Monolithic Power (NASDAQ: MPWR) interim CFO sells to cover stock-award taxes

Rhea-AI Filing Summary

MONOLITHIC POWER SYSTEMS, INC. (MPWR) reported insider activity by Interim CFO Robert W. Dean II. On 2026-08-24, he sold 32 shares of common stock in open-market transactions at a weighted average price of $1,297.72 per share to cover tax withholding obligations upon the vesting of restricted stock units. The sale prices ranged from $1,296.07 to $1,298.01. On the same date, he also disposed of 5 shares through a transfer from his direct holdings to an individual who is not an immediate family member sharing the same household; no funds were exchanged, no sale occurred, and he no longer retains any pecuniary interest in those shares. After these transactions, an additional 65 shares of common stock are reported as held indirectly, described as "Held by Parent & Daughter."

Insider Trade Summary

Net Seller: 37 shares

Net Sell 3 txns

Insider DEAN ROBERT W II

Role Interim CFO

Sold 32 shs ($42K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	32	$1,297.72	$42K
Other	Common Stock F3	5	$0.00	$0.00
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 7,089 shares (Direct); Common Stock — 65 shares (Indirect, Held by Parent & Daughter)

Footnotes (3)

1. F1. The reported sale was to cover tax withholding obligations upon the vesting of restricted stock units.
2. F2. 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 $1,296.07 to $1,298.01. 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. F3. The reported transaction involved a transfer of securities from the reporting person's direct holdings to an individual who is not an immediate family member sharing the same household. No funds were exchanged and no sale of shares occurred in the transfer. Following the completion of the transfer, the reporting person no longer retains any pecuniary interest in the shares.

Key Figures

Shares sold: 32 shares of Common Stock Weighted average sale price: $1,297.72 per share Sale price range: $1,296.07 to $1,298.01 per share +2 more

5 metrics

Shares sold 32 shares of Common Stock Open-market sale on 2026-08-24 to cover tax withholding on RSU vesting

Weighted average sale price $1,297.72 per share Weighted average for the 32 shares sold on 2026-08-24

Sale price range $1,296.07 to $1,298.01 per share Range of prices for the 32-share sale on 2026-08-24

Shares transferred 5 shares of Common Stock Non-cash transfer from direct holdings; no pecuniary interest retained

Indirect holdings 65 shares of Common Stock Reported as indirectly owned, described as "Held by Parent & Daughter"

Key Terms

restricted stock units, weighted average sale price, pecuniary interest

3 terms

restricted stock units financial

"to cover tax withholding obligations 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.

weighted average sale price financial

"The price is the weighted average sale price for the transactions"

pecuniary interest financial

"the reporting person no longer retains any pecuniary interest in the shares"

FAQ

What insider transactions did MPWR Interim CFO Robert W. Dean II report on 2026-08-24?

He reported a sale of 32 MPWR common shares in open-market transactions and a disposition of 5 shares via a transfer to a non–immediate family member, with no funds exchanged and no remaining pecuniary interest in the transferred shares.

At what prices were the 32 MPWR shares sold by the Interim CFO?

The 32 MPWR shares were sold at a weighted average price of $1,297.72 per share. The individual sale prices for these transactions ranged from $1,296.07 to $1,298.01, according to the filing footnote.

Why did the MPWR Interim CFO sell 32 shares of common stock?

The filing states that the 32-share sale was made to cover tax withholding obligations arising from the vesting of restricted stock units, indicating it was tied to equity compensation rather than a discretionary open-market sale for investment purposes.

What was the nature of the 5-share disposition reported by the MPWR Interim CFO?

The 5-share disposition was a transfer from direct holdings to an individual who is not an immediate family member sharing the same household. The filing notes that no funds were exchanged, no sale occurred, and the reporting person no longer has any pecuniary interest in those shares.

How many MPWR shares does the Interim CFO hold indirectly after these transactions?

After the reported transactions, the filing lists an indirect holding of 65 MPWR common shares, described as "Held by Parent & Daughter", indicating the shares are held through that relationship rather than directly.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/26/2026 - 07:23 PM Accepted by SEC EDGAR 08/26/2026 - 07:22 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)
08/24/2026

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	08/24/2026		S		32(1)	D	$1,297.72(2)	7,094	D
Common Stock	08/24/2026		J		5	D	$0(3)	7,089	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.

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 $1,296.07 to $1,298.01. 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 reported transaction involved a transfer of securities from the reporting person's direct holdings to an individual who is not an immediate family member sharing the same household. No funds were exchanged and no sale of shares occurred in the transfer. Following the completion of the transfer, the reporting person no longer retains any pecuniary interest in the shares.

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Robert W. Dean II	08/26/2026
	** 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)