STOCK TITAN

Monolithic Power (NASDAQ: MPWR) EVP sells 12,000 shares under 10b5-1 plan

Filing Impact
(Very High)
Filing Sentiment
(Very Negative)
Form Type
4

Rhea-AI Filing Summary

Monolithic Power Systems executive Maurice Sciammas, EVP of Worldwide Sales & Marketing, reported open-market sales of 12,000 shares of common stock on May 15, 2026. The shares were sold in multiple transactions at prices generally ranging from about $1,550 to $1,586 per share.

The filing states these sales were made under a Rule 10b5-1 trading plan adopted on November 24, 2025, indicating they were pre-arranged. Following the transactions, Sciammas directly holds 174,903 shares of Monolithic Power Systems common stock, in addition to various indirect holdings through family trusts and related accounts.

Positive

  • None.

Negative

  • None.
Insider Sciammas Maurice
Role EVP, WW Sales & Marketing
Sold 12,000 shs ($18.74M)
Type Security Shares Price Value
Sale Common Stock 3,741 $1,550.36 $5.80M
Sale Common Stock 1,717 $1,557.48 $2.67M
Sale Common Stock 2,010 $1,562.01 $3.14M
Sale Common Stock 2,020 $1,567.15 $3.17M
Sale Common Stock 1,312 $1,571.49 $2.06M
Sale Common Stock 703 $1,577.75 $1.11M
Sale Common Stock 447 $1,582.21 $707K
Sale Common Stock 50 $1,585.51 $79K
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Holdings After Transaction: Common Stock — 174,903 shares (Direct, null); Common Stock — 1,699 shares (Indirect, The Joseph Roger Sciammas 2020 Irrevocable Trust)
Footnotes (1)
  1. This transaction was made pursuant to a Rule 10b5-1 trading plan adopted on 11/24/2025. 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 $1,549.62 to $1,554.55. 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. 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 $1,554.59 to $1,559.37. 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. 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 $1,559.61 to $1,564.59. 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. 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 $1,564.75 to $1,569.67. 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. 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 $1,569.78 to $1,574.53. 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. 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 $1,574.9 to $1,579.7. 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. 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 $1,579.97 to $1,584.43. 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. 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 $1,585.17 to $1,586.76. 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.
Shares sold 12,000 shares Total common stock sold on May 15, 2026
Sale price example $1,550.36 per share One of several reported open-market sale prices
Highest price range $1,585.17–$1,586.76 Weighted average price range noted in a footnote
Lowest price range $1,549.62–$1,554.55 Weighted average price range noted in a footnote
Direct holdings after sale 174,903 shares Direct MPWR common stock owned following the transactions
Sciammas Family Trust holdings 51,023 shares Indirect MPWR holdings via Sciammas Family Trust
Various Sciammas GRATs holdings 25,097 shares Indirect MPWR holdings via various GRATs
10b5-1 plan adoption date November 24, 2025 Date the trading plan governing these sales was adopted
Rule 10b5-1 trading plan regulatory
"This transaction was made pursuant to a Rule 10b5-1 trading plan adopted on 11/24/2025."
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.
weighted average sale price financial
"The price is the weighted average sale price for the transactions reported on this line."
irrevocable trust financial
"The Chloe Liliane Sciammas 2020 Irrevocable Trust"
An irrevocable trust is a legal arrangement where an owner transfers assets into a separate entity managed by a trustee and gives up the power to modify or reclaim those assets. For investors it matters because putting stock or other holdings into such a trust can change who controls and benefits from the assets, affect taxes and creditor protection, and influence how easy it is to sell or value those holdings—like placing valuables in a locked safe overseen by someone else.
GRATs financial
"Various Sciammas GRATs"
open-market sale market
"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.
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)
05/15/2026
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 Stock05/15/2026S3,741(1)D$1,550.36(2)174,903D
Common Stock05/15/2026S1,717(1)D$1,557.48(3)173,186D
Common Stock05/15/2026S2,010(1)D$1,562.01(4)171,176D
Common Stock05/15/2026S2,020(1)D$1,567.15(5)169,156D
Common Stock05/15/2026S1,312(1)D$1,571.49(6)167,844D
Common Stock05/15/2026S703(1)D$1,577.75(7)167,141D
Common Stock05/15/2026S447(1)D$1,582.21(8)166,694D
Common Stock05/15/2026S50(1)D$1,585.51(9)166,644D
Common Stock1,699IThe Joseph Roger Sciammas 2020 Irrevocable Trust
Common Stock2,000IRosalind Sciammas Family 2021 Trust
Common Stock51,023ISciammas Family Trust
Common Stock25,097IVarious 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 Stock1,209IClement Sciammas Trust
Common Stock5,000IClement Sciammas Family 2021 Trust
Common Stock919IRosalind Sciammas Brokerage Account
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 11/24/2025.
2. 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 $1,549.62 to $1,554.55. 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.
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 $1,554.59 to $1,559.37. 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.
4. 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 $1,559.61 to $1,564.59. 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.
5. 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 $1,564.75 to $1,569.67. 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.
6. 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 $1,569.78 to $1,574.53. 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.
7. 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 $1,574.9 to $1,579.7. 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.
8. 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 $1,579.97 to $1,584.43. 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.
9. 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 $1,585.17 to $1,586.76. 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 Sciammas05/19/2026
** 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 insider activity did MPWR executive Maurice Sciammas report on this Form 4?

Maurice Sciammas reported selling 12,000 shares of Monolithic Power Systems common stock in open-market transactions on May 15, 2026. These trades were executed across multiple price points generally between about $1,550 and $1,586 per share, according to the filing details.

At what prices did Maurice Sciammas sell MPWR shares on May 15, 2026?

The Form 4 shows Sciammas’ MPWR share sales occurred at prices generally between about $1,550 and $1,586 per share. Footnotes describe weighted average prices for each line, with detailed per-price breakdowns available upon request from the company or regulators.

How many MPWR shares does Maurice Sciammas hold after the reported sales?

After the reported May 15, 2026 sales, Sciammas directly holds 174,903 shares of Monolithic Power Systems common stock. The filing also lists additional indirect holdings through family trusts, GRATs, and brokerage accounts associated with the Sciammas family.

Were Maurice Sciammas’ MPWR stock sales made under a Rule 10b5-1 plan?

Yes. A footnote states the 12,000-share sale was made under a Rule 10b5-1 trading plan adopted on November 24, 2025. Such plans pre-schedule trades, so the timing reflects the plan’s terms rather than day-to-day market decisions.

How many MPWR shares did Sciammas sell in total according to the Form 4 summary?

The transaction summary reports total sales of 12,000 Monolithic Power Systems shares. All reported sales are coded as open-market transactions, with no purchases, option exercises, gifts, or tax-withholding-related dispositions included in this particular filing.