MONOLITHIC POWER SYSTEMS INC — Director's Dealing 2015

May 11, 2015

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MONOLITHIC POWER SYSTEMS INC (MPWR)
CIK: 0001280452
Period of Report: 2015-05-07

Reporting Person: Xiao Deming (Pres. of MPS Asia Operations)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2015-05-07	Common Stock	S	2000.0	$51.966	Disposed	254483	Direct
2015-05-07	Common Stock	S	2779.0	$51.7857	Disposed	251704	Direct
2015-05-08	Common Stock	S	1852.0	$51.79	Disposed	249852	Direct
2015-05-08	Common Stock	S	88.0	$51.79	Disposed	249764	Direct
2015-05-08	Common Stock	S	1744.0	$52.5201	Disposed	248020	Direct
2015-05-11	Common Stock	S	1757.0	$52.408	Disposed	246263	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	1667	Indirect

Footnotes

F1: 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 $51.90 to $52.07. 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.

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 $51.76 to $51.79. 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.

F3: Shares sold to pay tax obligations resulting from the vesting of restricted stock units.