COSTAR GROUP, INC. — Director's Dealing 2011

Jun 22, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: COSTAR GROUP INC (CSGP)
CIK: 0001057352
Period of Report: 2011-06-21

Reporting Person: KLEIN MICHAEL R (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-06-21	Common Stock, par value $0.01 per share	M	3000	$17.97	Acquired	413675	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-06-21	Option to Acquire Common Stock	$17.97	M	3000	Disposed	2011-09-27	Common Stock (3000)	Direct

Footnotes

F1: Represents all shares of Common Stock owned, consisting of 409,549 shares of Common Stock and 4,126 shares of Common Stock subject to unvested Restricted Stock Grants.

F2: The option vested in four equal installments on September 28, 2002, September 28, 2003, September 28, 2004 and September 28, 2005.