Ownership Submission
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 OF SECURITIES

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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(Print or Type Responses)
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 (Month/Day/Year)
07/27/2018
(Street)

WASHINGTON, DC 20005		 4. If Amendment, Date Original Filed(Month/Day/Year)
 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 (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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 07/27/2018   M   11,100 A $ 201.04 38,300 (1) D  
Common Stock, par value $0.01 per share 07/27/2018   M   7,468 A $ 193.69 45,768 (2) D  
Common Stock, par value $0.01 per share 07/27/2018   M   5,466 A $ 182.75 51,234 (3) D  
Common Stock, par value $0.01 per share 07/27/2018   M   2,766 A $ 204.91 54,000 (4) D  
Common Stock, par value $0.01 per share 07/27/2018   S   32,671 D $ 421.87 (5) 21,329 (6) D  
Common Stock, par value $0.01 per share 07/27/2018   M   1,032 A $ 193.69 22,361 (7) D  
Common Stock, par value $0.01 per share 07/27/2018   F   474 D $ 421.8 21,887 (8) D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 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
(Month/Day/Year)		 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 $ 201.04 07/27/2018   M     11,100   (9) 02/27/2024 Common Stock 11,100 $ 0 0 D  
Option to Acquire Common Stock $ 193.69 07/27/2018   M     7,468   (10) 03/04/2025 Common Stock 7,468 $ 0 1,032 D  
Option to Acquire Common Stock $ 182.75 07/27/2018   M     5,466   (11) 03/10/2026 Common Stock 5,466 $ 0 2,734 D  
Option to Acquire Common Stock $ 204.91 07/27/2018   M     2,766   (12) 03/01/2027 Common Stock 2,766 $ 0 5,534 D  
Option to Acquire Common Stock $ 193.69 07/27/2018   M     1,032   (10) 03/04/2025 Common Stock 1,032 $ 0 0 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, DC 20005		       Executive VP, Corp. Dev.  

Signatures

 /s/ Jonathan Coleman, Attorney-in-Fact   07/31/2018
**Signature of Reporting Person Date

Explanation of Responses:

* 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).
(1) Represents all shares of Common Stock owned, consisting of 22,953 shares of Common Stock and 15,347 shares of Common Stock subject to unvested Restricted Stock grants.
(2) Represents all shares of Common Stock owned, consisting of 30,421 shares of Common Stock and 15,347 shares of Common Stock subject to unvested Restricted Stock grants.
(3) Represents all shares of Common Stock owned, consisting of 35,887 shares of Common Stock and 15,347 shares of Common Stock subject to unvested Restricted Stock grants.
(4) Represents all shares of Common Stock owned, consisting of 38,653 shares of Common Stock and 15,347 shares of Common Stock subject to unvested Restricted Stock grants.
(5) Average based on sales prices ranging from $418.66 to $433.92.
(6) Represents all shares of Common Stock owned, consisting of 5,982 shares of Common Stock and 15,347 shares of Common Stock subject to unvested Restricted Stock grants.
(7) Represents all shares of Common Stock owned, consisting of 7,014 shares of Common Stock and 15,347 shares of Common Stock subject to unvested Restricted Stock grants.
(8) Represents all shares of Common Stock owned, consisting of 6,540 shares of Common Stock and 15,347 shares of Common Stock subject to unvested Restricted Stock grants.
(9) The option vested in three equal installments on February 28, 2015, February 28, 2016, and February 28, 2017.
(10) The option vested in three equal installments on March 5, 2016, March 5, 2017 and March 5, 2018.
(11) The option vests in three equal installments on March 11, 2017, March 11, 2018 and March 11, 2019.
(12) The option vests in three equal installments on March 31, 2018, March 31, 2019 and March 31, 2020.

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