CSGP: Leadership change · Company disclosure

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On July 13, 2026, the Board of Directors (the “Board”) of CoStar Group, Inc. (the “Company” or “CoStar Group”) appointed Robin Rossmann to serve as the Company’s Chief Financial Officer, effective July 31, 2026 (“Effective Date”). Mr. Rossmann, 45, who currently serves as the Company’s Managing Director, Europe, and is a member of the Company's executive leadership team, brings more than 20 years of financial, operational and strategic leadership experience to the role of Chief Financial Officer. Over his nearly seven years with the Company, Mr. Rossmann has led several of CoStar Group’s businesses internationally, distinguished himself by dramatically improving the margins of CoStar Group's European business while delivering double-digit revenue growth and launching CoStar in France. Rossmann joined STR in 2016, leading its businesses across EMEA, Asia Pacific and Latin America, and became part of CoStar Group through the Company's acquisition of STR in 2019. Over the past decade with STR and CoStar Group, he has played a central role in launching CoStar Group products across global markets, executing and integrating acquisitions, scaling international operations and advancing strategic initiatives that have strengthened the Company's competitive position. Prior to joining STR, Rossmann spent 13 years at Deloitte, where he served as a Senior Director advising many of the world's leading public and private real estate and hospitality companies across the United States, the United Kingdom and other international markets. His experience included financial assurance, internal controls and risk management, financial and