CoStar (CSGP) director amends Form 3 to show 350 shares held

Rhea-AI Filing Summary

CoStar Group director Christine M. McCarthy filed an amended initial ownership report to correct her disclosed holdings. The amendment shows she directly holds 350 shares of Common Stock, par value $0.01 per share. A footnote explains these shares were omitted from her original Form 3 and from one subsequent Form 4.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider McCarthy Christine M

Role Director

Type	Security	Shares	Price	Value
holding	Common Stock, par value $0.01 per share	--	--	--

Holdings After Transaction: Common Stock, par value $0.01 per share — 350 shares (Direct)

Footnotes (1)

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Key Figures

Directly held shares: 350 shares

1 metrics

Directly held shares 350 shares Common Stock, par value $0.01 per share, after amendment

Key Terms

Form 3, Form 4, Common Stock, par value $0.01 per share, reporting person

4 terms

Form 3 regulatory

"These shares were omitted from the reporting person's original Form 3"

Form 3 is the initial public filing that officers, directors and large shareholders must submit to report their ownership of a company’s securities when they become insiders. It acts like an opening inventory sheet that gives investors a starting point to see who holds significant stakes and to spot later trades or potential conflicts of interest, helping assess insider confidence and transparency.

Form 4 regulatory

"and also were omitted from one Form 4 filed by the reporting person"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

Common Stock, par value $0.01 per share financial

"security_title: Common Stock, par value $0.01 per share"

reporting person regulatory

"These shares were omitted from the reporting person's original Form 3"

Understanding Insider Trading Forms →

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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:			3235-0104
Estimated average burden
hours per response:			0.5

1. Name and Address of Reporting Person^*

McCarthy Christine M

(Last) (First) (Middle)

C/O COSTAR GROUP, INC.

1201 WILSON BLVD.

(Street)

ARLINGTON VIRGINIA 22209

(City) (State) (Zip)

UNITED STATES

(Country)

2. Date of Event Requiring Statement (Month/Day/Year)
03/25/2025

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

3a. Foreign Trading Symbol

5. If Amendment, Date of Original Filed (Month/Day/Year)
04/06/2025

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

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

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	350(1)	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: 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

Explanation of Responses:

1. These shares were omitted from the reporting person's original Form 3, and also were omitted from one Form 4 filed by the reporting person after her original Form 3 was filed.

Remarks:

	/s/ Gene Boxer, Attorney-in-Fact	04/02/2026
	** 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 5 (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.
* Form 3: SEC 1473 (03-26)

FAQ

What does the CoStar (CSGP) Form 3/A filing for Christine M. McCarthy report?

The Form 3/A shows director Christine M. McCarthy directly holds 350 shares of CoStar Group Common Stock. The amendment corrects her original Form 3, which had omitted these shares, and also updates one later Form 4 that likewise did not include them.

Why did Christine M. McCarthy amend her Form 3 with CoStar (CSGP)?

She amended her Form 3 because 350 shares of Common Stock were mistakenly omitted from her original filing. A footnote states these shares were also omitted from one Form 4 filed after the original Form 3, so the amendment updates her reported holdings.

How many CoStar (CSGP) shares does Christine M. McCarthy now report holding?

She now reports direct ownership of 350 shares of CoStar Group Common Stock. This figure reflects shares that were previously left out of her original Form 3 and one subsequent Form 4, aligning her reported holdings with her actual ownership position.

Does the CoStar (CSGP) Form 3/A show any new buy or sell transactions?

The Form 3/A does not report any new buy or sell transactions. It provides a holding entry showing 350 shares owned directly and clarifies via footnote that these shares were previously omitted, rather than recently acquired or disposed of in the market.

What role does Christine M. McCarthy hold at CoStar (CSGP) in this Form 3/A?

In this Form 3/A, Christine M. McCarthy is identified as a director of CoStar Group, Inc. The filing focuses on correcting her reported Common Stock holdings, ensuring her director ownership disclosure accurately reflects 350 directly held shares.