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
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 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
1. Name and Address of Reporting Person*
Xiao Deming
(Last) (First) (Middle)
79 GREAT OAKS BLVD
(Street)
SAN JOSE CA 95119
(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)
Pres. of MPS Asia Operations
3. Date of Earliest Transaction (Month/Day/Year)
08/07/2013
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 08/07/2013 M(1) 40,000 A $17.92(2) 121,065 D
Common Stock 08/07/2013 S(1) 40,000 D $27 81,065 D
Common Stock 08/08/2013 A 192(3) A $0.0 81,257 D
Common Stock 08/08/2013 S(4) 102 D $28.28 81,155 D
Common Stock 08/08/2013 S(4) 2,167 D $28.283 78,988 D
Common Stock 08/09/2013 M 1,429 A $15.03(2) 13,214 I by Spouse
Common Stock 08/09/2013 M 941 A $17.92 14,155 I by Spouse
Common Stock 08/09/2013 M 141 A $14.89 14,296 I by Spouse
Common Stock 08/09/2013 M 470 A $15.03 14,766 I by Spouse
Common Stock 08/09/2013 S 1,429 D $28.31 13,337 I by Spouse
Common Stock 08/09/2013 S 941 D $28.31 12,396 I by Spouse
Common Stock 08/09/2013 S 141 D $28.31 12,255 I by Spouse
Common Stock 08/09/2013 S 470 D $28.31 11,785 I by Spouse
Common Stock 08/09/2013 S 3,628 D $28.31 8,157 I by Spouse
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
Non-Qualified Stock Option (right to buy) $18.77(2) 08/07/2013 M(1) 40,000 08/03/2009 08/03/2014 Common Stock 40,000 $0.0 0 D
Non-Qualified Stock Option (right to buy) $14.89 08/09/2013 M 141 12/28/2012 10/28/2015 Common Stock 141 $0.0 0 I by Spouse
Non-Qualified Stock Option (right to buy) $15.03 08/09/2013 M 470 12/28/2012 10/28/2015 Common Stock 470 $0.0 0 I by Spouse
Non-Qualified Stock Option (right to buy) $15.74(2) 08/08/2013 M 1,429 10/28/2010 10/28/2015 Common Stock 0 $0.0 0 I by Spouse
Non-Qualified Stock Option (right to buy) $17.92 08/09/2013 M 941 12/28/2012 08/03/2014 Common Stock 941 $0.0 0 I by Spouse
Explanation of Responses:
1. In accordance with the reporting person's 10b5-1 trading plan.
2. On December 11, 2012, the Company's Board declared a special cash dividend of $1.00 per common share, which was paid on December 28, 2012 to all shareholders of record as of the close of business on December 21, 2012. The Board approved a modification whereby each outstanding option as of December 28, 2012 was increased by a ratio of 1.0471 with a corresponding reduction in the exercise price.
3. Equitable stock dividend adjustment approved by the Board of Director as a result of dividend Payment to shareholders on December 28, 2012. Stock dividends will release according to the same vesting schedule as the original grants.
4. Shares sold to pay tax obligations resulting from the vesting of restricted stock units.
By: Saria Tseng For: Deming Xiao 08/09/2013
** 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.
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