Sec Form 4 Filing - Wheeler Scott T @ COSTAR GROUP, INC. - 2021-03-15

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 Wheeler Scott T 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) Chief Financial Officer (Last) (First) (Middle) C/O COSTAR GROUP, INC., 1331 L STREET NW 3. Date of Earliest Transaction (MM/DD/YY) 03/15/2021 (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 03/15/2021 A 1,598 A 29,006 ( 2 ) D Common Stock, par value $0.01 per share 03/16/2021 M 3,600 A $ 342.13 32,606 ( 3 ) D Common Stock, par value $0.01 per share 03/16/2021 M 2,133 A $ 398.15 34,739 ( 4 ) D Common Stock, par value $0.01 per share 03/16/2021 S 7,326 D $ 843.28 ( 5 ) 27,413 ( 6 ) D Common Stock, par value $0.01 per share 03/16/2021 G V 265 D $ 0 27,148 ( 7 ) D Common Stock, par value $0.01 per share 03/08/2021 G V 111 D $ 0 27,037 ( 8 ) D Common Stock, par value $0.01 per share 03/08/2021 G V 37 A $ 0 73 I By Abraham James Wheeler Trust ( 9 ) Common Stock, par value $0.01 per share 03/08/2021 G V 37 A $ 0 73 I By Anna Karin Wheeler Trust ( 10 ) Common Stock, par value $0.01 per share 03/08/2021 G V 37 A $ 0 73 I By Jacob Paul Wheeler Trust ( 11 )

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 $ 342.13 03/16/2021 M 3,600 ( 12 ) 02/27/2028 Common Stock 3,600 $ 0 0 D Option to Acquire Common Stock $ 398.15 03/16/2021 M 2,133 ( 13 ) 02/06/2029 Common Stock 2,133 $ 0 4,267 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Wheeler Scott T C/O COSTAR GROUP, INC. 1331 L STREET NW WASHINGTON, DC20005 Chief Financial Officer Signatures /s/ Jeannette Koonce, Attorney-in-Fact 03/17/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Pursuant to the Management Stock Purchase Plan, all or a portion of the reporting person's annual cash incentive amount was converted to Deferred Stock Units (each equivalent to one share of common stock) at $837.86 per unit, and the Company awarded the reporting person Restricted Stock Units that vest in full after four years for an equal number of shares of common stock. ( 2 )Represents all shares of Common Stock owned, consisting of 5,009 shares of Common Stock, 18,221 shares of Common Stock subject to unvested Restricted Stock grants, 2,888 shares of Deferred Stock Units and 2,888 shares of unvested Restricted Stock Units. ( 3 )Represents all shares of Common Stock owned, consisting of 8,609 shares of Common Stock, 18,221 shares of Common Stock subject to unvested Restricted Stock grants, 2,888 shares of Deferred Stock Units and 2,888 shares of unvested Restricted Stock Units. ( 4 )Represents all shares of Common Stock owned, consisting of 10,742 shares of Common Stock, 18,221 shares of Common Stock subject to unvested Restricted Stock grants, 2,888 shares of Deferred Stock Units and 2,888 shares of unvested Restricted Stock Units. ( 5 )Average based on sales prices ranging from $840.55 to $846.07. ( 6 )Represents all shares of Common Stock owned, consisting of 3,416 shares of Common Stock, 18,221 shares of Common Stock subject to unvested Restricted Stock grants, 2,888 shares of Deferred Stock Units and 2,888 shares of unvested Restricted Stock Units. ( 7 )Represents all shares of Common Stock owned, consisting of 3,151 shares of Common Stock, 18,221 shares of Common Stock subject to unvested Restricted Stock grants, 2,888 shares of Deferred Stock Units and 2,888 shares of unvested Restricted Stock Units. ( 8 )Represents all shares of Common Stock owned, consisting of 3,040 shares of Common Stock, 18,221 shares of Common Stock subject to unvested Restricted Stock grants, 2,888 shares of Deferred Stock Units and 2,888 shares of unvested Restricted Stock Units. ( 9 )Of the shares gifted by reporting person on March 8, 2021, 37 were irrevocably gifted to the Abraham James Wheeler Trust for the benefit of the reporting person's son. The reporting person disclaims beneficial ownership of the securities held by the trust except to the extent of his pecuniary interest therein. ( 10 )Of the shares gifted by reporting person on March 8, 2021, 37 were irrevocably gifted to the Anna Karin Wheeler Trust for the benefit of the reporting person's daughter. The reporting person disclaims beneficial ownership of the securities held by the trust except to the extent of his pecuniary interest therein. ( 11 )Of the shares gifted by reporting person on March 8, 2021, 37 were irrevocably gifted to the Jacob Paul Wheeler Trust for the benefit of the reporting person's son. The reporting person disclaims beneficial ownership of the securities held by the trust except to the extent of his pecuniary interest therein. ( 12 )The option vested in three equal installments on February 28, 2019, February 29, 2020 and February 28, 2021. ( 13 )The option vests in three equal installments on February 15, 2020, February 15, 2021 and February 15, 2022.

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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