COSTAR GROUP, INC. — Director's Dealing 2013

Aug 6, 2013

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: COSTAR GROUP INC (CSGP)
CIK: 0001057352
Period of Report: 2013-08-02

Reporting Person: NASSETTA CHRISTOPHER J (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-08-02	Common Stock, par value $0.01 per share	M	1800	$30.06	Acquired	19786	Direct
2013-08-02	Common Stock, par value $0.01 per share	S	1800	$158.71	Disposed	17986	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-08-02	Option to Acquire Common Stock	$30.06	M	1800	Disposed	2013-09-03	Common Stock (1800)	Direct

Footnotes

F1: Represents all shares of Common Stock owned, consisting of 15,849 shares of Common Stock and 3,937 shares of Common Stock subject to unvested Restricted Stock Grants.

F2: Average based on sales prices ranging from $158.69 to $158.89.

F3: Represents all shares of Common Stock owned, consisting of 14,049 shares of Common Stock and 3,937 shares of Common Stock subject to unvested Restricted Stock Grants.

F4: The option vested in four equal installments on September 4, 2004, September 4, 2005, September 4, 2006 and September 4, 2007.