COSTAR GROUP, INC. — Director's Dealing 2010

Mar 16, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: COSTAR GROUP INC (CSGP)
CIK: 0001057352
Period of Report: 2010-03-12

Reporting Person: Kitchen Jennifer (Sr. Vice President, Research)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-03-12	Common Stock, par value $0.01 per share	A	3500	—	Acquired	13816	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-03-12	Option to Acquire Common Stock	$42.29	A	7700	Acquired	2020-03-11	Common Stock (7700)	Direct

Footnotes

F1: Represents all shares of Common Stock owned, consisting of 2,973 shares of Common Stock and 10,843 shares of Common Stock subject to unvested Restricted Stock Grants. The reporting person was issued 39 shares of Common Stock on Saturday, October 3, 2009, as a service award from the issuer for her fifteen-year anniversary of employment. On the trading day immediately preceding the date of grant, the closing stock price of the Company's common stock was $39.45. The 39 shares were inadvertantly omitted from previous filings, but are included in the current total of shares directly held.

F2: The option vests in three equal installments on March 12, 2011, March 12, 2012, and March 12, 2013.