after: Composed of 223,216 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 43,903 shares held of record by Holland Elizabeth Scott Trust, 43,903 shares held of record by Harper Grace Scott Trust, 43,904 shares held of record by Harrison William Scott Trust, 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.

F1 · ownership.nature: Composed of 223,216 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 43,903 shares held of record by Holland Elizabeth Scott Trust, 43,903 shares held of record by Harper Grace Scott Trust, 43,904 shares held of record by Harrison William Scott Trust, 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.

F3 · ownership.nature: 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.

SEC source: 0001493152-24-044332 · ownership.xml · nonDerivative · entry 2

SCOTT JULIE A · CIK 0001234619 · 10% owner

Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002 · CIK 0001908851 · 10% owner

IXL Ltd Liability Co · CIK 0001909090 · 10% owner

Juliana Sarah Scott Rose Trust · CIK 0001909078 · 10% owner

Elizabeth Lauren Scott Rose Trust · CIK 0001908961 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 655,289

F2 · balance_after: Composed of 230,956 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 43,903 shares held of record by Holland Elizabeth Scott Trust, 43,903 shares held of record by Harper Grace Scott Trust, 43,904 shares held of record by Harrison William Scott Trust, 41,473 shares held of record by Juliana Sarah Scott Rose Trust, 41,472 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.

F2 · ownership.nature: Composed of 230,956 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 43,903 shares held of record by Holland Elizabeth Scott Trust, 43,903 shares held of record by Harper Grace Scott Trust, 43,904 shares held of record by Harrison William Scott Trust, 41,473 shares held of record by Juliana Sarah Scott Rose Trust, 41,472 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.

F3 · ownership.nature: 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.

SEC source: 0001493152-24-044332 · ownership.xml · nonDerivative · entry 1

SCOTT JULIE A · CIK 0001234619 · 10% owner

Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002 · CIK 0001908851 · 10% owner

IXL Ltd Liability Co · CIK 0001909090 · 10% owner

Juliana Sarah Scott Rose Trust · CIK 0001909078 · 10% owner

Elizabeth Lauren Scott Rose Trust · CIK 0001908961 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 670,439

F1 · balance_after: Composed of 233,986 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 43,903 shares held of record by Holland Elizabeth Scott Trust, 43,903 shares held of record by Harper Grace Scott Trust, 43,904 shares held of record by Harrison William Scott Trust, 47,533 shares held of record by Juliana Sarah Scott Rose Trust, 47,532 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.

F1 · ownership.nature: Composed of 233,986 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 43,903 shares held of record by Holland Elizabeth Scott Trust, 43,903 shares held of record by Harper Grace Scott Trust, 43,904 shares held of record by Harrison William Scott Trust, 47,533 shares held of record by Juliana Sarah Scott Rose Trust, 47,532 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.

F3 · ownership.nature: 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.

SEC source: 0000860413-24-000134 · wk-form4_1730840459.xml · nonDerivative · entry 1

Reuter James A · CIK 0002042435 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,974

F1 · shares: Shares issuable upon vesting of restricted stock units granted to the reporting person in connection with his appointment as CEO and director of the issuer pursuant to the issuer's 2023 Equity and Incentive Plan. The restricted stock units vest on November 1, 2029 subject to the reporting person's continued employment through the vesting date.

SEC source: 0001493152-25-006670 · ownership.xml · nonDerivative · entry 1

Scott Risa Kae · CIK 0001798829 · 10% owner

Risa K Scott TTEE Risa K Scott Trust Dtd 12/4/15 · CIK 0001908674 · 10% owner

Risa K. Scott & John Heyneman Jr., TTEEs FBO Risa K Scott Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908770 · 10% owner

Risa K Scott Grantor Retained Annuity Trust Dtd 5/19/24 · CIK 0002056408 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnote

Disclosed balance after: 322,546

F1 · ownership.nature: 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 Risa K Scott.

F2 · ownership.nature: Composed of 322,546 shares held of record by Risa K. Scott TTEE, Risa K Scott Trust dtd 12/4/15, over which Risa K Scott has sole voting & dispositive power.

SEC source: 0000860413-24-000122 · wk-form4_1724792190.xml · nonDerivative · entry 1

HEYNEMAN JOHN M JR · CIK 0001198518 · Director · 10% owner

Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908849 · 10% owner

Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust · CIK 0001908784 · 10% owner

Towanda Investments Limited Partnership · CIK 0001908810 · 10% owner

John M Heyneman Jr. Trust · CIK 0001908848 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · see footnote

Disclosed balance after: 1,415,151

F1 · ownership.nature: 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.

F2 · ownership.nature: 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; 4552 shares held of record by John Heyneman, Jr.'s spouse; 1095 shares held of record by John Heyneman, Jr.'s daughter; 1,465 shares held of record by John Heyneman, Jr.'s son Quinn; and 575 shares held of record by John Heyneman, Jr.'s son Bae-John.

SEC source: 0000860413-24-000120 · wk-form4_1722624402.xml · nonDerivative · entry 17

RILEY KEVIN P · CIK 0001408733 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Indirect · As Custodian under UTMA - 6

Disclosed balance after: 523

SEC source: 0000860413-24-000120 · wk-form4_1722624402.xml · nonDerivative · entry 16

RILEY KEVIN P · CIK 0001408733 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Indirect · As Custodian under UTMA - 5

Disclosed balance after: 811

SEC source: 0000860413-24-000120 · wk-form4_1722624402.xml · nonDerivative · entry 15

RILEY KEVIN P · CIK 0001408733 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Indirect · As Custodian under UTMA - 4

Disclosed balance after: 1,118

SEC source: 0000860413-24-000120 · wk-form4_1722624402.xml · nonDerivative · entry 14

RILEY KEVIN P · CIK 0001408733 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Indirect · As Custodian under UTMA -3

Disclosed balance after: 1,436

SEC source: 0000860413-24-000120 · wk-form4_1722624402.xml · nonDerivative · entry 13

RILEY KEVIN P · CIK 0001408733 · Director · President & CEO

10b5-1 filing: No plan indicated

Ownership: Indirect · As Custodian under UTMA -2

Disclosed balance after: 1,436

F2 · price: The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $29.88 to $29.90. 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.