Monolithic Power (MPWR) EVP Deming Xiao sells shares to cover RSU taxes

Rhea-AI Filing Summary

Monolithic Power Systems executive Deming Xiao reported a tax-related stock sale. As EVP, Global Operations, he sold 22,875 shares of common stock on February 6, 2026 at an average price of $1,171.1637 per share.

According to the filing, the sale was made to cover taxes due upon the release of restricted stock units under the company’s equity incentive plan. After this transaction, Xiao directly held 235,932 shares, with additional indirect holdings of 20,455 shares owned by his spouse and 4,336 shares held by the Christopher Chao Xiao Trust.

Insider Trade Summary

Net Seller: 22,875 shares ($26,790,370)

Net Sell 3 txns

Insider Xiao Deming

Role EVP, Global Operations

Sold 22,875 shs ($26.79M)

Type	Security	Shares	Price	Value
Sale	Common Stock	22,875	$1,171.1637	$26.79M
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 235,932 shares (Direct); Common Stock — 20,455 shares (Indirect, by Spouse)

Footnotes (1)

1. [object Object]

Form 4 Insider Transactions: What Each Field Means →

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^*

Xiao Deming

(Last) (First) (Middle)

1555 PALM BEACH LAKES BLVD.

(Street)

WEST PALM BEACH FL 33401

(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, Global Operations

3. Date of Earliest Transaction (Month/Day/Year)
02/06/2026

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	02/06/2026		S		22,875(1)	D	$1,171.1637	235,932	D
Common Stock								20,455	I	by Spouse
Common Stock								4,336	I	Christopher Chao Xiao Trust

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 reported sales were to cover taxes upon the release of restricted stock units, as required by the Company's equity incentive plan.

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Deming Xiao	02/10/2026
	** 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 executive Deming Xiao report?

Deming Xiao reported selling 22,875 shares of Monolithic Power Systems common stock. The shares were sold on February 6, 2026, at an average price of $1,171.1637 per share, primarily to satisfy tax obligations tied to restricted stock unit vesting.

Why did MPWR EVP Deming Xiao sell 22,875 shares of stock?

The filing states the sale was made to cover taxes due upon the release of restricted stock units. This tax-withholding transaction was required by Monolithic Power Systems’ equity incentive plan rather than a discretionary open-market sale for personal liquidity.

How many MPWR shares does Deming Xiao hold after the reported sale?

After the transaction, Deming Xiao directly owned 235,932 shares of Monolithic Power Systems. The filing also shows indirect ownership of 20,455 shares held by his spouse and 4,336 shares held through the Christopher Chao Xiao Trust.

What role does Deming Xiao hold at Monolithic Power Systems (MPWR)?

Deming Xiao serves as Executive Vice President, Global Operations at Monolithic Power Systems. His position makes him a Section 16 reporting insider, requiring prompt disclosure of transactions in MPWR common stock on Form 4 filings with the SEC.

Were the MPWR shares sold by Deming Xiao part of an equity incentive plan?

Yes. The filing explains that the reported stock sales occurred to cover taxes arising from the release of restricted stock units. These restricted stock units were granted under Monolithic Power Systems’ equity incentive plan and vested, triggering tax obligations.

Does the MPWR Form 4 show any indirect holdings for Deming Xiao?

Yes. In addition to his direct holdings, the Form 4 lists 20,455 MPWR shares indirectly owned through his spouse and 4,336 shares indirectly owned through the Christopher Chao Xiao Trust, reflecting broader family-related beneficial ownership positions.