STOCK TITAN

Small MPWR insider sale: EVP Sciammas (NASDAQ: MPWR) sells 30 shares via 10b5-1 plan

Filing Impact
(Neutral)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

MONOLITHIC POWER SYSTEMS INC EVP Maurice Sciammas reported a small pre-planned stock sale by a family trust. On May 4, 2026, the Clement Sciammas Trust sold 30 shares of MPWR common stock at $1,588.73 per share in an open-market transaction.

After this sale, the Clement Sciammas Trust held 1,209 shares. The filing also shows other indirect holdings in various Sciammas family trusts and GRATs, and 178,644 shares held directly. The sale was executed under a Rule 10b5-1 trading plan adopted on November 19, 2025, indicating it was pre-arranged.

Positive

  • None.

Negative

  • None.
Insider Sciammas Maurice
Role EVP, WW Sales & Marketing
Sold 30 shs ($48K)
Type Security Shares Price Value
Sale Common Stock 30 $1,588.73 $48K
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
holding Common Stock -- -- --
Holdings After Transaction: Common Stock — 1,209 shares (Indirect, Clement Sciammas Trust); Common Stock — 178,644 shares (Direct, null)
Footnotes (1)
  1. [object Object]
Shares sold 30 shares Open-market sale by Clement Sciammas Trust on May 4, 2026
Sale price $1,588.73 per share Price for the 30 MPWR shares sold on May 4, 2026
Trust holdings after sale 1,209 shares Clement Sciammas Trust position following the 30-share sale
Direct holdings 178,644 shares Common stock held directly by Maurice Sciammas as of May 4, 2026
Sciammas Family Trust holdings 49,460 shares Indirect holdings in Sciammas Family Trust
Various Sciammas GRATs holdings 26,660 shares Indirect holdings in various Sciammas GRATs
Net share change 30 shares net-sell transactionSummary netBuySellShares and netBuySellDirection
Rule 10b5-1 trading plan regulatory
"This transaction was made pursuant to a Rule 10b5-1 trading plan adopted on 11/19/2025."
A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.
open-market sale financial
"Transaction code S described as a sale in open market or private transaction."
An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.
indirect ownership financial
"Ownership type is marked as indirect with various Sciammas family trusts and GRATs."
Sciammas Family Trust financial
"Nature of ownership listed as Sciammas Family Trust for 49,460 common shares."
Various Sciammas GRATs financial
"Nature of ownership listed as Various Sciammas GRATs for 26,660 common shares."
SEC Form 4
FORM 4UNITED 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)
Director10% Owner
XOfficer (give title below)Other (specify below)
EVP, WW Sales & Marketing
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
05/04/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock178,644D
Common Stock05/04/2026S30(1)D$1,588.731,209IClement Sciammas Trust
Common Stock1,299IRosalind Sciammas Brokerage Account
Common Stock1,699IThe Joseph Roger Sciammas 2020 Irrevocable Trust
Common Stock2,000IRosalind Sciammas Family 2021 Trust
Common Stock49,460ISciammas Family Trust
Common Stock26,660IVarious Sciammas GRATs
Common Stock1,699IThe Patrick Francis Sciammas 2020 Irrevocable Trust
Common Stock4,015IBy Sciammas Trust 2020
Common Stock1,000IPeter Rafferty and Eric Toothill 2021Trust
Common Stock1,699IThe Chloe Liliane Sciammas 2020 Irrevocable Trust
Common Stock5,000IClement Sciammas Family 2021 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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Explanation of Responses:
1. This transaction was made pursuant to a Rule 10b5-1 trading plan adopted on 11/19/2025.
Remarks:
/s/ Saria Tseng, attorney-in-fact for Mr. Maurice Sciammas05/06/2026
** Signature of Reporting PersonDate
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 did MPWR EVP Maurice Sciammas report in this Form 4 filing?

EVP Maurice Sciammas reported that the Clement Sciammas Trust sold 30 shares of Monolithic Power Systems common stock at $1,588.73 per share on May 4, 2026. The sale was an open-market transaction executed under a pre-arranged Rule 10b5-1 plan.

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

Yes. The filing states the transaction was made under a Rule 10b5-1 trading plan adopted on November 19, 2025. Such plans pre-schedule trades, indicating the timing of this 30-share sale was set in advance rather than decided opportunistically.

How many MPWR shares did the Clement Sciammas Trust hold after the sale?

Following the reported transaction, the Clement Sciammas Trust held 1,209 shares of Monolithic Power Systems common stock. This reflects the position after selling 30 shares at $1,588.73 per share in the disclosed open-market sale on May 4, 2026.

What other MPWR holdings associated with Maurice Sciammas are shown in the Form 4?

The filing lists several indirect holdings in family trusts and GRATs, including 49,460 shares in the Sciammas Family Trust and 26,660 shares in various Sciammas GRATs. It also reports 178,644 shares of common stock held directly by Maurice Sciammas.

How many MPWR shares did Maurice Sciammas hold directly according to this Form 4?

According to the filing, Maurice Sciammas held 178,644 shares of Monolithic Power Systems common stock directly as of the reported date. This direct position is separate from multiple indirect holdings in various Sciammas family trusts and GRATs listed in the same Form 4.