CoStar Group (CSGP) traded lower as the market focused on renewed skepticism around the cost and timeline to monetize Homes.com, keeping pressure on the stock even after the company posted a Q1 beat on adjusted earnings and lifted its full-year adjusted EBITDA outlook. Recent target cuts and cautious positioning following earnings have kept sentiment fragile as investors look for clearer evidence that Homes.com spend is moderating and translating into durable profitability.

In its Q1 2026 update (released April 28, 2026), CoStar reported revenue of $897 million (+23% year over year) and adjusted EPS of $0.23, with adjusted EBITDA of $132 million. CoStar reaffirmed 2026 revenue guidance of $3.78–$3.82 billion and raised full-year 2026 adjusted EBITDA guidance to $780–$820 million, while guiding Q2 revenue to $922–$932 million and Q2 adjusted EBITDA to $160–$180 million. Despite the improved EBITDA outlook, investors have remained sensitive to the near-term margin drag from ongoing Homes.com investment and the pace of visible monetization.

Two additional factors have been in focus: (1) headline risk from a new antitrust class action filed in April 2026 that alleges monopolization in commercial real estate listings and information services, and (2) insider signaling. CoStar disclosed CEO Andy Florance purchased 71,430 shares on May 1, 2026 for roughly $2.5 million, a supportive datapoint but not enough to offset concerns tied to Homes.com spending and valuation resets.