Sec Form 4 Filing - Linnington Matthew @ COSTAR GROUP, INC. - 2019-07-31

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 Linnington Matthew 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, Sales (Last) (First) (Middle) C/O COSTAR GROUP, INC., 1331 L STREET, NW 3. Date of Earliest Transaction (MM/DD/YY) 07/31/2019 (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 07/31/2019 M 3,500 A $ 182.75 26,923 ( 1 ) D Common Stock, par value $0.01 per share 07/31/2019 M 7,533 A $ 204.91 34,456 ( 2 ) D Common Stock, par value $0.01 per share 07/31/2019 M 2,000 A $ 342.13 36,456 ( 3 ) D Common Stock, par value $0.01 per share 07/31/2019 S 14,651 D $ 617.39 ( 4 ) 21,805 ( 5 ) 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 $ 182.75 07/31/2019 M 3,500 ( 6 ) 03/10/2026 Common Stock 3,500 $ 0 0 D Option to Acquire Common Stock $ 204.91 07/31/2019 M 7,533 ( 7 ) 03/01/2027 Common Stock 7,533 $ 0 3,767 D Option to Acquire Common Stock $ 342.13 07/31/2019 M 2,000 ( 8 ) 02/27/2028 Common Stock 2,000 $ 0 4,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Linnington Matthew C/O COSTAR GROUP, INC. 1331 L STREET, NW WASHINGTON, DC20005 Executive VP, Sales Signatures /s/ Jonathan Coleman, Attorney-in-Fact 08/01/2019 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents all shares of Common Stock owned, consisting of 11,449 shares of Common Stock and 15,474 shares of Common Stock subject to unvested Restricted Stock grants. ( 2 )Represents all shares of Common Stock owned, consisting of 18,982 shares of Common Stock and 15,474 shares of Common Stock subject to unvested Restricted Stock grants. ( 3 )Represents all shares of Common Stock owned, consisting of 20,982 shares of Common Stock and 15,474 shares of Common Stock subject to unvested Restricted Stock grants. ( 4 )Average based on sales prices ranging from $617 to $618.13. ( 5 )Represents all shares of Common Stock owned, consisting of 6,331 shares of Common Stock and 15,474 shares of Common Stock subject to unvested Restricted Stock grants. ( 6 )The option vested in three equal installments on March 11, 2017, March 11, 2018 and March 11, 2019. ( 7 )The option vests in three equal installments on March 31, 2018, March 31, 2019 and March 31, 2020. ( 8 )The option vests in three equal installments on February 28, 2019, February 28, 2020 and February 28, 2021.

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).

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