The CoStar Group, Inc. 2025 Stock Incentive Plan (the “Plan”) authorizes the issuance of 13,200,000 shares of CoStar Group, Inc. (the “Company”) common stock, par value $0.01 per share (“Common Stock”). Pursuant to Rule 416(a) of the Securities Act of 1933, as amended (the “Securities Act”), this registration statement shall also cover any additional shares of Common Stock that become issuable under the Plan by reason of any stock dividend, stock split, or similar transaction. The Plan was approved by the Board of Directors of the Company and the Company’s stockholders at the Company’s 2025 Annual Meeting of Stockholders.

Estimated in accordance with Rule 457(c) and (h) under the Securities Act solely for the purpose of calculating the registration fee. The proposed maximum offering price per share is based upon the average of the high and low prices per share of Common Stock as reported on the Nasdaq Global Select Market on July 18, 2025.