CoStar CEO buys 83,300 shares in open market

CoStar Group, Inc. founder and CEO Andrew C. Florance reported purchasing 83,300 shares of common stock on August 4, 2026 at an average price of $29.89 per share, based on prices ranging from $29.57 to $29.99.

Accepted by SEC EDGAR 08/05/2026 - 09:27 AM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

CoStar Group, Inc. founder and CEO Andrew C. Florance reported purchasing 83,300 shares of common stock on August 4, 2026 at an average price of $29.89 per share, based on prices ranging from $29.57 to $29.99. After this open-market purchase, he directly holds 1,806,165.03 shares.

Insider Trade Summary

Net Buyer: 83,300 shares

Net Buy 1 txn

Insider FLORANCE ANDREW C

Role Founder and CEO

Bought 83,300 shs ($2.49M)

Type	Security	Shares	Price	Value
Purchase	Common Stock, par value $0.01 per share F1	83,300	$29.89	$2.49M

Holdings After Transaction: Common Stock, par value $0.01 per share — 1,806,165.03 shares (Direct)

Footnotes (1)

1. F1. Average based on sales prices ranging from $29.57 to $29.99.

Key Figures

Shares purchased: 83,300 shares Average purchase price: $29.89 per share Trade price range: $29.57–$29.99 per share +1 more

4 metrics

Shares purchased 83,300 shares Common stock acquired by Andrew C. Florance on August 4, 2026

Average purchase price $29.89 per share Average price for the 83,300 shares bought, subject to price range footnote

Trade price range $29.57–$29.99 per share Footnote states average is based on prices ranging from $29.57 to $29.99

Direct holdings after transaction 1,806,165.03 shares Total CoStar Group common shares directly owned by Andrew C. Florance after the purchase

Key Terms

par value, open market, private transaction

3 terms

par value financial

"Common Stock, par value $0.01 per share"

Par value is the fixed amount printed on a bond or stock that represents its original value when issued. It’s like the face value of a coin or bill—what the issuer promises to pay back or the starting price of a stock—though it often doesn’t change with market prices. It matters because it helps determine certain financial details, like how much the company will pay back at maturity.

open market financial

"Purchase in open market or private transaction"

An open market is a system where buying and selling of goods, services, or financial assets happen freely without restrictions or special controls. For investors, it means they can trade assets easily and quickly, which helps determine fair prices based on supply and demand. This environment encourages transparency and competition, making it easier to buy or sell with confidence.

private transaction financial

"Purchase in open market or private transaction"

A private transaction is the sale or transfer of securities, assets, or ownership stakes carried out directly between a small number of parties rather than on a public exchange. For investors it matters because these deals are less visible and often less liquid than public trades, so pricing can be harder to verify, the investment can be harder to sell quickly, and buyers or sellers may gain strategic advantages not available in open markets — like negotiated terms similar to a private garage sale versus a crowded marketplace.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did CoStar Group (CSGP) report for Andrew Florance?

CoStar Group reported that Andrew C. Florance, its founder and CEO, purchased 83,300 shares of common stock on August 4, 2026. The transaction was reported as a direct open-market purchase of CoStar Group common stock.

At what price did Andrew Florance buy CoStar Group (CSGP) shares?

Andrew Florance bought the shares at an average price of $29.89 per share. A footnote explains this figure is based on trade prices ranging from $29.57 to $29.99, indicating multiple executions aggregated into a single reported average price.

How many CoStar Group (CSGP) shares does Andrew Florance own after this trade?

Following the reported purchase, Andrew Florance directly owns 1,806,165.03 shares of CoStar Group common stock. This post-transaction holding reflects his direct ownership position as disclosed in the Form 4 after acquiring the additional 83,300 shares.

Was the latest CoStar Group (CSGP) insider trade under a Rule 10b5-1 plan?

The filing indicates the trade was not made under a Rule 10b5-1 trading plan. The document-level checkbox for Rule 10b5-1 plans is marked false, meaning this purchase was not executed pursuant to a pre-arranged trading plan framework.

What type of transaction was reported in this CoStar Group (CSGP) Form 4?

The Form 4 reports a purchase of common stock, coded as a “P” transaction, described as a “Purchase in open market or private transaction.” It covers non-derivative CoStar Group common shares acquired directly by Andrew Florance.

How many CoStar Group (CSGP) shares did Andrew Florance buy in total?

Andrew Florance acquired a total of 83,300 shares of CoStar Group common stock in this reported transaction. The filing’s transaction summary also identifies this as a net buy of 83,300 shares, with no offsetting sales or derivative exercises.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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^*

FLORANCE ANDREW C

(Last) (First) (Middle)

C/O COSTAR GROUP, INC.

1201 WILSON BLVD.

(Street)

ARLINGTON VIRGINIA 22209

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
COSTAR GROUP, INC. [ CSGP ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Founder and CEO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/04/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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

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	08/04/2026		P		83,300	A	$29.89(1)	1,806,165.03	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. Average based on sales prices ranging from $29.57 to $29.99.

Remarks:

	/s/ Gene Boxer, Attorney-in-Fact	08/05/2026
	** 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.
* Form 4: SEC 1474 (03-26)