A class action complaint filed in April 2026 in the Eastern District of Virginia is putting CoStar’s dominance under scrutiny. The plaintiff, Shapiro Hospitalities, a boutique commercial real estate brokerage firm based in Brooklyn, is bringing the case on behalf of itself and all similarly situated CoStar customers under Sections 1 and 2 of the Sherman Act.

The complaint alleges that CoStar maintained its monopoly through two principal mechanisms. The first involves a set of long-term enterprise agreements with CBRE, JLL, and Cushman and Wakefield, the three largest national CRE brokerage firms, that the complaint alleges included mutual non-compete provisions preventing those firms from launching competing listing or data services. According to the complaint, the three brokerages had actually begun planning a data-sharing consortium to create a cheaper CoStar alternative before abandoning the effort out of fear of retaliation. A former JLL executive is quoted in the complaint saying that “people were nervous that CoStar was going to find out and stop our service.”

The second mechanism involves what the complaint calls the Customer Terms, a set of uniform contractual provisions that govern every CoStar and LoopNet subscriber. The complaint describes a structure in which customers are told they are granting CoStar a “non-exclusive license” to their submitted content, while other provisions in the same agreement effectively transfer ownership of that content to CoStar once it is integrated into the platform. Once a listing photograph or data point is uploaded, it becomes part of what the terms define as the Product, which CoStar claims exclusive ownership over. Customers are then contractually prohibited from sharing any portion of the Product, including content they originally created and paid for, with any competing platform.

A CoStar employee is quoted in the complaint having told a customer directly that “when photos are uploaded to CoStar the ownership rights are given up in our Terms and Conditions,” and a separate employee admitted under oath that supervisors instructed staff that once brokers provided information or photos to CoStar, those assets “became CoStar’s property.”

The complaint alleges CoStar enforces these terms in several ways: watermarking broker-submitted photographs, blocking competitor IP addresses, scraping competitor platforms for cross-listed content, and sending threatening letters to customers who shared their own photographs with Crexi or other platforms. The complaint includes extensive quotes from brokers who discovered their own photographs watermarked with CoStar’s logo and complained that they had paid for the images themselves, received no explanation from CoStar, and were effectively prevented from sharing their own marketing materials with other platforms.

The case has a specific legal history that gives it momentum. Crexi, which CoStar sued for copyright infringement in 2020, brought antitrust counterclaims raising nearly identical allegations to those in this complaint. Those counterclaims were found plausible twice by the Ninth Circuit Court of Appeals, most recently in a 2025 ruling, and the Supreme Court declined to hear CoStar’s appeal in March 2026. The Crexi antitrust claims are now heading toward discovery and trial, and the class action in Virginia is proceeding alongside them.

There are some parallels to the RealPage litigation, which resulted in nearly $360 million in settlements from landlords and a DOJ consent agreement limiting how the company can use competitive data. Both cases involve a technology platform that aggregated data from competing customers in ways alleged to harm market competition. The key difference is that RealPage’s alleged harm ran to renters through pricing coordination, while CoStar’s alleged harm runs to its own customers through monopolistic pricing and the suppression of competing platforms. The RealPage experience also demonstrated that the operators who used the platform faced liability alongside the company that built it, a dynamic that CoStar’s customers, who are named as potential class members, will be watching closely as this case develops.

For CoStar, the litigation creates a set of challenges that extend beyond any single legal outcome. The company is simultaneously defending the Crexi antitrust claims heading toward trial, facing this new class action from its own customers. For the broader CRE technology market, the case puts into formal legal dispute questions about data ownership, platform access, and competitive fairness that the industry has been debating informally for years. Whether customers can freely share their own listing information with competing platforms, and whether CoStar’s contractual terms prevent them from doing so, is not an abstract legal question. It is the foundational question that determines whether meaningful competition in CRE data services is possible at all.

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