X0609 4 2026-04-08 0001280452 MONOLITHIC POWER SYSTEMS INC MPWR 0001312593 Tseng Saria false 1555 PALM BEACH LAKES BLVD. WEST PALM BEACH FL 33401 false true false false EVP & General Counsel 1 Common Stock 2026-04-08 4 S false 560 1266.48 D 165386 D Common Stock 2026-04-08 4 S false 360 1270.29 D 165026 D Common Stock 2026-04-08 4 S false 240 1279.55 D 164786 D Common Stock 2026-04-08 4 S false 120 1287.12 D 164666 D Common Stock 2026-04-08 4 S false 400 1292.08 D 164266 D Common Stock 2026-04-08 4 S false 800 1302.52 D 163466 D Common Stock 2026-04-08 4 S false 1279 1308.30 D 162187 D Common Stock 2026-04-08 4 S false 4244 1312.82 D 157943 D Common Stock 2026-04-08 4 S false 840 1319.25 D 157103 D Common Stock 2026-04-08 4 S false 120 1321.94 D 156983 D Common Stock 1000 I C&T Discovery Foundation These transactions were made pursuant to a Rule 10b5-1 trading plan adopted on 11/28/2025. 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 $1,264.04 to $1,268.56. 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 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 $1,269.36 to $1,272.23. 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 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 $1,277.78 to $1,281.49. 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 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 $1,284.26 to $1,289.24. 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 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 $1,290.95 to $1,294.78. 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 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 $1,299.99 to $1,304.82. 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 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 $1,305.08 to $1,310.00. 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 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 $1,310.27 to $1,315.08. 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 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 $1,316.25 to $1,321.04. 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 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 $1,321.50 to $1,322.56. 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. /s/ Saria Tseng 2026-04-10