Form 4 Filing for Luis Machuca

This filing details a transaction by Luis Machuca, a director at Columbia Banking System, Inc. On June 15, 2026, Machuca acquired 563 shares of Deferred Compensation Phantom Stock at a price of $31.78 per share. This acquisition was made under the company's deferred compensation plan and will be settled after Machuca ceases his role as a director. Following this transaction, Machuca holds 48,966 shares of this phantom stock. The underlying security for this transaction is Common stock. The filing was signed by Andrea M. Newburn, acting as attorney-in-fact for Machuca.