[Form 4] Monolithic Power Systems, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Monolithic Power Systems (MPWR) Form 4 summary: On 08/19/2025 Maurice Sciammas, EVP, Worldwide Sales & Marketing and trustee for multiple family trusts, reported several non‑sale transfers of MPWR common stock among trust and brokerage accounts. The filing shows a distribution of 1,000 shares from the Peter Rafferty and Eric Toothill 2021 Irrevocable Trust to an unrelated individual and 1,499 shares moved from Sciammas Siblings 2021 GRATs to the Rosalind Sciammas brokerage account, with a corresponding receipt of 1,499 shares into that brokerage account. The filing states no funds were exchanged for these transfers and that the reporting person lacks management, investment control or pecuniary interest over the 1,000‑share distribution.

Positive

• Transfers were non‑sale distributions with no funds exchanged, indicating no insider sale proceeds reported
• Reporting person disclosed lack of control over the 1,000‑share distribution, clarifying economic interest
• Filing names specific trust and brokerage accounts, supporting transparent beneficial ownership reporting

Negative

• Beneficial ownership changes are significant in aggregate (multiple trust and brokerage movements) which may complicate ownership tracking
• Some holdings reported as disposed (e.g., 102,325 shares) appear on the form without contextual explanation in the filing
• No information on whether transfers affect voting arrangements or future control of shares

Insights

Financial Analyst

TL;DR: Insider reported intra‑family trust transfers and brokerage reallocations; no sales or cash proceeds were recorded.

The Form 4 discloses non‑derivative transfers of MPWR common stock on 08/19/2025 involving family trusts and a brokerage account. These are documented as distributions or reallocations rather than disposals for value; the filer indicates no funds exchanged. From an equity‑ownership perspective, such transfers can change beneficial ownership reporting without indicating market liquidity events or insider selling. The filing also notes that the reporting person does not retain management or investment control over at least one distributed block, which reduces questions about retained economic interest in that parcel.

Corporate Governance Expert

TL;DR: Trustee executed trust distributions and account transfers; disclosures appear procedural with limited governance implications.

As trustee, the reporting person documented distributions from irrevocable trusts and GRATs to third parties and family accounts. The statements that no funds were exchanged and that the reporting person lacks management or pecuniary control over certain shares clarify potential conflicts of interest. These disclosures satisfy Section 16 transparency by reporting changes in beneficial ownership; there is no indication of transactions pursuant to Rule 10b5‑1, nor of compensatory or derivative exercises in this filing.

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^*

Sciammas Maurice

(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, WW Sales & Marketing

3. Date of Earliest Transaction (Month/Day/Year)
08/19/2025

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	08/19/2025		G		1,000	D	$0(1)	1,000	I	Peter Rafferty and Eric Toothill 2021Trust
Common Stock	08/19/2025		G		1,499	D	$0(2)	12,228	I	Various Sciammas GRATs
Common Stock	08/19/2025		G		1,499	A	$0(3)	1,499	I	Rosalind Sciammas Brokerage Account
Common Stock								102,325	D
Common Stock								44,930	I	Sciammas Family Trust
Common Stock								1,699	I	The Chloe Liliane Sciammas 2020 Irrevocable Trust
Common Stock								1,699	I	The Patrick Francis Sciammas 2020 Irrevocable 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								5,000	I	Clement Sciammas Family 2021 Trust
Common Stock								9,481	I	Maurice Sciammas Trust FBO Oski Crew
Common Stock								9,481	I	Christina Sciammas Trust FBO Oski Crew
Common Stock								1,499	I	Clement Sciammas Brokerage Account
Common Stock								4,015	I	By Sciammas Trust 2020

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. 1,000 shares were distributed from the Peter Rafferty and Eric Toothill 2021 Irrevocable Trust, on which the reporting person is a Trustee, to an individual who is not an immediate family member living in the same household of the reporting person. In addition, the Company has determined that the reporting person does not have any management or investment control or any other pecuniary interests over the shares. No funds were exchanged and no sale of shares occurred in the transfer.

2. 1,499 shares were distributed from the Sciammas Siblings 2021 GRATs, on which the reporting person is a Trustee, to the Rosalind Sciammas brokerage account. No funds were exchanged, and no sale of shares occurred in the transfer.

3. 1,499 shares were received by the Rosalind Sciammas brokerage account from Sciammas Siblings 2021 GRATs. No funds were exchanged, and no sale of shares occurred in the transfer

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Maurice Sciammas	08/19/2025
	** 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 transactions did Maurice Sciammas report for MPWR on 08/19/2025?

The Form 4 reports distributions and transfers of MPWR common stock on 08/19/2025, including 1,000 shares distributed from the Peter Rafferty and Eric Toothill 2021 Irrevocable Trust and 1,499 shares moved from Sciammas Siblings 2021 GRATs to the Rosalind Sciammas brokerage account.

Did the Form 4 report any sales or cash proceeds for MPWR (ticker: MPWR)?

No. The filing explicitly states that no funds were exchanged for the reported transfers; they are described as distributions or account reallocations, not sales.

What is Maurice Sciammas's role at Monolithic Power Systems (MPWR)?

The filing identifies Maurice Sciammas as an Officer with the title EVP, Worldwide Sales & Marketing and as a trustee of multiple family trusts.

Does the filing indicate Maurice Sciammas retains control or economic interest over distributed shares?

For the 1,000‑share distribution, the filing states the company determined the reporting person does not have management or investment control or any pecuniary interest in those shares.

Are there derivative transactions or option exercises reported in this Form 4?

No derivative securities, exercises, or option transactions are reported in Table II of this Form 4; the filing shows only non‑derivative common stock transfers.