Monolithic Power Systems (MPWR)

=== SEC Form 4 — Statement of Changes in Beneficial Ownership === Document Type: 4 Period of Report: 2026-08-24 10b5-1 Pre-arranged Plan: No --- Issuer --- Name: MONOLITHIC POWER SYSTEMS, INC. (MPWR) CIK: 0001280452 --- Reporting Owner --- Name: DEAN ROBERT W II CIK: 0001445300 Role: Officer (Interim CFO) --- Non-Derivative Transactions --- [Transaction #1] Security: Common Stock Date: 2026-08-24 | Code: S (Open market sale) Shares: -32 | Price: $1,297.72 Total Value: $41,527.04 Shares Owned After: 7,094 | Ownership: D (Direct) Footnotes: [F1] The reported sale was to cover tax withholding obligations upon the vesting of restricted stock units. [F2] 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. [Transaction #2] Security: Common Stock Date: 2026-08-24 | Code: J (Other acquisition/disposition) Shares: -5 | Price: $0.00 Shares Owned After: 7,089 | Ownership: D (Direct) Footnotes: [F3] 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. --- Holdings --- [Holding #1] Security: Common Stock Ownership: I (Indirect) --- Footnotes (Complete Index) --- F1: The reported sale was to cover tax withholding obligations upon the vesting of restricted stock units. F2: 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. F3: 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. --- Signature --- /s/ /s/ Saria Tseng, attorney-in-fact for Mr. Robert W. Dean II (2026-08-26)