MPWR (NASDAQ: MPWR) EVP logs small 30-share sale under 10b5-1 plan

Rhea-AI Filing Summary

Monolithic Power Systems EVP Maurice Sciammas reported an open-market sale of 30 shares of common stock on March 20, 2026. The sale was executed indirectly through the Clement Sciammas Trust at a weighted average price of $1,095.07 per share, with individual prices ranging from $1,094.79 to $1,095.19. Following the sale, the trust held 1,269 shares, while Sciammas also reported 178,644 shares held directly and additional indirect holdings through various family trusts and accounts. The transaction was carried out under a Rule 10b5-1 trading plan adopted on November 19, 2025.

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^*

Sciammas Maurice

(Last) (First) (Middle)

1555 PALM BEACH LAKES BLVD.

(Street)

WEST PALM BEACH FLORIDA 33401

(City) (State) (Zip)

UNITED STATES

(Country)

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, WW Sales & Marketing

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/20/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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								178,644(1)	D
Common Stock	03/20/2026		S		30(2)	D	$1,095.07(3)	1,269	I	Clement Sciammas Trust
Common Stock								1,699	I	The Joseph Roger Sciammas 2020 Irrevocable Trust
Common Stock								2,000	I	Rosalind Sciammas Family 2021 Trust
Common Stock								1,299	I	Rosalind Sciammas Brokerage Account
Common Stock								26,660	I	Various Sciammas GRATs
Common Stock								1,699	I	The Patrick Francis Sciammas 2020 Irrevocable Trust
Common Stock								4,015	I	By Sciammas Trust 2020
Common Stock								1,000	I	Peter Rafferty and Eric Toothill 2021Trust
Common Stock								1,699	I	The Chloe Liliane Sciammas 2020 Irrevocable Trust
Common Stock								5,000	I	Clement Sciammas Family 2021 Trust
Common Stock								49,460	I	Sciammas Family 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. Ending balance includes 19 shares acquired on February 17, 2026 through the Company's qualified ESPP program.

2. These transactions were made pursuant to a Rule 10b5-1 trading plan adopted on 11/19/2025.

3. The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,094.79 to $1,095.19. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Maurice Sciammas	03/24/2026
	** 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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did MPWR executive Maurice Sciammas report on March 20, 2026?

Maurice Sciammas reported an open-market sale of 30 shares of Monolithic Power Systems common stock. The sale was executed indirectly through the Clement Sciammas Trust on March 20, 2026, and reflects a small portion of his overall reported direct and indirect holdings.

At what price were the MPWR shares sold in Maurice Sciammas’s March 2026 Form 4?

The 30 MPWR shares were sold at a weighted average price of $1,095.07 per share. Individual sale prices ranged from $1,094.79 to $1,095.19, according to the footnote, with the insider offering to provide full price breakdowns upon request.

How many Monolithic Power Systems (MPWR) shares does Maurice Sciammas hold after this Form 4 transaction?

After the reported sale, the Clement Sciammas Trust held 1,269 MPWR shares, and Sciammas held 178,644 shares directly. The filing also lists additional indirect holdings through multiple family trusts and accounts, indicating substantially larger overall ownership than the 30 shares sold.

Was the March 20, 2026 MPWR insider sale by Maurice Sciammas part of a Rule 10b5-1 plan?

Yes. The filing states these transactions were made under a Rule 10b5-1 trading plan adopted on November 19, 2025. Such pre-arranged plans allow executives to schedule trades in advance, helping separate routine portfolio management from discretionary timing decisions.

How is the March 2026 MPWR insider sale by Maurice Sciammas characterized in the Form 4?

The transaction is coded as an open-market sale of common stock. It involves 30 shares sold indirectly via the Clement Sciammas Trust, with numerous other trust and direct holdings disclosed, suggesting the sale represents only a modest fraction of his reported ownership position.

What indirect ownership structures are disclosed for MPWR shares held by Maurice Sciammas?

The Form 4 lists several indirect holdings, including the Clement Sciammas Trust, various Sciammas GRATs, multiple 2020 irrevocable trusts, family trusts, and a brokerage account. Each entity reports its own post-transaction share balance, reflecting diversified estate and family planning structures.