Sec Form 4 Filing - Sciammas Maurice @ MONOLITHIC POWER SYSTEMS INC - 2013-12-14

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Sciammas Maurice 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) Sr. V.P.of Sales and Marketing (Last) (First) (Middle) 79 GREAT OAKS BLVD 3. Date of Earliest Transaction (MM/DD/YY) 12/14/2013 (Street) SAN JOSE, CA95119 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 07/22/2014( 1 ) M( 1 ) 43,200 ( 1 ) A $ 0 129,525 D Common Stock 10/21/2014( 2 ) M( 2 ) 43,200 ( 2 ) A $ 0 167,748 D Common Stock 11/21/2014 S( 3 ) 7,086 D $ 46.4214 ( 4 ) 156,029 D Common Stock 11/21/2014 M 10,000 A $ 15.03 ( 5 ) 166,029 D Common Stock 11/21/2014 S( 3 ) 10,000 D $ 46.2492 ( 6 ) 156,029 D Common Stock 2,000 I by Family Trust

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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) $ 15.74 ( 5 ) 11/21/2014 M 10,000 10/28/2010 10/28/2015 Common Stock 10,000 $ 0 0 D Performance Shares ( 7 ) ( 8 ) 12/14/2013 A( 9 ) 216,000 ( 7 ) ( 8 ) ( 8 ) Common Stock 216,000 ( 9 ) $ 0 216,000 ( 9 ) D Performance Shares ( 8 ) 07/22/2014( 1 ) M( 1 ) 43,200 ( 1 ) ( 8 ) ( 8 ) Common Stock 43,200 $ 0 172,800 D Performance Shares ( 8 ) 10/21/2014( 2 ) M( 2 ) 43,200 ( 2 ) ( 8 ) ( 8 ) Common Stock 43,200 $ 0 129,600 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Sciammas Maurice 79 GREAT OAKS BLVD SAN JOSE, CA95119 Sr. V.P.of Sales and Marketing Signatures By: Saria Tseng For: Maurice Sciammas 11/21/2014 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each performance share represents a contingent right to receive a restricted stock unit upon MPWR's common stock achieving a 20-day average closing price of $40.00 per share from January 1, 2014 through December 31, 2018 (the "Performance Period"). Credited performance units are still subject to an additional, quarterly, five-year time-based vesting schedule beginning January 1, 2019, subject to acceleration under certain circumstances. ( 2 )Each performance share represents a contingent right to receive a restricted stock unit upon MPWR's common stock achieving a 20-day average closing price of $43.00 per share from January 1, 2014 through December 31, 2018 (the "Performance Period"). Credited performance units are still subject to an additional, quarterly, five-year time-based vesting schedule beginning January 1, 2019, subject to acceleration under certain circumstances. ( 3 )Transaction was executed during an authorized trading window in compliance with the Company's Insider Trading Compliance Program. ( 4 )The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $46.4201 to $46.51. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price. ( 5 )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. ( 6 )The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $46.19 to $46.38. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price. ( 7 )The reporting person was granted 43,200 performance units on December 14, 2013. Each performance unit vests as stated: one share of MPWR common stock will be credited for each performance unit if the price of MPWR common stock achieves a 20-day average closing price of $40.00 per share from January 1, 2014 through December 31, 2018 (the "Performance Period"), and up to four additional shares will be credited for each performance unit if the 20-day average closing price reaches $43.00, $47.00, $52.00, and $56.00 (one share per price level) during the Performance Period. Credited performance units are subject to an additional, five-year, quarterly, time-based vesting schedule beginning January 1, 2019, subject to acceleration under certain circumstances. The derivative securities reported in columns 5 and 9 reflect the maximum payout achievable. If the Company does not achieve a price threshold within the Performance Period, 1/5 of the reported derivative securities will be forfeited. ( 8 )Each performance unit will vest as follows: one share of MPWR common stock will be credited for each performance unit if the price of MPWR common stock achieves a 20-day average closing price of $40.00 per share from January 1, 2014 through December 31, 2018 (the "Performance Period"), and up to four additional shares will be credited for each performance unit if the 20-day average closing price reaches $43.00, $47.00, $52.00 and $56.00 (that is, one share per price level) during the Performa nce Period. Credited performance units are then subject to an additional, quarterly, five-year time-based vesting schedule beginning January 1, 2019, subject to acceleration under certain circumstances. ( 9 )No new grants are being reported by this amendment. This amendment merely increases the number of derivative securities originally reported in column 5 and 9 of Table II of the Form 4 filed with the SEC on December 18, 2013 to match the number of shares underlying the derivative security originally reported in column 7 of Table II. These changes are needed to allow the Company to utilize its existing Section 16 filing program to report the vesting of the performance units when the different price thresholds are achieved. The Company's existing filing program does not allow for the reporting of vesting of performance units that entitle a grantee to a potential payout under those units greater than 1x.

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