COSTAR GROUP, INC. — Director's Dealing 2017

May 3, 2017

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: COSTAR GROUP INC (CSGP)
CIK: 0001057352
Period of Report: 2017-05-02

Reporting Person: CARCHEDI FRANCIS (Executive VP, Corp. Dev.)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-05-02	Common Stock, par value $0.01 per share	M	5500	$37.42	Acquired	30513	Direct
2017-05-02	Common Stock, par value $0.01 per share	S	5500	$245.04	Disposed	25013	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2017-05-02	Option to Acquire Common Stock	$37.42	M	5500	Disposed	2019-07-15	Common Stock (5500.0)	Direct

Footnotes

F1: Represents all shares of Common Stock owned, consisting of 12,972 shares of Common Stock and 17,541 shares of Common Stock subject to unvested Restricted Stock grants.

F2: Average based on sales prices ranging from $245.21 to $244.76.

F3: Represents all shares of Common Stock owned, consisting of 7,472 shares of Common Stock and 17,541 shares of Common Stock subject to unvested Restricted Stock grants.

F4: The option vested in four equal installments on July 16, 2010, July 16, 2011, July 16, 2012 and July 16, 2013.