144 0001360833 XXXXXXXX LIVE 0001280452 MONOLITHIC POWER SYSTEMS INC 000-51026 1555 PALM BEACH LAKES BLVD. WEST PALM BEACH FL 33401 561-839-3999 Sciammas Maurice Officer Common UBS Financial Services, Inc.

Eleven Madison Avenue 4th Floor New York NY 10010

120 131332.80 49118000 03/20/2026 Nasdaq Common 05/28/2025 Gift Maurice Sciammas Y 05/07/2014 120 05/28/2025 NA N The Sciammas Trust DTD 06/08/2018

1555 PALM BEACH LAKES BLVD WEST PALM BEACH FL 33401

Common 02/10/2026 200 240000.00 Maurice Sciammas

1555 PALM BEACH LAKES BLVD WEST PALM BEACH FL 33401

Common 02/06/2026 1286 1505526.00 Maurice Sciammas

1555 PALM BEACH LAKES BLVD WEST PALM BEACH FL 33401

Common 02/04/2026 21590 25148679.70 The shares covered by this form 144 are being sold under The Sciammas Trust DTD 06/08/2018 03/20/2026 11/19/2025 /s/ UBS Financial Services Inc, as attorney-in-fact for Clement Sciammas