Sec Form 4 Filing - CARCHEDI FRANCIS @ COSTAR GROUP INC - 2017-02-28

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person CARCHEDI FRANCIS 2. Issuer Name and Ticker or Trading Symbol COSTAR GROUP INC [ CSGP] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Executive VP, Corp. Dev. (Last) (First) (Middle) C/O COSTAR GROUP, INC., 1331 L STREET, NW 3. Date of Earliest Transaction (MM/DD/YY) 02/28/2017 (Street) WASHINGTON, DC20005 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock, par value $0.01 per share 02/28/2017 F 630 D $ 203.99 23,366 ( 1 ) D Common Stock, par value $0.01 per share 03/02/2017 D 957 ( 2 ) D $ 0 22,409 ( 3 ) D Common Stock, par value $0.01 per share 03/02/2017 F 785 D $ 206.8 21,624 ( 4 ) D Common Stock, par value $0.01 per share 03/02/2017 A 7,380 ( 5 ) A $ 0 29,004 ( 6 ) D Common Stock, par value $0.01 per share 03/02/2017 M 4,500 A $ 37.42 33,504 ( 7 ) D Common Stock, par value $0.01 per share 03/02/2017 S 4,500 D $ 204.98 ( 8 ) 29,004 ( 6 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Option to Acquire Common Stock $ 204.91 03/02/2017 A 8,300 ( 9 ) 03/01/2027 Common Stock 8,300 $ 0 8,300 D Option to Acquire Common Stock $ 37.42 03/02/2017 M 4,500 ( 10 ) 07/15/2019 Common Stock 4,500 $ 0 5,500 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other CARCHEDI FRANCIS C/O COSTAR GROUP, INC. 1331 L STREET, NW WASHINGTON, DC20005 Executive VP, Corp. Dev. Signatures /s/ Jonathan Coleman, Attorney-in-Fact 03/02/2017 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents all shares of Common Stock owned, consisting of 7,052 shares of Common Stock and 16,314 shares of Common Stock subject to unvested Restricted Stock grants. ( 2 )Shares forfeited from February 28, 2014 performance restricted stock grant upon measurement and certification of achievement of the performance goal by the Compensation Committee. ( 3 )Represents all shares of Common Stock owned, consisting of 7,052 shares of Common Stock and 15,357 shares of Common Stock subject to unvested Restricted Stock grants. ( 4 )Represents all shares of Common Stock owned, consisting of 8,430 shares of Common Stock and 13,194 shares of Common Stock subject to unvested Restricted Stock grants. ( 5 )Includes a grant of 4,500 shares of restricted common stock that vest in three equal installments on March 2, 2018, March 2, 2019 and March 2, 2020, and a grant of 2,880 shares of restricted common stock that vest based upon CoStar Group, Inc.'s achievement of a three-year performance goal. ( 6 )Represents all shares of Common Stock owned, consisting of 8,430 shares of Common Stock and 20,574 shares of Common Stock subject to unvested Restricted Stock grants. ( 7 )Represents all shares of Common Stock owned, consisting of 12,930 shares of Common Stock and 20,574 shares of Common Stock subject to unvested Restricted Stock grants. ( 8 )Average based on sales prices ranging from $204.83 to $205.04. ( 9 )The option vests in three equal installments on March 2, 2018, March 2, 2019 and March 2, 2020. ( 10 )The option vested in four equal installments on July 16, 2010, July 16, 2011, July 16, 2012 and July 16, 2013.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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