[Form 4] CoStar Group Inc Insider Trading Activity

Rhea-AI Filing Summary

Christine M. McCarthy, a director of CoStar Group, Inc. (CSGP), reported a purchase of 2,973 shares of the company's common stock on 09/09/2025 at a reported price of $0, resulting in direct beneficial ownership of 2,973 shares following the transaction. The Form 4 was signed by an attorney-in-fact on 09/11/2025. The filing documents an insider acquisition by a board member but does not disclose reason or additional holdings.

Insights

Corporate Governance Expert

TL;DR: A director-reported acquisition of a small number of shares, documented and timely filed; not material to control or governance.

The Form 4 shows a director, Christine M. McCarthy, acquiring 2,973 shares directly. The transaction was reported with a $0 price, which the filing does not explain, and was signed by an attorney-in-fact. For governance purposes this is a routine insider purchase disclosure that demonstrates compliance with Section 16 reporting requirements. The size of the holding is small relative to typical public-company equity stakes and does not indicate a change in control or board alignment.

Securities Analyst

TL;DR: Insider acquisition disclosed; transaction size is immaterial to valuation or market dynamics.

The reported acquisition of 2,973 shares at a reported price of $0 is documented on Form 4. Absent further detail on the $0 price (gift, exercise, error, or administrative transfer), there is no clear market-price signal. The post-transaction direct ownership equals the shares acquired, implying no prior reported position in this filing. This disclosure is informative for transparency but unlikely to affect short-term valuation or trading given its small absolute size.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

McCarthy Christine M

(Last) (First) (Middle)

C/O COSTAR GROUP, INC.

1201 WILSON BLVD.

(Street)

ARLINGTON VA 22209

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
COSTAR GROUP, INC. [ CSGP ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
09/09/2025

4. If Amendment, Date of 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

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	09/09/2025		A		2,973	A	$0	2,973	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 (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 Securities Underlying Derivative Security (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: 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

Explanation of Responses:

Remarks:

	/s/ Gene Boxer, Attorney-in-Fact	09/11/2025
	** Signature of Reporting Person	Date
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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did Christine M. McCarthy report on Form 4 for CSGP?

She reported a direct acquisition of 2,973 shares of CoStar Group common stock on 09/09/2025, with 2,973 shares owned after the transaction.

What price was reported for the insider purchase on the Form 4 (CSGP)?

The reported price is $0 on the Form 4 filing; the document does not provide an explanation for the $0 price.

When was the Form 4 for CSGP signed and filed?

The Form 4 shows an attorney-in-fact signature dated 09/11/2025; the transaction date is 09/09/2025.

Does this Form 4 indicate a material change in ownership for CSGP?

No. The reported acquisition of 2,973 shares is small and the filing contains no indication of a material change in control or ownership stake.

What is the reporting person’s role at CoStar Group (CSGP)?

Christine M. McCarthy is identified as a Director of CoStar Group on the Form 4.