CoStar HR chief covers taxes with 2,873 shares

CoStar Group’s Chief Human Resources Officer Michael J. Desmarais reported a tax-withholding disposition of 2,873 shares of common stock at $43.63 per share.

Accepted by SEC EDGAR 03/17/2026 - 04:12 PM EDT

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Form Type

Rhea-AI Filing Summary

CoStar Group’s Chief Human Resources Officer Michael J. Desmarais reported a tax-withholding disposition of 2,873 shares of common stock at $43.63 per share. This type F transaction reflects shares withheld to cover taxes, not an open-market sale. He now directly holds 87,725 shares.

Insider Trade Summary

Exercise Price or Tax Liability: 2,873 shares

Exercise Price or Tax Liability 1 txn

Insider DESMARAIS MICHAEL J

Role Chief Human Resources Officer

Type	Security	Shares	Price	Value
Exercise Price or Tax Liability	Common Stock, par value $0.01 per share	2,873	$43.63	$125K

Holdings After Transaction: Common Stock, par value $0.01 per share — 87,725 shares (Direct)

Footnotes (1)

F1. On March 13, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $43.63.

FAQ

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What insider transaction did CoStar Group (CSGP) report for Michael J. Desmarais?

CoStar Group reported that Chief Human Resources Officer Michael J. Desmarais had 2,873 common shares disposed in a tax-withholding transaction. This was coded as an F transaction, meaning shares were used to satisfy tax obligations rather than sold on the open market.

Was the CoStar Group (CSGP) insider transaction an open-market sale?

No, the transaction was not an open-market sale. It was coded F, indicating a tax-withholding disposition where 2,873 shares were delivered to cover tax liabilities, rather than voluntarily sold by the insider through market trading.

How many CoStar Group (CSGP) shares does Michael J. Desmarais hold after the filing?

After the tax-withholding disposition, Michael J. Desmarais directly holds 87,725 shares of CoStar Group common stock. This figure comes from the post-transaction ownership reported in the Form 4 and shows his remaining equity stake following the withholding event.

What price was used for the CoStar Group (CSGP) tax-withholding shares?

The tax-withholding disposition used a price of $43.63 per share for the 2,873 CoStar Group shares. A footnote notes this was the Nasdaq closing price on March 13, 2026, the last preceding business day before the transaction date recorded in the filing.

Does the CoStar Group (CSGP) Form 4 indicate any option exercises or derivative activity?

The Form 4 does not report any derivative securities transactions. It only shows a non-derivative, tax-withholding disposition of 2,873 common shares, with no accompanying option exercises or remaining derivative positions listed in the derivative summary section of the filing.

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Form 4 Insider Transactions: What Each Field Means →

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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^*

DESMARAIS MICHAEL J

(Last)

(First)

(Middle)

C/O COSTAR GROUP, INC.

1201 WILSON BLVD.

(Street)

ARLINGTON

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)
	Chief Human Resources Officer

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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock, par value $0.01 per share	03/15/2026		F		2,873	D	$43.63⁽¹⁾	87,725	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. 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, Attorney-in-Fact	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.

Source: View Original Filing on SEC EDGAR