MONOLITHIC POWER SYSTEMS INC — Director's Dealing 2013

May 31, 2013

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MONOLITHIC POWER SYSTEMS INC (MPWR)
CIK: 0001280452
Period of Report: 2013-05-29

Reporting Person: Lee Victor K (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-05-29	Common Stock	M	5000.0	$9.24	Acquired	19589	Direct
2013-05-29	Common Stock	S	5000.0	$24.35	Disposed	14589	Direct
2013-05-30	Common Stock	M	5705.0	$9.24	Acquired	20294	Direct
2013-05-30	Common Stock	S	5705.0	$24.5013	Disposed	14589	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-05-29	Non-Qualified Stock Option (right to buy)	$9.24	M	5000.0	Disposed	2013-09-14	Common Stock (5000)	Direct
2013-05-30	Non-Qualified Stock Option (right to buy)	$9.24	M	5705.0	Disposed	2013-09-14	Common Stock (5705)	Direct

Footnotes

F1: Option shares will expire if not exercised on or before September 14, 2013.

F2: 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 $24.50 to $24.525. 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.