CoStar Group (CSGP) CHRO gets 17,926 RSUs, disposes shares for taxes

Rhea-AI Filing Summary

CoStar Group Chief Human Resources Officer Michael J. Desmarais reported routine equity compensation activity. He received a grant of 17,926 restricted stock units, each representing one future share of CoStar Group common stock. The restricted stock units vest in three equal installments on March 1, 2027, March 1, 2028, and March 1, 2029.

To cover tax obligations, 6,353 shares of common stock were disposed of at a price of $44.63 per share through a tax-withholding transaction rather than an open-market sale. Following these transactions, Desmarais directly held 72,922 shares of CoStar Group common stock.

Insider Trade Summary

2 transactions reported

Mixed 2 txns

Insider DESMARAIS MICHAEL J

Role Chief Human Resources Officer

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock, par value $0.01 per share	6,353	$44.63	$284K
Grant/Award	Restricted Stock Units	17,926	$0.00	--

Holdings After Transaction: Common Stock, par value $0.01 per share — 72,922 shares (Direct); Restricted Stock Units — 17,926 shares (Direct)

Footnotes (1)

1. On February 27, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.63. Includes 157 shares acquired under the CoStar Group, Inc. Employee Stock Purchase Plan. Each restricted stock unit represents a contingent right to receive one share of CoStar Group, Inc. common stock. The restricted stock units vest in three equal installments on March 1, 2027, March 1, 2028 and March 1, 2029.

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^*

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)
02/27/2026

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	03/01/2026		F		6,353	D	$44.63(1)	72,922(2)	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
Restricted Stock Units	(3)	02/27/2026		A		17,926		(4)	(4)	Common Stock, par value $0.01 per share	17,926	$0	17,926	D

Explanation of Responses:

1. On February 27, 2026, the last preceding business day, the closing price of the Company's common stock on Nasdaq was $44.63.

2. Includes 157 shares acquired under the CoStar Group, Inc. Employee Stock Purchase Plan.

3. Each restricted stock unit represents a contingent right to receive one share of CoStar Group, Inc. common stock.

4. The restricted stock units vest in three equal installments on March 1, 2027, March 1, 2028 and March 1, 2029.

Remarks:

Exhibit 24 - Power of Attorney

	/s/ Gene Boxer, Attorney-in-Fact	03/03/2026
	** 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 insider transactions did CoStar Group (CSGP) report for Michael J. Desmarais?

CoStar Group’s Chief Human Resources Officer Michael J. Desmarais reported a grant of 17,926 restricted stock units and a tax-withholding disposition of 6,353 common shares at $44.63 per share, leaving him with 72,922 directly held CoStar common shares.

Were the recent CoStar Group (CSGP) insider transactions open-market stock sales?

The filing shows no open-market sales. Instead, 6,353 CoStar common shares were disposed of as a tax-withholding transaction at $44.63 per share, linked to equity compensation, rather than a discretionary sale into the market by Michael J. Desmarais.

How many restricted stock units did CoStar’s CHRO receive in the latest grant?

Michael J. Desmarais received 17,926 restricted stock units. Each unit represents a contingent right to one share of CoStar Group common stock, providing long-term incentive compensation that aligns his interests with shareholders as the units vest over several future years.

When will Michael J. Desmarais’s new CoStar (CSGP) restricted stock units vest?

The 17,926 restricted stock units vest in three equal installments. The vesting dates are March 1, 2027, March 1, 2028, and March 1, 2029, creating a multi-year incentive schedule tied to his continued service at CoStar Group.

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

After the reported transactions, Michael J. Desmarais directly holds 72,922 shares of CoStar Group common stock. This total includes shares already owned plus equity-related activity, reflecting his ongoing ownership stake in the company’s common equity.

What price was used for the CoStar (CSGP) tax-withholding share disposition?

The tax-withholding disposition of 6,353 CoStar common shares used a price of $44.63 per share. A related note states that CoStar’s common stock closed at $44.63 on Nasdaq on February 27, 2026, the last preceding business day before the vesting-related activity.