X0508 4 2026-01-02 0001280452 MONOLITHIC POWER SYSTEMS INC MPWR 0001415033 BLEGEN THEODORE 1555 PALM BEACH LAKES BLVD. WEST PALM BEACH FL 33401 false true false false EVP and CFO 1 Common Stock 2026-01-02 4 S false 80 927.61 D 71252 D Common Stock 2026-01-02 4 S false 194 930.86 D 71058 D Common Stock 2026-01-02 4 S false 80 933.64 D 70978 D Common Stock 2026-01-02 4 S false 40 934.74 D 70938 D Common Stock 2026-01-02 4 S false 80 935.33 D 70858 D Common Stock 2026-01-02 4 S false 120 936.50 D 70738 D Common Stock 2026-01-02 4 S false 460 938.52 D 70278 D Common Stock 2026-01-02 4 S false 117 939.75 D 70161 D Common Stock 2026-01-02 4 S false 40 940.03 D 70121 D Common Stock 2026-01-02 4 S false 406 941.60 D 69715 D Common Stock 2026-01-02 4 S false 74 942.42 D 69641 D Common Stock 2026-01-02 4 S false 539 943.71 D 69102 D Common Stock 2026-01-02 4 S false 650 944.35 D 68452 D Common Stock 2026-01-02 4 S false 40 945.00 D 68412 D Common Stock 2026-01-02 4 S false 80 946.62 D 68332 D Common Stock 5331 I Irrevocable Trust FBO Sarah N. Blegen Common Stock 5331 I Irrevocable Trust FBO Theodore F. Blegen These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 2/26/2025. 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 $935.08 to $935.57. 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 $938.14 to $938.69. 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 $939.51 to $939.99. 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 $941.00 to $941.67. 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 $942.01 to $942.77. 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 $943.37 to $943.85. 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 $944.01 to $944.51. 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, attorney-in-fact for Mr. Bernie Blegen 2026-01-02