X0609 4 2026-10-22 0 0000909832 COSTCO WHOLESALE CORP /NEW COST 0001771770 MILLERCHIP GARY false 999 LAKE DRIVE ISSAQUAH WA 98027 0 1 0 0 Executive Vice President 0 Common Stock 2026-10-22 4 A 0 6140 0 A 21605.301 D Common Stock 2026-10-22 4 F 0 313.451 1018.21 D 21291.85 D Common Stock 2026-10-22 4 F 0 500.323 1018.21 D 20791.527 D Common Stock 2026-10-22 4 F 0 816.968 1018.21 D 19974.559 D Grant was initially made on October 22, 2025, subject to performance conditions concerning fiscal 2026, which have been deemed satisfied by the Compensation Committee of the Board of Directors. The earned awards vest one-third on the first anniversary of the grant date and an additional one-third vest over each of the ensuing two years based on continued employment with the Company. Not applicable. Grant of Restricted Stock Units. This transaction is a withholding by the Company for taxes in connection with the vesting of previously granted restricted stock units. The price represents the closing market price of Costco common stock on Nasdaq on October 22, 2026. Alejandro Torres, Attorney-in-Fact 2026-10-26