144 0001928633 XXXXXXXX LIVE 0000909832 Costco Wholesale Corporation 000-20355 999 Lake Drive Issaquah WA 98027 4253138100 Caton Frates Officer Common Merrill Lynch

1800 K ST NW Suite 800 Washington DC 20006

700 689758 443652540 04/01/2026 NASDAQ Common 10/03/2025 Stock Plan Activity Issuer N 700 10/03/2025 n/a Y 04/01/2026 Caton Frates