144 0001192171 XXXXXXXX LIVE 0001280452 MONOLITHIC POWER SYSTEMS INC 000-51026 1555 Palm Beach Lakes Blvd West Palm Beach FL 33401 4252969956 Kuo Wei Chang Director Common UBS Financial Services Inc

1000 Harbor Blvd 3rd Floor Weehawken NJ 07086

100 142000 49130000 08/11/2026 NASDAQ Common 02/06/2025 RSU Issuer N 91 02/06/2025 Not Applicable Common 02/04/2026 RSU Issuer N 9 02/04/2026 Not Applicable Y 08/11/2026 /s/Mijo Suric, for UBS Financial Services Inc, as attorney-in-fact for Kuo Wei Chang