Theodore Blegen - 02 Jan 2026 Form 4 Insider Report for MONOLITHIC POWER SYSTEMS INC (MPWR)

Role
EVP and CFO
Signature
/s/ Saria Tseng, attorney-in-fact for Mr. Bernie Blegen
Issuer symbol
MPWR
Transactions as of
02 Jan 2026
Net transactions value
-$2,821,399
Form type
4
Filing time
06 Jan 2026, 16:33:18 UTC
Previous filing
02 Dec 2025
Next filing
04 Feb 2026
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
BLEGEN THEODORE EVP and CFO 1555 PALM BEACH LAKES BLVD., WEST PALM BEACH /s/ Saria Tseng, attorney-in-fact for Mr. Bernie Blegen 02 Jan 2026 0001415033

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction MPWR Common Stock Sale $74,209 -80 -0.11% $927.61 71,252 02 Jan 2026 Direct F1
transaction MPWR Common Stock Sale $180,587 -194 -0.27% $930.86 71,058 02 Jan 2026 Direct F1
transaction MPWR Common Stock Sale $74,691 -80 -0.11% $933.64 70,978 02 Jan 2026 Direct F1
transaction MPWR Common Stock Sale $37,390 -40 -0.06% $934.74 70,938 02 Jan 2026 Direct F1
transaction MPWR Common Stock Sale $74,826 -80 -0.11% $935.33 70,858 02 Jan 2026 Direct F1, F2
transaction MPWR Common Stock Sale $112,380 -120 -0.17% $936.50 70,738 02 Jan 2026 Direct F1
transaction MPWR Common Stock Sale $431,719 -460 -0.65% $938.52 70,278 02 Jan 2026 Direct F1, F3
transaction MPWR Common Stock Sale $109,951 -117 -0.17% $939.75 70,161 02 Jan 2026 Direct F1, F4
transaction MPWR Common Stock Sale $37,601 -40 -0.06% $940.03 70,121 02 Jan 2026 Direct F1
transaction MPWR Common Stock Sale $382,290 -406 -0.58% $941.60 69,715 02 Jan 2026 Direct F1, F5
transaction MPWR Common Stock Sale $69,739 -74 -0.11% $942.42 69,641 02 Jan 2026 Direct F1, F6
transaction MPWR Common Stock Sale $508,660 -539 -0.77% $943.71 69,102 02 Jan 2026 Direct F1, F7
transaction MPWR Common Stock Sale $613,828 -650 -0.94% $944.35 68,452 02 Jan 2026 Direct F1, F8
transaction MPWR Common Stock Sale $37,800 -40 -0.06% $945.00 68,412 02 Jan 2026 Direct F1
transaction MPWR Common Stock Sale $75,730 -80 -0.12% $946.62 68,332 02 Jan 2026 Direct F1
holding MPWR Common Stock 5,331 02 Jan 2026 Irrevocable Trust FBO Sarah N. Blegen
holding MPWR Common Stock 5,331 02 Jan 2026 Irrevocable Trust FBO Theodore F. Blegen
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

Transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Explanation of Responses:

Id Content
F1 These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 2/26/2025.
F2 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.
F3 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.
F4 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.
F5 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.
F6 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.
F7 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.
F8 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.