$COST · Costco Wholesale Corporation

This Form 4 filing reports changes in beneficial ownership for Adam Webb Self, an Executive Vice President of Costco Wholesale Corporation. The transactions occurred on October 22, 2026, and involved the disposition of Costco common stock.

The reported transactions were not open-market sales. Instead, they were withholdings of shares by the company to cover taxes required in connection with the vesting of previously granted restricted stock units. The shares were valued at $1,018.21 each, which was the closing market price of Costco common stock on Nasdaq on the transaction date. Across the reported lines, a total of 259.767 shares were disposed of in these tax withholding transactions.

Following these transactions, the reporting person directly held 3,269.585 shares of Costco common stock.