COSTAR GROUP, INC. — Director's Dealing 2013

Aug 1, 2013

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: COSTAR GROUP INC (CSGP)
CIK: 0001057352
Period of Report: 2013-07-30

Reporting Person: Radecki Brian J (Chief Financial Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-07-30	Common Stock, par value $0.01 per share	M	4633	$58.95	Acquired	75304	Direct
2013-07-30	Common Stock, par value $0.01 per share	M	5634	$42.29	Acquired	80938	Direct
2013-07-30	Common Stock, par value $0.01 per share	S	10267	$157.00	Disposed	70671	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-07-30	Option to Acquire Common Stock	$58.95	M	4633	Disposed	2022-02-20	Common Stock (4633)	Direct
2013-07-30	Option to Acquire Common Stock	$42.29	M	5634	Disposed	2020-03-11	Common Stock (5634)	Direct

Footnotes

F1: Represents all shares of Common Stock owned, consisting of 24,537 shares of Common Stock and 50,767 shares of Common Stock subject to unvested Restricted Stock Grants.

F2: Represents all shares of Common Stock owned, consisting of 30,171 shares of Common Stock and 50,767 shares of Common Stock subject to unvested Restricted Stock Grants.

F3: Represents all shares of Common Stock owned, consisting of 19,904 shares of Common Stock and 50,767 shares of Common Stock subject to unvested Restricted Stock Grants.

F4: The option vests in three equal installments on February 21, 2013, February 21, 2014 and February 21, 2015.

F5: The option vested in three equal installments on March 12, 2011, March 12, 2012 and March 12, 2013.