Monolithic Power Systems CEO Michael Hsing Files Form 144 for $40.3M Sale

Executive Summary

On September 28, 2026, Michael Hsing, CEO and Director of Monolithic Power Systems, Inc. ($MPWR), filed Form 144 providing notice of intent to sell 30,000 shares of common stock with an estimated aggregate market value of $40,349,049.00.

Key Transaction Details

• Filer: Michael Hsing (Officer & Director)
• Number of Shares: 30,000 common shares
• Estimated Aggregate Value: $40,349,049.00 (~$1,344.97 per share)
• Shares Outstanding: 49,143,000 (proposed sale represents approximately 0.06% of total shares outstanding)
• Acquisition Sources: 29,961 shares acquired via Performance Shares (vested between June 30, 2023, and February 7, 2025) and 39 shares acquired through the Employee Stock Purchase Plan (between February 15, 2023, and February 17, 2025)
• Broker: Morgan Stanley Smith Barney LLC Executive Financial Services

Governance & Plan Context

• The proposed sale is executed pursuant to a pre-arranged Rule 10b5-1 trading plan adopted on May 29, 2026, satisfying the standard cooling-off period requirements.
• The filer reported no other securities sold during the preceding three months.