[Form 4] CoStar Group Inc Insider Trading Activity

Rhea-AI Filing Summary

Angelique G. Brunner, a director of CoStar Group, Inc. (CSGP), acquired 3,143 shares of the company’s common stock on 09/09/2025 at no reported cash price, bringing her total beneficial ownership to 10,166 shares held directly. The Form 4 discloses this non-derivative purchase and indicates the filing was executed by an attorney-in-fact on behalf of the reporting person.

The filing shows a single, straightforward purchase of common stock by an insider rather than a sale or derivative transaction; no option grants, conversions, or other derivative activity are reported.

Positive

• Insider purchase disclosed: Director Angelique G. Brunner bought 3,143 shares, increasing direct ownership to 10,166 shares.
• No derivatives or sales reported: The filing shows a straightforward non-derivative acquisition, simplifying interpretation for investors.

Negative

• None.

Insights

Securities Analyst

TL;DR: Small director purchase increases direct ownership modestly; no derivatives or sales reported, so impact on valuation appears limited.

The acquisition of 3,143 shares by a company director is a clear insider purchase signal but, in isolation, represents a modest change in holdings (total beneficial ownership reported as 10,166 shares). There are no disposals or derivative positions disclosed, and the transaction is recorded as a non-derivative acquisition. Without context on total outstanding shares or prior holdings scale, this transaction is unlikely to be materially price-moving. Disclosure is complete for the reported class and follows Section 16 reporting conventions.

Corporate Governance Expert

TL;DR: Routine insider purchase by a director; governance disclosure appears standard and compliant.

The Form 4 shows the director increasing direct beneficial ownership through a non-derivative purchase. The report does not indicate any related-party arrangements, derivative instruments, or simultaneous disposals. From a governance perspective, timely disclosure of an insider acquisition supports transparency. The magnitude of the purchase relative to total insider holdings is small based on the numbers shown, suggesting limited governance or control implications.

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
Estimated average burden
hours per response:			0.5

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^*

Brunner Angelique G.

(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		3,143	A	$0	10,166	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 transaction did Angelique G. Brunner report on Form 4 for CSGP?

The Form 4 reports a non-derivative acquisition of 3,143 shares of CoStar Group common stock.

How many shares does Angelique G. Brunner beneficially own after the reported transaction?

The filing shows she beneficially owns 10,166 shares following the purchase.

Did the Form 4 report any derivative transactions or sales for CSGP?

No. The Form 4 discloses only a non-derivative acquisition; there are no derivative positions or dispositions reported.

Is the reported transaction by the director likely to be material to CSGP investors?

Based solely on the numbers in the filing, the acquisition appears modest and not materially impactful; no indication of a large, market-moving change is provided.