X0508 4 2025-11-19 0001280452 MONOLITHIC POWER SYSTEMS INC MPWR 0001360833 Sciammas Maurice 1555 PALM BEACH LAKES BLVD. WEST PALM BEACH WA 33401 false true false false EVP, WW Sales & Marketing 0 Common Stock 2025-11-19 4 S false 431.00 875.26 D 175841 D Common Stock 2025-11-19 4 S false 940.00 876.62 D 174901 D Common Stock 2025-11-19 4 S false 1976.00 877.45 D 172925 D Common Stock 2025-11-19 4 S false 1854.00 878.55 D 171071 D Common Stock 2025-11-19 4 S false 1966.00 879.54 D 169105 D Common Stock 2025-11-19 4 S false 3776.00 880.58 D 165329 D Common Stock 2025-11-19 4 S false 2469.00 881.42 D 162860 D Common Stock 2025-11-19 4 S false 3344.00 882.51 D 159516 D Common Stock 2025-11-19 4 S false 6513.00 883.50 D 153003 D Common Stock 2025-11-19 4 S false 2149.00 884.44 D 150854 D Common Stock 2025-11-19 4 S false 1738.00 885.10 D 149116 D Common Stock 2025-11-19 4 S false 810.00 886.01 D 148306 D Common Stock 1699 I The Joseph Roger Sciammas 2020 Irrevocable Trust Common Stock 2000 I Rosalind Sciammas Family 2021 Trust Common Stock 1299 I Rosalind Sciammas Brokerage Account Common Stock 49460 I Sciammas Family Trust Common Stock 26660 I Various Sciammas GRATs Common Stock 1699 I The Patrick Francis Sciammas 2020 Irrevocable Trust Common Stock 4015 I By Sciammas Trust 2020 Common Stock 5000 I Clement Sciammas Family 2021 Trust Common Stock 1000 I Peter Rafferty and Eric Toothill 2021Trust Common Stock 1699 I The Chloe Liliane Sciammas 2020 Irrevocable Trust Common Stock 1499 I Clement Sciammas Trust 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 $875.01 to $875.95. 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 $876.28 to $876.97. 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 $877.00 to $877.97. 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 $878.00 to $878.97. 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 $879.25 to $879.99. 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 $880.07 to $880.94. 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 $881.01 to $881.93. 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 $882.06 to $882.92. 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 $883.00 to $883.93. 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 $884.00 to $884.69. 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 $885.00 to $885.99. 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 $886.00 to $886.15. 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. Maurice Sciammas 2025-11-19