X0306 4 2019-10-22 0001280452 MONOLITHIC POWER SYSTEMS INC MPWR 0001415033 Blegen Theodore 4040 LAKE WASHINGTON BLVD. NE, SUITE 201 KIRKLAND WA 98033 1 CFO Common Stock 2019-10-22 4 M 0 9600 0 A 102867 D Restricted Stock Units 2019-10-22 4 M 0 9600 0 D Common Stock 9600 19200 D On October 25, 2018, the reporting person was granted a target number of 9,600 performance units and can earn up to a maximum of 48,000 performance units subject to satisfaction of five stock price targets ranging from $140 to $172 over the performance periods from October 25, 2018 to December 31, 2023, as determined by the Compensation Committee of the Company. All performance units are subject to time based vesting and require service through January 1, 2024 or an earlier change in control. Once vested, performance units convert into shares of common stock on a 1-for-1 basis and one-third of the resulting shares have no sales restrictions and are sellable on January 1, 2024, one-third of the shares have sales restrictions until January 1, 2025 and one-third have sales restrictions until January 1, 2026. On October 22,2019, the third price target had been met and approved by the Compensation Committee, which resulted in 9,600 units being credited, subject to time based vesting above. /s/ By: Saria Tseng For: T. Bernie Blegen 2019-10-24