CoStar Group Inc. has petitioned the U.S. Supreme Court to review antitrust counterclaims brought by its competitor, Commercial Real Estate Exchange Inc. (CREXi). This move follows a series of legal battles between the two companies over alleged monopolistic practices in the commercial real estate information market.
The dispute began when CoStar filed a lawsuit against CREXi, accusing it of copyright infringement for allegedly using CoStar’s images and information without permission. In response, CREXi filed antitrust counterclaims, alleging that CoStar engaged in monopolistic behavior by entering into exclusive agreements with brokers and implementing technological barriers to prevent brokers from working with competitors. ([law.justia.com](https://law.justia.com/cases/federal/appellate-courts/ca9/23-55662/23-55662-2025-06-23.html?utm_source=openai))
Initially, the U.S. District Court for the Central District of California dismissed CREXi’s antitrust counterclaims, stating that CREXi failed to demonstrate CoStar’s monopoly power and that the agreements in question were not exclusive. However, the Ninth Circuit Court of Appeals reversed this decision, finding that CREXi had plausibly alleged that CoStar possessed monopoly power and engaged in anticompetitive conduct. ([caselaw.findlaw.com](https://caselaw.findlaw.com/court/us-9th-circuit/117679121.html?utm_source=openai))
CoStar subsequently sought a rehearing of the Ninth Circuit’s decision, which was denied. The appellate panel’s refusal to revisit its ruling left CoStar facing allegations of monopolizing commercial listing markets. ([usaherald.com](https://usaherald.com/9th-circuit-costar-antitrust-clash-escalates-after-rehearing-bid-rejected/?utm_source=openai))
In its petition to the Supreme Court, CoStar argues that the Ninth Circuit’s decision raises significant legal questions regarding the application of antitrust laws to exclusive dealing arrangements and technological barriers. CoStar contends that the appellate court’s ruling conflicts with established legal principles and could have broader implications for businesses operating in similar markets.
CREXi has opposed CoStar’s petition, asserting that the Ninth Circuit’s decision does not warrant Supreme Court review. CREXi argues that there is no circuit split regarding de facto exclusive dealing claims and that CoStar’s petition attempts to manufacture legal questions out of disagreements with the appellate court’s interpretation of factual allegations at the motion to dismiss stage. ([mlex.com](https://www.mlex.com/mlex/articles/2441982/crexi-opposes-us-supreme-court-review-of-antitrust-claims-against-costar?utm_source=openai))
The Supreme Court’s decision on whether to grant certiorari in this case will be closely watched by legal professionals and businesses in the commercial real estate sector, as it could clarify the boundaries of antitrust liability concerning exclusive dealing and technological restrictions in competitive markets.