X0609 4 2026-08-24 0001280452 MONOLITHIC POWER SYSTEMS, INC. MPWR 0001445300 DEAN ROBERT W II false 1555 PALM BEACH LAKES BLVD. WEST PALM BEACH FL 33401 false true false false Interim CFO 0 Common Stock 2026-08-24 4 S false 32 1297.72 D 7094 D Common Stock 2026-08-24 4 J false 5 0 D 7089 D Common Stock 65 I Held by Parent & Daughter The reported sale was to cover tax withholding obligations upon the vesting of restricted stock units. The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,296.07 to $1,298.01. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price. The reported transaction involved a transfer of securities from the reporting person's direct holdings to an individual who is not an immediate family member sharing the same household. No funds were exchanged and no sale of shares occurred in the transfer. Following the completion of the transfer, the reporting person no longer retains any pecuniary interest in the shares. /s/ Saria Tseng, attorney-in-fact for Mr. Robert W. Dean II 2026-08-26