COSTAR GROUP, INC. — Director's Dealing 2011

Mar 14, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: COSTAR GROUP INC (CSGP)
CIK: 0001057352
Period of Report: 2011-03-12

Reporting Person: FLORANCE ANDREW C (Director, President and CEO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-03-12	Common Stock, par value $0.01 per share	F	2399	$56.21	Disposed	207559	Direct

Footnotes

F1: Represents all shares of Common Stock owned, consisting of 166,374 shares of Common Stock and 41,185 shares of Common Stock subject to unvested Restricted Stock Grants. As a result of an inadvertent error in calculating the number of shares withheld for taxes on restricted stock that vested on March 2, 2011, the number of shares reported as withheld for taxes was over-reported on the filer's Form 4 filed on March 4, 2011, and the filer's Forms 4 filed on March 4, 2011 and March 8, 2011 under-reported the total shares beneficially owned by the filer by 16 shares. Column 5 of this Form 4 includes those 16 shares and reflects the corrected amount.