MPWR insider tax withholding: 54,543 shares at $1,096.63

Monolithic Power Systems (MPWR): Form 4 insider transaction EVP & General Counsel Saria Tseng reported a Code F transaction on 10/30/2025, reflecting tax withholding related to the vesting of market-based RSUs granted in October 2022.

Rhea-AI Filing Summary

Monolithic Power Systems (MPWR): Form 4 insider transaction

EVP & General Counsel Saria Tseng reported a Code F transaction on 10/30/2025, reflecting tax withholding related to the vesting of market-based RSUs granted in October 2022. The company withheld 54,543 shares of common stock at a price of $1,096.63 per share to satisfy income tax obligations.

Following this withholding, the reporting person directly beneficially owns 207,331 shares of MPWR common stock. Code F indicates shares were disposed of by the issuer solely to cover taxes upon award vesting.

Insider Trade Summary

Exercise Price or Tax Liability: 54,543 shares

Exercise Price or Tax Liability 1 txn

Insider Tseng Saria

Role EVP & General Counsel

Type	Security	Shares	Price	Value
Exercise Price or Tax Liability	Common Stock	54,543	$1,096.63	$59.81M

Holdings After Transaction: Common Stock — 207,331 shares (Direct)

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 disclose in this Form 4?

The EVP & General Counsel reported a Code F transaction for tax withholding on 10/30/2025 tied to vesting of market-based RSUs from October 2022.

How many MPWR shares were withheld for taxes?

54,543 shares of common stock were withheld by the company to satisfy income tax obligations.

At what price were the shares recorded for withholding?

The reported price was $1,096.63 per share.

What is the reporting person’s role at MPWR?

EVP & General Counsel.

How many MPWR shares does the insider own after the transaction?

Direct beneficial ownership is 207,331 shares following the reported transaction.

What does Transaction Code F mean on Form 4?

Code F indicates shares were disposed to cover tax withholding arising from equity award vesting.

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

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Accepted by SEC EDGAR 10/31/2025 - 04:44 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^*

Tseng Saria

(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 & General Counsel

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		54,543(1)	D	$1,096.63	207,331	D

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	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.