Monolithic Power Systems CEO sells 30,000 shares

Q: What weighted-average prices were reported for MPWR CEO Michael Hsing's sales?

The reported weighted-average prices per share were $1,323.31 for 596 shares, $1,328.54 for 2,121, $1,333.34 for 1,111, $1,338.66 for 2,949, $1,343.76 for 5,783, $1,347.15 for 6,343, $1,351.43 for 10,967, and $1,356.94 for 130 shares.

A reported 10,967-share sale entry carried a weighted-average price of $1,351.43 per share.

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Rhea-AI Filing Summary

Monolithic Power Systems, Inc. (MPWR) CEO and director Michael Hsing reported selling 30,000 common shares on September 28, 2026, across eight sale entries. The sales were made under a Rule 10b5-1 trading plan adopted May 29, 2026. Separate position entries list 133,040 shares held by M Hsing 04 Trust and 12,825 shares held by ZH Family 2020 Trust.

Insights

Analyzing...

Insider Trade Summary 10b5-1

Net Seller: 30,000 shares

Net Sell 10 txns

Insider Hsing Michael

Role CEO

Sold 30,000 shs ($40.35M)

Type	Security	Shares	Price	Value
Sale	Common Stock ^{F1, F3, F2}	596	$1,323.31	$789K
Sale	Common Stock ^{F1, F4}	2,121	$1,328.54	$2.82M
Sale	Common Stock ^{F1, F5}	1,111	$1,333.34	$1.48M
Sale	Common Stock ^{F1, F6}	2,949	$1,338.66	$3.95M
Sale	Common Stock ^{F1, F7}	5,783	$1,343.76	$7.77M
Sale	Common Stock ^{F1, F8}	6,343	$1,347.15	$8.54M
Sale	Common Stock ^{F1, F9}	10,967	$1,351.43	$14.82M
Sale	Common Stock ^{F1, F10}	130	$1,356.94	$176K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 818,264 shares (Direct); Common Stock — 133,040 shares (Indirect, by M Hsing 04 Trust); Common Stock — 12,825 shares (Indirect, ZH Family 2020 Trust)

Footnotes (10)

F1. These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 05/29/2026.
F2. Ending balance includes 1 share acquired on August 17, 2026, through the Company's qualified ESPP program.
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 $1,320.64 to $1,325.61. 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.
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 $1,325.65 to $1,330.62. 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.
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 $1,330.65 to $1,335.51. 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.
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 $1,335.68 to $1,340.66. 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.
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 $1,340.69 to $1,345.65. 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.
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 $1,345.66 to $1,350.47. 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.
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 $1,350.84 to $1,355.11. 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.
F10. 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 $1,356.78 to $1,357.00. 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.

Key Figures

Weighted-average sale price: $1,323.31 per share Weighted-average sale price: $1,328.54 per share Weighted-average sale price: $1,333.34 per share +5 more

8 metrics

Weighted-average sale price $1,323.31 per share 596 shares sold September 28, 2026

Weighted-average sale price $1,328.54 per share 2,121 shares sold September 28, 2026

Weighted-average sale price $1,333.34 per share 1,111 shares sold September 28, 2026

Weighted-average sale price $1,338.66 per share 2,949 shares sold September 28, 2026

Weighted-average sale price $1,343.76 per share 5,783 shares sold September 28, 2026

Weighted-average sale price $1,347.15 per share 6,343 shares sold September 28, 2026

Weighted-average sale price $1,351.43 per share 10,967 shares sold September 28, 2026

Weighted-average sale price $1,356.94 per share 130 shares sold September 28, 2026

Key Terms

Rule 10b5-1 trading plan, weighted average sale price, qualified ESPP program

3 terms

Rule 10b5-1 trading plan regulatory

"Rule 10b5-1 trading plan adopted by the reporting person"

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"

qualified ESPP program financial

"through the Company's qualified ESPP program"

FAQ

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

How many MPWR shares did the CEO sell?

Monolithic Power Systems CEO Michael Hsing reported selling 30,000 common shares on September 28, 2026, across eight sale entries under a Rule 10b5-1 trading plan adopted May 29, 2026.

What weighted-average prices were reported for MPWR CEO Michael Hsing's sales?

The reported weighted-average prices per share were $1,323.31 for 596 shares, $1,328.54 for 2,121, $1,333.34 for 1,111, $1,338.66 for 2,949, $1,343.76 for 5,783, $1,347.15 for 6,343, $1,351.43 for 10,967, and $1,356.94 for 130 shares.

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Available on EDGAR 09/30/2026 - 05:21 PM Accepted by SEC EDGAR 09/30/2026 - 05:21 PM

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^*

Hsing Michael

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/28/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	09/28/2026		S		596⁽¹⁾	D	$1,323.31⁽³⁾	847,668⁽²⁾	D
Common Stock	09/28/2026		S		2,121⁽¹⁾	D	$1,328.54⁽⁴⁾	845,547	D
Common Stock	09/28/2026		S		1,111⁽¹⁾	D	$1,333.34⁽⁵⁾	844,436	D
Common Stock	09/28/2026		S		2,949⁽¹⁾	D	$1,338.66⁽⁶⁾	841,487	D
Common Stock	09/28/2026		S		5,783⁽¹⁾	D	$1,343.76⁽⁷⁾	835,704	D
Common Stock	09/28/2026		S		6,343⁽¹⁾	D	$1,347.15⁽⁸⁾	829,361	D
Common Stock	09/28/2026		S		10,967⁽¹⁾	D	$1,351.43⁽⁹⁾	818,394	D
Common Stock	09/28/2026		S		130⁽¹⁾	D	$1,356.94⁽¹⁰⁾	818,264	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 05/29/2026.

2. Ending balance includes 1 share acquired on August 17, 2026, through the Company's qualified ESPP program.

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 $1,320.64 to $1,325.61. 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 $1,325.65 to $1,330.62. 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 $1,330.65 to $1,335.51. 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 $1,335.68 to $1,340.66. 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 $1,340.69 to $1,345.65. 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 $1,345.66 to $1,350.47. 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 $1,350.84 to $1,355.11. 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.

10. 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 $1,356.78 to $1,357.00. 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.

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Michael R. Hsing	09/30/2026
	** 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)

Source: View Original Filing on SEC EDGAR