Monolithic Power CEO sells 34,000 shares in plan

Monolithic Power Systems CEO Michael Hsing, who also serves as a director, sold a total of 34,000 shares of common stock on February 10, 2026 in a series of open-market transactions under a pre-arranged Rule 10b5-1 trading plan adopted on August 28, 2025.

Rhea-AI Filing Summary

Monolithic Power Systems CEO Michael Hsing, who also serves as a director, sold a total of 34,000 shares of common stock on February 10, 2026 in a series of open-market transactions under a pre-arranged Rule 10b5-1 trading plan adopted on August 28, 2025. The reported weighted average sale prices on that date ranged from about $1,128.88 to $1,197.26 per share. Following these sales, Hsing directly owns 954,234 shares and indirectly holds 133,040 shares through the M Hsing 04 Trust and 12,825 shares through the ZH Family 2020 Trust.

Insider Trade Summary

Net Seller: 34,000 shares

Net Sell 11 txns

Insider Hsing Michael

Role CEO

Sold 34,000 shs ($38.84M)

Type	Security	Shares	Price	Value
Sale	Common Stock	4,302	$1,132.01	$4.87M
Sale	Common Stock	6,325	$1,136.75	$7.19M
Sale	Common Stock	16,080	$1,141.88	$18.36M
Sale	Common Stock	3,864	$1,145.90	$4.43M
Sale	Common Stock	1,215	$1,151.11	$1.40M
Sale	Common Stock	694	$1,154.96	$802K
Sale	Common Stock	360	$1,161.41	$418K
Sale	Common Stock	880	$1,176.04	$1.03M
Sale	Common Stock	280	$1,197.26	$335K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 954,234 shares (Direct); Common Stock — 133,040 shares (Indirect, by M Hsing 04 Trust); Common Stock — 12,825 shares (Indirect, ZH Family 2020 Trust)

Footnotes (9)

1. F1. These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
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 $1,128.88 to $1,133.86. 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 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 $1,133.92 to $1,138.90. 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. F4. 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 $1,138.96 to $1,143.96. 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. F5. 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 $1,144.03 to $1,149.00. 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. F6. 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 $1,149.04 to $1,154.00. 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. F7. 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 $1,154.09 to $1,155.86. 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. F8. 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 $1,159.96 to $1,163.96. 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. F9. 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 $1,172.65 to $1,177.08. 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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did MPWR CEO Michael Hsing report?

Michael Hsing reported open-market sales of 34,000 shares of Monolithic Power Systems common stock. These trades occurred on February 10, 2026 and were executed in multiple blocks at different prices as part of a disclosed Rule 10b5-1 trading plan.

At what prices did the MPWR CEO sell his Monolithic Power shares?

The CEO’s reported weighted average sale prices ranged from about $1,128.88 to $1,197.26 per share. Each transaction line reflects a weighted average, with detailed price ranges available to regulators, the issuer, or shareholders upon request.

How many MPWR shares does CEO Michael Hsing still own after these sales?

After the reported sales, Michael Hsing directly owns 954,234 Monolithic Power Systems shares. He also has indirect beneficial ownership of 133,040 shares via the M Hsing 04 Trust and 12,825 shares via the ZH Family 2020 Trust, according to the filing.

Were the MPWR CEO’s stock sales made under a Rule 10b5-1 plan?

Yes. The filing states the transactions were made under a Rule 10b5-1 trading plan adopted on August 28, 2025. Such plans pre-schedule trades, allowing insiders to sell shares over time according to predefined instructions.

What role does Michael Hsing hold at Monolithic Power Systems (MPWR)?

Michael Hsing is identified as both a director and the CEO of Monolithic Power Systems. The filing classifies him as an officer with the title of CEO, providing context for his status as an insider under U.S. securities regulations.

How is indirect ownership reported for MPWR CEO Michael Hsing?

The filing reports indirect beneficial ownership through two trusts: 133,040 shares held by the M Hsing 04 Trust and 12,825 shares held by the ZH Family 2020 Trust. These positions are listed as indirect holdings separate from his directly owned shares.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 4 Insider Transactions: What Each Field Means →

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Accepted by SEC EDGAR 02/12/2026 - 02:45 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).

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^*

Hsing Michael

(Last) (First) (Middle)

1555 PALM BEACH LAKES BLVD.

(Street)

WEST PALM BEACH FL 33401

(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)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	CEO

3. Date of Earliest Transaction (Month/Day/Year)
02/10/2026

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	02/10/2026		S		4,302(1)	D	$1,132.01(2)	983,932	D
Common Stock	02/10/2026		S		6,325(1)	D	$1,136.75(3)	977,607	D
Common Stock	02/10/2026		S		16,080(1)	D	$1,141.88(4)	961,527	D
Common Stock	02/10/2026		S		3,864(1)	D	$1,145.9(5)	957,663	D
Common Stock	02/10/2026		S		1,215(1)	D	$1,151.11(6)	956,448	D
Common Stock	02/10/2026		S		694(1)	D	$1,154.96(7)	955,754	D
Common Stock	02/10/2026		S		360(1)	D	$1,161.41(8)	955,394	D
Common Stock	02/10/2026		S		880(1)	D	$1,176.04(9)	954,514	D
Common Stock	02/10/2026		S		280(1)	D	$1,197.26	954,234	D
Common Stock								133,040	I	by M Hsing 04 Trust
Common Stock								12,825	I	ZH Family 2020 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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.

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 $1,128.88 to $1,133.86. 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 $1,133.92 to $1,138.90. 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 $1,138.96 to $1,143.96. 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 $1,144.03 to $1,149.00. 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 $1,149.04 to $1,154.00. 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 $1,154.09 to $1,155.86. 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 $1,159.96 to $1,163.96. 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 $1,172.65 to $1,177.08. 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. Michael R. Hsing	02/12/2026
	** 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.