Insider plans sale of 21,590 MPWR shares

A holder of MPWR common stock filed a notice of proposed sale of 21,590 shares under Rule 144.

Rhea-AI Filing Summary

A holder of MPWR common stock filed a notice of proposed sale of 21,590 shares under Rule 144. These shares have an aggregate market value of $25,148,679.70 and are to be sold through Morgan Stanley Smith Barney LLC on 02/04/2026 on the NASDAQ market.

The issuer had 48,710,953 shares of this class outstanding. The seller acquired the 21,590 shares on 02/03/2026 as performance-based restricted stock units from the issuer, with no separate cash payment noted.

FAQ

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

What does the MPWR Rule 144 filing disclose?

It discloses a planned sale of 21,590 MPWR common shares under Rule 144. The shares are valued at $25,148,679.70 and will be sold through Morgan Stanley Smith Barney LLC on NASDAQ, indicating an upcoming secondary market transaction by an existing holder.

How many MPWR shares are planned for sale in this Form 144?

The filing shows an intent to sell 21,590 MPWR common shares. This amount comes from performance-based restricted stock units recently acquired from the issuer, and will be sold through Morgan Stanley Smith Barney LLC, subject to Rule 144 conditions and market execution.

What is the aggregate market value of the MPWR shares to be sold?

The planned 21,590 MPWR common shares have an aggregate market value of $25,148,679.70. This value reflects the market pricing at the time of the filing and frames the potential dollar size of the holder’s planned secondary sale under Rule 144.

When is the approximate sale date for the MPWR Rule 144 shares?

The filing lists an approximate sale date of 02/04/2026 for the 21,590 MPWR shares. This date indicates when the holder expects to begin selling through Morgan Stanley Smith Barney LLC on NASDAQ, subject to Rule 144 and prevailing market conditions.

How were the MPWR shares in this Rule 144 notice acquired?

The 21,590 MPWR common shares were acquired on 02/03/2026 as performance-based restricted stock units from the issuer. The table notes the nature of the transaction as performance-based RSUs and indicates “N/A” for cash payment, reflecting equity-based compensation rather than a cash purchase.

How many MPWR shares are outstanding compared with this planned sale?

The issuer had 48,710,953 MPWR common shares outstanding, versus 21,590 shares planned for sale. This context shows the proposed transaction involves a small fraction of the total outstanding shares, framing the relative size of the Rule 144 sale.

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

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Accepted by SEC EDGAR 02/04/2026 - 08:50 PM EST 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	0001308647
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	Xiao Deming
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 NY 10004	21590	25148679.70	48710953	02/04/2026	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			21590	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

Nothing to Report

144: Remarks and Signature

Remarks
Date of Notice	02/04/2026
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/ Deming Xiao
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)