CoStar Group (CSGP) GC reports 482-share tax-withholding correction

Rhea-AI Filing Summary

CoStar Group’s General Counsel and Secretary, Gene Boxer, reported a small tax-related share disposition. On this amended Form 4, 482 shares of common stock were withheld at a price of $43.63 per share to cover tax obligations. After this non‑market, tax-withholding transaction, Boxer directly holds 95,463 shares of CoStar Group common stock. A footnote states that the reported amount reflects a correction due to an administrative error, indicating this filing primarily updates prior data rather than reflecting a new trading decision.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Boxer Gene

Role General Counsel and Secretary

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock, par value $0.01 per share	482	$43.63	$21K

Holdings After Transaction: Common Stock, par value $0.01 per share — 95,463 shares (Direct)

Footnotes (1)

1. This amount reflects a correction due to administrative error. On March 13, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $43.63.

Form 4 Insider Transactions: What Each Field Means →

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^*

Boxer Gene

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	General Counsel and Secretary

3. Date of Earliest Transaction (Month/Day/Year)
03/15/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)
03/17/2026

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	03/15/2026		F		482(1)	D	$43.63(2)	95,463	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:

1. This amount reflects a correction due to administrative error.

2. On March 13, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $43.63.

Remarks:

	/s/ Gene Boxer	03/17/2026
	** 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 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 CoStar Group (CSGP) insider Gene Boxer report in this Form 4/A?

Gene Boxer reported a tax-related share disposition. The filing shows 482 CoStar Group common shares were withheld at $43.63 per share to satisfy tax obligations, and clarifies this amount as a correction of an earlier administrative error.

How many CoStar Group (CSGP) shares were involved in Gene Boxer’s amended filing?

The amended filing reports 482 CoStar Group common shares involved. These shares were not sold on the open market but withheld to cover tax liabilities, with Boxer remaining the direct owner of 95,463 common shares after the transaction.

Was Gene Boxer’s CoStar (CSGP) Form 4/A transaction an open-market sale?

The transaction was not an open-market sale. It was a tax-withholding disposition, meaning 482 shares were delivered back to satisfy tax obligations, rather than being sold to another investor through the market.

How many CoStar Group (CSGP) shares does Gene Boxer hold after this amended transaction?

Following the reported tax-withholding transaction, Gene Boxer directly holds 95,463 CoStar Group common shares. This figure comes from the post-transaction ownership line in the amended Form 4/A, reflecting his remaining equity stake.

What correction does Gene Boxer’s CoStar (CSGP) Form 4/A disclose?

The Form 4/A specifies that the reported amount reflects a correction due to administrative error. This indicates the amendment is updating previously reported data, rather than documenting a newly executed market trade or change in trading strategy.

What price per share was used in Gene Boxer’s CoStar (CSGP) tax-withholding entry?

The filing reports a price of $43.63 per CoStar Group common share for the 482-share tax-withholding disposition. A footnote adds that this figure equals the Nasdaq closing price on March 13, 2026, the last preceding business day.