[Form 4] MONOLITHIC POWER SYSTEMS INC Insider Trading Activity

Monolithic Power Systems (MPWR) disclosed an insider equity award.

Rhea-AI Filing Summary

Monolithic Power Systems (MPWR) disclosed an insider equity award. On October 25, 2025, EVP & General Counsel acquired 135,520 common shares at $0 upon certification of performance criteria for previously granted market-based RSUs (MSUs). The MSUs were granted on October 25, 2022 and tied to five stock price targets and relative TSR over a three-year period. All awarded shares fully vested on October 25, 2025.

Following the transaction, the reporting person beneficially owned 261,874 shares, held directly.

Insider Trade Summary

Grant/Award: 135,520 shares

Grant/Award 1 txn

Insider Tseng Saria

Role EVP & General Counsel

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	135,520	$0.00	$0.00

Holdings After Transaction: Common Stock — 261,874 shares (Direct)

Footnotes (1)

1. F1. On October 25, 2022, the reporting person was granted market-based restricted stock units ("MSUs") subject to the achievement of five stock price targets and relative total stockholder return percentile rank over a three-year performance and vesting period. On October 25, 2025, the Company's Compensation Committee of the Board of Directors certified and approved the achievement of the performance criteria for the MSUs, which resulted in 135,520 shares being awarded to the reporting person. All of the shares fully vested on October 25, 2025, pursuant to the grant agreement.

FAQ

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

What did MPWR report on this Form 4?

An insider equity award where the EVP & General Counsel acquired 135,520 common shares at $0 due to MSU performance certification.

Who is the reporting person in MPWR's Form 4?

The reporting person is MPWR’s EVP & General Counsel.

When did the MPWR MSUs vest and get certified?

Performance was certified and all awarded shares fully vested on October 25, 2025.

How many MPWR shares were acquired in this transaction?

135,520 common shares were acquired upon MSU vesting.

What is the reporting person’s MPWR share ownership after the transaction?

Beneficial ownership is 261,874 shares, held directly.

What were the terms of the MPWR MSUs?

Granted on October 25, 2022, the MSUs were subject to five stock price targets and relative total stockholder return over three years.

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

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Accepted by SEC EDGAR 10/28/2025 - 09:38 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)
10/25/2025

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	10/25/2025		A		135,520(1)	A	$0	261,874	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. On October 25, 2022, the reporting person was granted market-based restricted stock units ("MSUs") subject to the achievement of five stock price targets and relative total stockholder return percentile rank over a three-year performance and vesting period. On October 25, 2025, the Company's Compensation Committee of the Board of Directors certified and approved the achievement of the performance criteria for the MSUs, which resulted in 135,520 shares being awarded to the reporting person. All of the shares fully vested on October 25, 2025, pursuant to the grant agreement.

Remarks:

	/s/ Saria Tseng	10/27/2025
	** 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.