CoStar (CSGP) CFO granted 12,268 deferred stock units

Rhea-AI Filing Summary

CoStar Group’s Chief Financial Officer Christian M. Lown received an equity compensation award tied to his annual incentive. On March 10, 2026, he was granted 12,268 shares of common stock at no cash cost to him, recorded as a grant or award acquisition. According to the company’s Management Stock Purchase Plan, all or part of his annual cash incentive was converted into Deferred Stock Units at $46.34 per unit, and he was awarded an equal number of Restricted Stock Units that vest in full after four years. Following this grant, Lown directly holds 135,250 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

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^*

LOWN CHRISTIAN M.

(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 Financial 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		12,268	A	(1)	135,250	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 insider transaction did CoStar Group (CSGP) report for its CFO?

CoStar Group reported that CFO Christian M. Lown received a grant of 12,268 shares of common stock as equity compensation. The award was recorded at zero purchase price and arose from converting his annual cash incentive into stock-based units.

Was the CoStar Group (CSGP) CFO’s Form 4 transaction a stock purchase or compensation award?

The transaction was a compensation-related award, not an open-market stock purchase. It reflects a grant of 12,268 common shares under a Management Stock Purchase Plan, where cash incentive pay was converted into stock-based units and Restricted Stock Units.

How many CoStar Group (CSGP) shares does the CFO hold after this Form 4 transaction?

After the reported award, CFO Christian M. Lown directly holds 135,250 shares of CoStar Group common stock. This figure includes the 12,268 shares granted on March 10, 2026, and represents his post-transaction direct ownership position.

What is the structure of the CoStar Group (CSGP) Management Stock Purchase Plan mentioned?

Under the Management Stock Purchase Plan, all or part of the CFO’s annual cash incentive is converted into Deferred Stock Units at $46.34 per unit. The company then awards an equal number of Restricted Stock Units that vest in full after four years.

Did the CoStar Group (CSGP) CFO pay cash for the 12,268 awarded shares?

No cash was paid for the 12,268 awarded shares. The Form 4 shows a transaction price of $0.00 per share because the award came from converting his annual cash incentive into Deferred Stock Units and corresponding Restricted Stock Units, rather than an open-market purchase.