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: Stanfill John L (Sr. VP-Sales, Customer Service)

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	6000	—	Acquired	50184	Direct
2013-03-12	Common Stock, par value $0.01 per share	M	2300	$42.29	Acquired	52484	Direct
2013-03-12	Common Stock, par value $0.01 per share	M	3900	$57.16	Acquired	56384	Direct
2013-03-12	Common Stock, par value $0.01 per share	M	196	$39.53	Acquired	56580	Direct
2013-03-12	Common Stock, par value $0.01 per share	M	3866	$58.95	Acquired	60446	Direct
2013-03-12	Common Stock, par value $0.01 per share	S	14599	$101.10	Disposed	45847	Direct
2013-03-12	Common Stock, par value $0.01 per share	F	486	$101.06	Disposed	45361	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	10100	Acquired	2023-03-10	Common Stock (10100)	Direct
2013-03-12	Option to Acquire Common Stock	$42.29	M	2300	Disposed	2020-03-11	Common Stock (2300)	Direct
2013-03-12	Option to Acquire Common Stock	$57.16	M	3900	Disposed	2021-03-03	Common Stock (3900)	Direct
2013-03-12	Option to Acquire Common Stock	$39.53	M	196	Disposed	2014-05-04	Common Stock (196)	Direct
2013-03-12	Option to Acquire Common Stock	$58.95	M	3866	Disposed	2022-02-20	Common Stock (3866)	Direct

Footnotes

F1: Represents all shares of Common Stock owned, consisting of 5,449 shares of Common Stock and 44,735 shares of Common Stock subject to unvested Restricted Stock Grants.

F2: Represents all shares of Common Stock owned, consisting of 7,749 shares of Common Stock and 44,735 shares of Common Stock subject to unvested Restricted Stock Grants.

F3: Represents all shares of Common Stock owned, consisting of 11,649 shares of Common Stock and 44,735 shares of Common Stock subject to unvested Restricted Stock Grants.

F4: Represents all shares of Common Stock owned, consisting of 11,845 shares of Common Stock and 44,735 shares of Common Stock subject to unvested Restricted Stock Grants.

F5: Represents all shares of Common Stock owned, consisting of 15,711 shares of Common Stock and 44,735 shares of Common Stock subject to unvested Restricted Stock Grants.

F6: Average based on sales prices ranging from $100.75 to $102.35.

F7: Represents all shares of Common Stock owned, consisting of 1,112 shares of Common Stock and 44,735 shares of Common Stock subject to unvested Restricted Stock Grants.

F8: Represents all shares of Common Stock owned, consisting of 1,660 shares of Common Stock and 43,701 shares of Common Stock subject to unvested Restricted Stock Grants.

F9: The option vests in three equal installments on March 11, 2014, March 11, 2015, and March 11, 2016.

F10: The option vested in three equal installments on March 12, 2011, March 12, 2012, and March 12, 2013.

F11: The option vests in three equal installments on March 4, 2012, March 4, 2013, and March 4, 2014.

F12: The option vested in three equal installments on May 5, 2005, May 5, 2006, May 5, 2007, and May 5, 2008.

F13: The option vests in three equal installments on February 21, 2013, February 21, 2014, and February 21, 2015.