X0306 4 2020-12-11 0 0000909832 COSTCO WHOLESALE CORP /NEW COST 0000904858 STANTON JOHN W 999 LAKE DRIVE ISSAQUAH WA 98027 1 0 0 0 Common Stock 2020-12-11 4 A 0 34 A 21867 D Common Stock 422 I Stanton Family Trust Represents additional restricted stock units ("RSUs") resulting from the upward adjustment of outstanding unvested RSUs by a factor of 1.019, in connection with the special cash dividend payable by the issuer on December 11, 2020. The adjustment was required under applicable plan documents. The additional RSUs reported are subject to the same vesting schedules as the original unvested RSUs to which they relate. Not applicable. Grant of Restricted Stock Units. Deanna K. Nakashima, attorney-in-fact 2020-12-11