MPWR CFO withholds 48,298 shares for taxes at $1,096.63 each in Form 4

Monolithic Power Systems (MPWR) EVP and CFO Bernie Blegen reported a Form 4 transaction.

Rhea-AI Filing Summary

Monolithic Power Systems (MPWR) EVP and CFO Bernie Blegen reported a Form 4 transaction. On 10/30/2025, 48,298 shares of common stock were withheld at $1,096.63 per share to satisfy income taxes related to the earnout and vesting of market-based RSUs granted in October 2022.

Following the transaction, Blegen directly owned 77,332 shares. Indirect holdings include 5,331 shares in an irrevocable trust for Sarah N. Blegen and 5,331 shares in an irrevocable trust for Theodore F. Blegen.

Insider Trade Summary

Exercise Price or Tax Liability: 48,298 shares

Exercise Price or Tax Liability 3 txns

Insider BLEGEN THEODORE

Role EVP and CFO

Type	Security	Shares	Price	Value
Exercise Price or Tax Liability	Common Stock	48,298	$1,096.63	$52.97M
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 77,332 shares (Direct); Common Stock — 5,331 shares (Indirect, Irrevocable Trust FBO Sarah N. Blegen); Common Stock — 5,331 shares (Indirect, Irrevocable Trust FBO Theodore F. Blegen)

Footnotes (1)

1. F1. The sales transaction reported in this Form 4 represents shares of common stock withheld by the Company to satisfy the income tax obligations in connection with the earnout and vesting of the market-based restricted stock units granted in October 2022, previously reported in a Form 4.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did MPWR's CFO report on Form 4?

Bernie Blegen reported a tax-withholding transaction involving 48,298 shares related to the vesting of market-based RSUs granted in October 2022.

What was the transaction price per share?

The shares were withheld at $1,096.63 per share.

When did the MPWR Form 4 transaction occur?

The transaction date was 10/30/2025.

How many MPWR shares does the CFO own directly after the transaction?

He beneficially owns 77,332 shares directly.

Does the CFO report any indirect holdings?

Yes. Indirect holdings include 5,331 shares in a trust for Sarah N. Blegen and 5,331 shares in a trust for Theodore F. Blegen.

What does transaction code F indicate on Form 4 for MPWR?

Code F denotes shares withheld by the company to satisfy income tax obligations upon equity vesting.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 10/31/2025 - 04:45 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a 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). See Instruction 10.

1. Name and Address of Reporting Person^*

BLEGEN THEODORE

(Last) (First) (Middle)

5808 LAKE WASHINGTON BLVD NE

(Street)

KIRKLAND WA 98033

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
MONOLITHIC POWER SYSTEMS INC [ MPWR ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP and CFO

3. Date of Earliest Transaction (Month/Day/Year)
10/30/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/30/2025		F		48,298(1)	D	$1,096.63	77,332	D
Common Stock								5,331	I	Irrevocable Trust FBO Sarah N. Blegen
Common Stock								5,331	I	Irrevocable Trust FBO Theodore F. Blegen

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The sales transaction reported in this Form 4 represents shares of common stock withheld by the Company to satisfy the income tax obligations in connection with the earnout and vesting of the market-based restricted stock units granted in October 2022, previously reported in a Form 4.

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Bernie Blegen	10/30/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.