[Form 4] MONOLITHIC POWER SYSTEMS INC Insider Trading Activity

Rhea-AI Filing Summary

Monolithic Power Systems (MPWR) reported an insider transaction by its EVP & General Counsel. On 10/24/2025, the reporting person sold 1,300 shares of common stock at a price of $1,087.62 per share under transaction code “S.” Following the sale, the filer beneficially owned 126,354 shares, held directly. The filing notes the trade was made pursuant to a Rule 10b5-1 trading plan adopted on 8/30/2024.

Insights

Equity markets analyst

Routine insider sale under a pre-set 10b5-1 plan; neutral.

The EVP & General Counsel executed a sale of 1,300 MPWR common shares at $1,087.62 on 10/24/2025. The filing states the sale was made pursuant to a Rule 10b5-1 plan adopted on 8/30/2024, indicating a pre-arranged trading schedule.

Post-transaction holdings are 126,354 shares, reported as directly owned. Such planned sales are administrative and do not by themselves indicate changes in company outlook.

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).

X

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)
10/24/2025

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	10/24/2025		S		1,300(1)	D	$1,087.62	126,354	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. This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 8/30/2024.

Remarks:

	/s/ Saria Tseng	10/24/2025
	** 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.

FAQ

What insider transaction did MPWR report?

An EVP & General Counsel sold 1,300 shares of common stock at $1,087.62 on 10/24/2025.

How many MPWR shares does the filer hold after the sale?

The filer beneficially owned 126,354 shares following the reported transaction.

Was the MPWR insider trade under a Rule 10b5-1 plan?

Yes. The sale was made pursuant to a Rule 10b5-1 trading plan adopted on 8/30/2024.

What role does the reporting person hold at MPWR?

The reporting person is an Officer, serving as EVP & General Counsel.

What was the ownership form for the MPWR shares sold?

The transaction and remaining holdings were reported as Direct (D) ownership.

What was the transaction code used in the filing?

The filing lists transaction code S, indicating an open market or private sale of non-derivative securities.