X0508 4 2024-01-16 0 0000909832 COSTCO WHOLESALE CORP /NEW COST 0001928633 Frates Caton 999 LAKE DRIVE ISSAQUAH WA 98027 0 1 0 0 Executive Vice President 0 Common Stock 2024-01-16 4 S 0 740 683.4991 D 6720.559 D The price shown is a weighted average price for shares purchased in multiple transactions; the purchase prices ranged from $683.49 to $683.525 per share. The reporting person will provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, information regarding the number of shares purchased at each price within the range. /s/ Alejandro Torres, Attorney-in-Fact 2024-01-16