CoStar Group (CSGP) CHRO receives 17,676-share equity award

Rhea-AI Filing Summary

CoStar Group’s Chief Human Resources Officer, Michael J. Desmarais, received a grant of 17,676 shares of common stock as reported on a Form 4. These shares were acquired at a reported price of $0.00 per share, reflecting a compensation-related award rather than a market purchase.

According to the footnote, a portion of his annual cash incentive was converted into Deferred Stock Units at $46.34 per unit, and he was also awarded an equal number of Restricted Stock Units that vest in full after four years. Following this award, Desmarais directly owns 90,598 shares of CoStar Group common stock.

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

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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^*

DESMARAIS MICHAEL J

(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)
	Chief Human Resources Officer

3. Date of Earliest Transaction (Month/Day/Year)
03/10/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock, par value $0.01 per share	03/10/2026		A		17,676	A	(1)	90,598	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. Pursuant to the Management Stock Purchase Plan, all or a portion of the reporting person's annual cash incentive amount was converted to Deferred Stock Units (each equivalent to one share of common stock) at $46.34 per unit, and the Company awarded the reporting person Restricted Stock Units that vest in full after four years for an equal number of shares of common stock.

Remarks:

	/s/ Gene Boxer, Attorney-in-Fact	03/11/2026
	** 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) report in Michael Desmarais’s latest Form 4?

CoStar Group reported that Chief Human Resources Officer Michael J. Desmarais received 17,676 shares of common stock as a compensation-related grant, bringing his direct holdings to 90,598 shares after the transaction.

How many CoStar Group (CSGP) shares did Michael Desmarais acquire in this filing?

Michael Desmarais acquired 17,676 shares of CoStar Group common stock in this Form 4. These shares were reported at a price of $0.00 per share, reflecting an equity award instead of an open-market purchase.

What is Michael Desmarais’s total CoStar Group (CSGP) shareholding after the Form 4 transaction?

After the reported transaction, Michael Desmarais directly owns 90,598 CoStar Group shares. This total includes the newly granted 17,676 shares, which increased his direct ownership position as disclosed in the Form 4.

How were the 17,676 CoStar Group (CSGP) units for Michael Desmarais determined?

Under the Management Stock Purchase Plan, all or part of Desmarais’s annual cash incentive was converted into Deferred Stock Units at $46.34 per unit, with an equal number of Restricted Stock Units awarded, each equivalent to one share of common stock.

When do Michael Desmarais’s new CoStar Group (CSGP) Restricted Stock Units vest?

The Restricted Stock Units awarded to Michael Desmarais in this transaction vest in full after four years. Once vested, each unit corresponds to one share of CoStar Group common stock, as described in the footnote.

Was Michael Desmarais’s CoStar Group (CSGP) Form 4 transaction an open-market purchase?

No, the transaction was not an open-market purchase. It was a grant of 17,676 shares at a reported price of $0.00 per share, tied to converting cash incentive compensation into equity under the Management Stock Purchase Plan.