Monolithic Power CFO sells shares under trading plan

Monolithic Power Systems executive vice president and CFO Theodore Blegen reported multiple open‑market sales of common stock on February 2, 2026 under a pre‑arranged Rule 10b5‑1 trading plan.

Rhea-AI Filing Summary

Monolithic Power Systems executive vice president and CFO Theodore Blegen reported multiple open‑market sales of common stock on February 2, 2026 under a pre‑arranged Rule 10b5‑1 trading plan. The trades involved small blocks of shares at weighted average prices ranging roughly from $1,110.14 to $1,139.54 per share. After these transactions, Blegen directly beneficially owned 65,333 common shares and indirectly held 5,331 shares in each of two irrevocable trusts for Sarah N. Blegen and Theodore F. Blegen.

Insider Trade Summary

Net Seller: 3,000 shares

Net Sell 19 txns

Insider BLEGEN THEODORE

Role EVP and CFO

Sold 3,000 shs ($3.39M)

Type	Security	Shares	Price	Value
Sale	Common Stock	220	$1,110.58	$244K
Sale	Common Stock	40	$1,117.11	$45K
Sale	Common Stock	80	$1,120.77	$90K
Sale	Common Stock	40	$1,122.56	$45K
Sale	Common Stock	200	$1,126.58	$225K
Sale	Common Stock	80	$1,127.39	$90K
Sale	Common Stock	240	$1,128.43	$271K
Sale	Common Stock	240	$1,129.28	$271K
Sale	Common Stock	320	$1,130.48	$362K
Sale	Common Stock	198	$1,131.70	$224K
Sale	Common Stock	322	$1,132.67	$365K
Sale	Common Stock	379	$1,133.47	$430K
Sale	Common Stock	241	$1,134.41	$273K
Sale	Common Stock	120	$1,135.49	$136K
Sale	Common Stock	120	$1,136.35	$136K
Sale	Common Stock	80	$1,137.81	$91K
Sale	Common Stock	80	$1,139.49	$91K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 65,333 shares (Direct); Common Stock — 5,331 shares (Indirect, Irrevocable Trust FBO Sarah N. Blegen); Common Stock — 5,331 shares (Indirect, Irrevocable Trust FBO Theodore F. Blegen)

Footnotes (15)

1. F1. These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 2/26/2025.
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 $1,110.14 to $1,110.68. 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 $1,126.50 to $1,126.71. 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 $1,127.28 to $1,127.49. 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 $1,128.32 to $1,128.64. 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 $1,129.07 to $1,129.60. 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 $1,130.18 to $1,130.95. 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 $1,131.38 to $1,131.91. 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 $1,132.33 to $1,132.84. 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. 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 $1,133.00 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.
11. F11. 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 $1,134.00 to $1,134.78. 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.
12. F12. 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 $1,135.09 to $1,135.71. 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.
13. F13. 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 $1,136.18 to $1,136.69. 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.
14. F14. 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 $1,139.44 to $1,139.54. 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.
15. F15. Ending balance has been adjusted for a one share rounding difference.

FAQ

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

What insider activity did MPWR report for its CFO on this Form 4?

Monolithic Power Systems reported that EVP and CFO Theodore Blegen sold multiple small blocks of common stock on February 2, 2026, in open‑market transactions executed under a Rule 10b5‑1 trading plan, with each sale reported at a specific weighted average price.

On what date did MPWR CFO Theodore Blegen sell common stock?

All reported transactions occurred on February 2, 2026. Each line in the Form 4’s Table I lists that same transaction date for sales of Monolithic Power Systems common stock, reflecting a series of planned trades rather than activity spread over multiple days.

What prices did the MPWR CFO receive for the reported stock sales?

Each sale line shows a weighted average price per share, with detailed footnotes. Across the reported trades, the weighted averages correspond to price ranges from $1,110.14 up to $1,139.54 per share for Monolithic Power Systems common stock on February 2, 2026.

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

Following the reported February 2, 2026 trades, Theodore Blegen beneficially owned 65,333 Monolithic Power Systems common shares directly. He also had indirect beneficial ownership of 5,331 common shares in each of two irrevocable trusts for Sarah N. Blegen and Theodore F. Blegen.

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

Yes. A footnote states the transactions were made under a Rule 10b5‑1 trading plan adopted by the reporting person on February 26, 2025. Such plans allow pre‑scheduled trading, helping executives systematically sell shares over time under predetermined instructions.

What indirect MPWR share holdings are reported for the CFO?

In addition to his direct holdings, the filing shows indirect beneficial ownership of 5,331 Monolithic Power Systems common shares held by an irrevocable trust for Sarah N. Blegen and another 5,331 shares held by an irrevocable trust for Theodore F. Blegen, both reported as indirect interests.

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Accepted by SEC EDGAR 02/04/2026 - 10:10 AM 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^*

BLEGEN THEODORE

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP and CFO

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

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	02/02/2026		S		220(1)	D	$1,110.58(2)	68,112	D
Common Stock	02/02/2026		S		40(1)	D	$1,117.11	68,072	D
Common Stock	02/02/2026		S		80(1)	D	$1,120.77	67,992	D
Common Stock	02/02/2026		S		40(1)	D	$1,122.56	67,952	D
Common Stock	02/02/2026		S		200(1)	D	$1,126.58(3)	67,752	D
Common Stock	02/02/2026		S		80(1)	D	$1,127.39(4)	67,672	D
Common Stock	02/02/2026		S		240(1)	D	$1,128.43(5)	67,432	D
Common Stock	02/02/2026		S		240(1)	D	$1,129.28(6)	67,192	D
Common Stock	02/02/2026		S		320(1)	D	$1,130.48(7)	66,872	D
Common Stock	02/02/2026		S		198(1)	D	$1,131.7(8)	66,674	D
Common Stock	02/02/2026		S		322(1)	D	$1,132.67(9)	66,352	D
Common Stock	02/02/2026		S		379(1)	D	$1,133.47(10)	65,973	D
Common Stock	02/02/2026		S		241(1)	D	$1,134.41(11)	65,732	D
Common Stock	02/02/2026		S		120(1)	D	$1,135.49(12)	65,612	D
Common Stock	02/02/2026		S		120(1)	D	$1,136.35(13)	65,492	D
Common Stock	02/02/2026		S		80(1)	D	$1,137.81	65,412	D
Common Stock	02/02/2026		S		80(1)	D	$1,139.49(14)	65,333(15)	D
Common Stock								5,331	I	Irrevocable Trust FBO Sarah N. Blegen
Common Stock								5,331	I	Irrevocable Trust FBO Theodore F. Blegen

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 2/26/2025.

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 $1,110.14 to $1,110.68. 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 $1,126.50 to $1,126.71. 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 $1,127.28 to $1,127.49. 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 $1,128.32 to $1,128.64. 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 $1,129.07 to $1,129.60. 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 $1,130.18 to $1,130.95. 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 $1,131.38 to $1,131.91. 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 $1,132.33 to $1,132.84. 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 $1,133.00 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.

11. 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 $1,134.00 to $1,134.78. 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.

12. 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 $1,135.09 to $1,135.71. 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.

13. 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 $1,136.18 to $1,136.69. 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.

14. 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 $1,139.44 to $1,139.54. 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.

15. Ending balance has been adjusted for a one share rounding difference.

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Bernie Blegen	02/02/2026
	** 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.