COSTAR GROUP, INC. — Director's Dealing 2013

Mar 13, 2013

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: COSTAR GROUP INC (CSGP)
CIK: 0001057352
Period of Report: 2013-03-11

Reporting Person: Radecki Brian J (Chief Financial Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-03-11	Common Stock, par value $0.01 per share	A	8100	—	Acquired	71936	Direct
2013-03-12	Common Stock, par value $0.01 per share	F	1265	$101.06	Disposed	70671	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-03-11	Option to Acquire Common Stock	$102.16	A	13500	Acquired	2023-03-10	Common Stock (13500)	Direct

Footnotes

F1: Represents all shares of Common Stock owned, consisting of 18,635 shares of Common Stock and 53,301 shares of Common Stock subject to unvested Restricted Stock Grants.

F2: 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.

F3: The option vests in three equal installments on March 11, 2014, March 11, 2015, and March 11, 2016.