X0508 4 2024-10-15 0000909832 COSTCO WHOLESALE CORP /NEW COST 0001916969 Riel Pierre 999 LAKE DRIVE ISSAQUAH WA 98027 1 Executive Vice President 0 Common Stock 2024-10-15 4 S 0 2000 896.713 D 10210.246 D The price shown is a weighted average price for shares sold in multiple transactions; the sale prices ranged from $896.611 to $896.87 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 sold at each price within the range. /s/ Alejandro Torres, Attorney-in-Fact 2024-10-15