Insider plans sale of 1,286 shares of common stock

A holder of common stock has filed a Form 144 notice to potentially sell 1,286 shares, with an aggregate market value of $1,505,526.00.

Rhea-AI Filing Summary

A holder of common stock has filed a Form 144 notice to potentially sell 1,286 shares, with an aggregate market value of $1,505,526.00. The proposed sale is through Morgan Stanley Smith Barney LLC on the NASDAQ, with an approximate sale date of 02/06/2026. These shares were acquired on 02/03/2026 as performance-based restricted stock units from the issuer. The notice also lists prior sales over the past three months by Saria Tseng, including 20,000 shares sold on 11/25/2025, 20,000 on 11/26/2025, and 21,590 on 02/04/2026, with disclosed gross proceeds for each transaction.

FAQ

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

What planned stock sale is disclosed in this MPWR Form 144 filing?

The filing discloses a planned sale of 1,286 shares of common stock with an aggregate market value of $1,505,526.00. The shares are expected to be sold on NASDAQ through Morgan Stanley Smith Barney LLC around 02/06/2026.

How were the 1,286 MPWR shares in this Form 144 acquired?

The 1,286 shares covered by the notice were acquired on 02/03/2026 as performance-based restricted stock units from the issuer. The same date is listed for acquisition and payment, and the form notes the nature of payment as N/A for this equity-based award.

What recent stock sales by Saria Tseng are listed in the MPWR Form 144?

The filing lists three recent common stock sales by Saria Tseng: 20,000 shares on 11/25/2025, another 20,000 shares on 11/26/2025, and 21,590 shares on 02/04/2026, each with specific gross proceeds disclosed in dollars.

Which broker is handling the proposed MPWR share sale under this Form 144?

The proposed sale will be handled by Morgan Stanley Smith Barney LLC Executive Financial Services, located at 1 New York Plaza, 8th Floor, New York, FL 10004. The filing also specifies that the sale is planned for execution on the NASDAQ exchange.

How many MPWR shares are outstanding according to this Form 144?

The document reports 48,710,953 shares of common stock outstanding. This figure provides context for the potential sale of 1,286 shares under Rule 144, indicating the relative size of the proposed transaction compared with total outstanding shares.

What does the Rule 144 representation section require in this MPWR filing?

The signer represents that they do not know any material adverse information about the issuer’s current or prospective operations that has not been publicly disclosed. If a Rule 10b5-1 trading plan exists, the signature also confirms this representation as of the plan’s adoption date.

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Accepted by SEC EDGAR 02/06/2026 - 09:04 PM Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001312593
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	MONOLITHIC POWER SYSTEMS INC
SEC File Number	000-51026
Address of Issuer	1555 PALM BEACH LAKES BLVD. WEST PALM BEACH FLORIDA 33401
Phone	561-839-3999
Name of Person for Whose Account the Securities are To Be Sold	Tseng Saria
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common Stock	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York FL 10004	1286	1505526.00	48710953	02/06/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common Stock	02/03/2026	Performance-based restricted stock units	Issuer			1286	02/03/2026	N/A

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
SARIA TSENG 1555 PALM BEACH LAKES BLVD. WEST PALM BEACH FL 33401	Common Stock	11/25/2025	20000	18083600.00
SARIA TSENG 1555 PALM BEACH LAKES BLVD. WEST PALM BEACH FL 33401	Common Stock	11/26/2025	20000	18529300.00
SARIA TSENG 1555 PALM BEACH LAKES BLVD. WEST PALM BEACH FL 33401	Common Stock	02/04/2026	21590	25285344.00

144: Remarks and Signature

Remarks
Date of Notice	02/06/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Saria Tseng
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)