Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * SAINT FREDERICK G.	2. Date of Event Requiring Statement (MM/DD/YYYY) 9/24/2020	3. Issuer Name and Ticker or Trading Symbol COSTAR GROUP, INC. [CSGP]
(Last)        (First)        (Middle) C/O COSTAR GROUP, INC., 1331 L STREET NW	4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                          _____ 10% Owner ___X___ Officer (give title below)        _____ Other (specify below) President, Marketplaces /
(Street) WASHINGTON, DC 20005       (City)              (State)              (Zip)	5. If Amendment, Date Original Filed(MM/DD/YYYY)	6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock, par value $0.01 per share	22076 (1)	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Option to Acquire Common Stock	(2)	3/1/2027	Common Stock	2767.0	$204.91	D
Option to Acquire Common Stock	(3)	2/27/2028	Common Stock	5067.0	$342.13	D
Option to Acquire Common Stock	(4)	2/6/2029	Common Stock	4500.0	$398.15	D
Option to Acquire Common Stock	(5)	2/5/2030	Common Stock	3300.0	$666.52	D

Explanation of Responses:
(1)	Represents all shares of Common Stock owned, consisting of 5,903 shares of Common Stock and 13,727 shares of Common Stock subject to unvested Restricted Stock grants, 1,223 shares of Deferred Stock Units and 1,223 shares of unvested Restricted Stock Units.
(2)	The option vested in three equal installments on March 31, 2018, March 31, 2019 and March 31, 2020.
(3)	The option vests in three equal installments on February 28, 2019, February 28, 2020 and February 28, 2021.
(4)	The option vests in three equal installments on February 15, 2020, February 15, 2021 and February 15, 2022.
(5)	The option vests in three equal installments on February 15, 2021, February 15, 2022 and February 15, 2023.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
SAINT FREDERICK G. C/O COSTAR GROUP, INC. 1331 L STREET NW WASHINGTON, DC 20005			President, Marketplaces

Signatures
/s/ Jeannette Koonce, Attorney-in-Fact		10/5/2020
**Signature of Reporting Person		Date