| Name | Relationship | Address | Signature | Signature date | CIK |
|---|---|---|---|---|---|
| Namdar Frank | EVP Chief Credit Officer | C/O COLUMBIA BANKING SYSTEM, INC., 1301 A STREET, TACOMA | /s/ Andrea M. Newburn, Attorney-in-fact | 02 Mar 2026 | 0001759802 |
| Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Ownership | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| transaction | COLB | Common Stock | Tax liability | $51,438 | -1,808 | -5.6% | $28.45 | 30,470 | 01 Mar 2026 | Direct | |
| holding | COLB | Common Stock | 4,146 | 01 Mar 2026 | by 401(k) |