Monolithic Power (MPWR) insider sales under 10b5-1 plan reported

Rhea-AI Filing Summary

Monolithic Power Systems (MPWR) executive Saria Tseng, EVP & General Counsel, reported open-market sales of common stock under a Rule 10b5-1 plan. On 10/15/2025, she sold 14,028 shares at $1,016.18. On 10/16/2025, she sold 1,499 shares at $1,021.26 and 1,313 shares at $1,030.81. Following these transactions, her beneficial ownership decreased to 127,654 shares. The trading plan was adopted on 8/30/2024.

Insider Trade Summary

Net Seller: 16,840 shares

Net Sell 3 txns

Insider Tseng Saria

Role EVP & General Counsel

Sold 16,840 shs ($17.14M)

Type	Security	Shares	Price	Value
Sale	Common Stock	1,499	$1,021.26	$1.53M
Sale	Common Stock	1,313	$1,030.81	$1.35M
Sale	Common Stock	14,028	$1,016.18	$14.25M

Holdings After Transaction: Common Stock — 127,654 shares (Direct)

Footnotes (1)

1. F1. These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 8/30/2024.

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Form 4 Insider Transactions: What Each Field Means →

Accepted by SEC EDGAR 10/17/2025 - 12:11 PM Learn about SEC filing dates

FAQ

What did MPWR's EVP & General Counsel report on Form 4?

She reported sales of 14,028 shares at $1,016.18 on 10/15/2025, and 1,499 shares at $1,021.26 plus 1,313 shares at $1,030.81 on 10/16/2025.

How many MPWR shares does the reporting person hold after the transactions?

Beneficial ownership is 127,654 shares after the reported sales.

Were these MPWR trades under a Rule 10b5-1 plan?

Yes. The filing states the trades were pursuant to a Rule 10b5-1 plan adopted on 8/30/2024.

Who is the MPWR insider in this Form 4?

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

What were the transaction dates reported for MPWR?

The sales occurred on 10/15/2025 and 10/16/2025.

What was the transaction code used?

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

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)
10/15/2025

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	10/15/2025		S		14,028(1)	D	$1,016.18	130,466	D
Common Stock	10/16/2025		S		1,499(1)	D	$1,021.26	128,967	D
Common Stock	10/16/2025		S		1,313(1)	D	$1,030.81	127,654	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. These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 8/30/2024.

Remarks:

	/s/ Saria Tseng	10/16/2025
	** 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.