CoStar Opposes Zillow Bid for Access to Chicago Home Listings in Escalating Real Estate Dispute

June 10, 2026 - 18:06

CoStar Group has formally opposed Zillow Group's bid to gain access to residential property listings in Chicago, marking the latest escalation in a high-stakes legal dispute between the two real estate giants. The conflict centers on control over listing data, which is considered a critical asset for companies competing in the online housing market.

In a court filing, CoStar argued that Zillow's request should be denied, claiming the move is an overreach that could undermine fair competition. CoStar, which operates the Homes.com platform, has been aggressively expanding its residential footprint and views the Chicago market as a key battleground. The company contends that Zillow is attempting to use legal tactics to gain an unfair advantage rather than competing on the merits of its own services.

Zillow, meanwhile, has pushed for access to the listings, arguing that consumers benefit from broad data availability and that restrictions limit transparency in the housing market. The dispute highlights the growing tension between traditional multiple listing services and newer digital platforms that rely on aggregated data.

Legal experts say the outcome could set a precedent for how listing data is shared across the industry. Both companies have invested heavily in their respective real estate portals, and the fight over Chicago listings is seen as a test case for similar battles in other major cities. A hearing on the matter is expected in the coming weeks.