| Name | Relationship | Address | Signature | Signature date | CIK |
|---|---|---|---|---|---|
| Nixon Torran B | Senior Executive VP | C/O COLUMBIA BANKING SYSTEM, INC., 1301 A STREET, TACOMA | /s/ Andrea M. Newburn, Attorney-in-fact | 02 Mar 2026 | 0001689701 |
| Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Ownership | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| transaction | COLB | Common Stock | Tax liability | $84,781 | -2,980 | -2.8% | $28.45 | 102,710 | 01 Mar 2026 | Direct | |
| holding | COLB | Common Stock | 3,650 | 01 Mar 2026 | by family trust | ||||||
| holding | COLB | Common Stock | 1,876 | 01 Mar 2026 | by 401(k) |