Monolithic Power (NASDAQ: MPWR) interim CFO sells 6 shares

Rhea-AI Filing Summary

MONOLITHIC POWER SYSTEMS, INC. (MPWR) officer Robert W. Dean II, Interim CFO, reported a small sale of 6 shares of common stock on 2026-08-17 at $1,413.64 per share. The footnote states the sale was made to cover tax withholding obligations upon the vesting of restricted stock units. After this transaction, he holds 7,126 shares directly and 65 shares indirectly held by Parent & Daughter.

Insider Trade Summary

Net Seller: 6 shares

Net Sell 2 txns

Insider DEAN ROBERT W II

Role Interim CFO

Sold 6 shs ($8K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1	6	$1,413.64	$8K
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 7,126 shares (Direct); Common Stock — 65 shares (Indirect, Held by Parent & Daughter)

Footnotes (1)

1. F1. The reported sale was to cover tax withholding obligations upon the vesting of restricted stock units.

Key Figures

Shares sold: 6 shares Sale price: $1,413.64 per share Direct holdings after transaction: 7,126 shares +2 more

5 metrics

Shares sold 6 shares Common stock sale on 2026-08-17 to cover tax withholding obligations

Sale price $1,413.64 per share Price for the 6 shares of common stock sold on 2026-08-17

Direct holdings after transaction 7,126 shares Direct MPWR common stock ownership reported following the sale

Indirect holdings 65 shares Indirect ownership described as Held by Parent & Daughter

Net shares sold 6 shares Net buy/sell shares in transaction summary (net-sell)

Key Terms

restricted stock units, tax withholding obligations, indirect ownership

3 terms

restricted stock units financial

"upon the vesting of restricted stock units."

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax withholding obligations financial

"sale was to cover tax withholding obligations upon the vesting"

indirect ownership financial

"Indirect ownership described as Held by Parent & Daughter"

FAQ

What insider transaction did MPWR Interim CFO Robert W. Dean II report?

He reported a sale of 6 MPWR common shares on 2026-08-17. According to a footnote, the sale was made to cover tax withholding obligations related to vesting restricted stock units, rather than as a discretionary portfolio sale.

At what price were the MPWR shares sold by the Interim CFO?

The 6 MPWR shares were sold at $1,413.64 per share. This price reflects the transaction linked to covering tax withholding obligations on vested restricted stock units, as disclosed in the filing footnote.

How many MPWR shares does the Interim CFO hold after this Form 4 transaction?

After the transaction, he holds 7,126 MPWR shares directly. In addition, a holding entry reports 65 shares indirectly, described as held by Parent & Daughter, indicating a separate indirect ownership position.

Was the MPWR insider sale made under a Rule 10b5-1 trading plan?

The filing’s Rule 10b5-1 checkbox is not marked as affirmed. Instead, a footnote explains that the 6-share sale was executed to cover tax withholding obligations for vested restricted stock units, not under a disclosed trading plan.

What indirect MPWR shareholding is reported for the Interim CFO?

The Form 4 lists an indirect ownership entry of 65 MPWR shares. This position is labeled as Held by Parent & Daughter, indicating the shares are held indirectly rather than in the officer’s direct name.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/19/2026 - 08:45 PM Accepted by SEC EDGAR 08/19/2026 - 08:44 PM Learn about SEC filing dates

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^*

DEAN ROBERT W II

(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)
	Interim CFO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/17/2026

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	08/17/2026		S		6(1)	D	$1,413.64	7,126	D
Common Stock								65	I	Held by Parent & Daughter

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 sale was to cover tax withholding obligations upon the vesting of restricted stock units.

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Robert W. Dean II	08/19/2026
	** 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)