SEC FORM 3

SEC FORM 3 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

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)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	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)

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.

New insider Dean Robert W Ii claimed ownership of 8,125 shares (SEC Form 3)