Interim CFO of Monolithic Power (MPWR) details initial share ownership

Rhea-AI Filing Summary

Monolithic Power Systems interim CFO Robert W. Dean II filed an initial ownership report showing his stake in the company’s common stock. He reports 8,060 shares held directly, which include 1,420 restricted stock units that vest over scheduled dates through February 15, 2030, subject to continued employment. He also reports 65 shares held indirectly, described as being held by “Parent & Daughter.” This filing does not reflect new buying or selling activity, but establishes his current ownership position as an executive officer.

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

DEAN ROBERT W II

(Last) (First) (Middle)

1555 PALM BEACH LAKES BLVD.

(Street)

WEST PALM BEACH FL 33401

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
02/27/2026

3. Issuer Name and Ticker or Trading Symbol
MONOLITHIC POWER SYSTEMS INC [ MPWR ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

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

5. 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	8,060(1)	D
Common Stock	65	I	Held by Parent & Daughter

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Includes an aggregate of 1,420 shares of restricted stock units that vest, subject to continued employment, as follows: 11 shares on 05/15/2026; 59 shares on 05/22/2026; 11 shares on 08/15/2026; 61 shares on 08/22/2026; 12 shares on 11/15/2026; 59 shares on 11/22/2026; 400 shares on 02/03/2027; 11 shares on 02/15/2027; 63 shares on 02/22/2027; 12 shares on 05/15/2027; 39 shares on 05/22/2027; 11 shares on 08/15/2027; 39 shares on 08/22/2027; 12 shares on 11/15/2027; 39 shares on 11/22/2027; 400 shares on 02/03/2028; 11 shares on 02/15/2028; 40 shares on 02/22/2028; 11 shares on 05/15/2028; 9 shares on 05/22/2028; 12 shares on 08/15/2028; 10 shares on 08/22/2028; 11 shares on 11/15/2028; 9 shares on 11/22/2028; 12 shares on 02/15/2029; 10 shares on 02/22/2029; 11 shares on 05/15/2029; 12 shares on 08/15/2029; 11 shares on 11/15/2029; and 12 shares on 02/15/2030.

Remarks:

	/s/ Saria Tseng, attorney-in-fact for Mr. Robert W. Dean II	03/09/2026
	** 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 5 (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.

FAQ

What does the Form 3 filing by MPWR interim CFO Robert W. Dean II show?

The Form 3 shows Robert W. Dean II’s initial ownership in MPWR common stock, including 8,060 directly held shares and 65 indirectly held shares. It establishes his stake as an officer rather than indicating new buying or selling activity.

How many MPWR shares does Robert W. Dean II report owning directly and indirectly?

Robert W. Dean II reports 8,060 MPWR common shares held directly and 65 shares held indirectly through an account labeled “Parent & Daughter.” These totals define his reported beneficial ownership at the time of the Form 3 filing.

What restricted stock units are included in Robert W. Dean II’s MPWR holdings?

His reported MPWR holdings include 1,420 restricted stock units. These RSUs vest on multiple dates from May 15, 2026 through February 15, 2030, and each vesting tranche remains subject to his continued employment with the company.

Does Robert W. Dean II’s MPWR Form 3 indicate recent stock purchases or sales?

No, the MPWR Form 3 reflects holdings rather than transactions. It lists shares and restricted stock units owned directly and indirectly by Robert W. Dean II, but does not show recent purchases or sales of company stock.

How is the indirect ownership described in the MPWR Form 3 for Robert W. Dean II?

The Form 3 reports 65 MPWR common shares held indirectly with the nature of ownership described as “Held by Parent & Daughter.” This indicates those shares are owned through a related account or entity rather than in his own name.

Over what period do Robert W. Dean II’s MPWR restricted stock units vest?

His 1,420 MPWR restricted stock units vest in small tranches on specified dates from May 15, 2026 through February 15, 2030. Each vesting date is contingent on his continued employment with Monolithic Power Systems.