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

By  |  June 10, 2026
CoStar Opposes Zillow Bid for Access to Chicago Home Listings in Escalating Real Estate Dispute

CoStar Group has entered a growing legal battle over access to residential real estate listings, urging a court to reject Zillow Group Inc.’s effort to secure continued access to key home listing data in the Chicago market.

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    According to Bloomberg, CoStar filed an amicus brief on Wednesday opposing Zillow’s request for a preliminary injunction that would require a Chicago-area real estate data provider to continue supplying the company with home listings feeds while litigation is ongoing.

    The dispute is part of a broader fight over how residential property listings are distributed and displayed across online real estate platforms in the United States. Zillow is seeking court intervention after losing access to certain listing data, while CoStar argues that granting the injunction would effectively endorse conduct it characterizes as anticompetitive.

    WHAT’S NEXT IN ANTITRUST™

    Per Bloomberg, CoStar told the court that Zillow should not be permitted to retain the ability to restrict the display of certain “pre-market” private listings that are not broadly available to consumers. The company argued that forcing the Chicago-area data provider to continue delivering listings to Zillow would reward behavior that CoStar contends harms competition in the housing market.

    Related: Supreme Court Lets CREXi Antitrust Case Against CoStar Move Forward

    The legal clash comes amid heightened tensions within the real estate industry over listing transparency and access to property data. Zillow has recently been involved in litigation with industry participants over listing policies and the handling of properties marketed before being broadly published online. Reports indicate that Zillow sued Midwest Real Estate Data (MRED) and Compass, alleging efforts to pressure the company over how it displays certain listings.

    According to Bloomberg, CoStar’s filing marks the latest escalation in a dispute that could have significant implications for control of residential real estate information and the competitive dynamics among major online housing platforms. The outcome of the case may influence how listing data is shared across the industry and whether companies can impose restrictions on the visibility of homes before they are publicly marketed.

    Source: Bloomberg