Antitrust Law Daily Wrap Up, ANTITRUST NEWS: CoStar Group petitions for certiorari in commercial real estate listings antitrust litigation, (Dec 15, 2025)

By Kenneth H. Ryesky, M.B.A., J.D.

Circuit split on exclusive dealing and refusal to deal issues "is especially pronounced when defendants take steps to limit or block competitors' access to new technologies."

A commercial real estate listing service has petitioned the Supreme Court for certiorari following the Ninth Circuit's reinstatement of antitrust counterclaims against it by the federal district court. The petition urges the Supreme Court to clarify policy on the issues of refusal to deal and exclusive dealing contracts, so that such issues in antitrust cases can be disposed of during the interlocutory dismissal motion stage of litigation; this, the petition exhorts, would facilitate judicial economy by avoiding unnecessary discovery, and ultimately promote innovation in the market (Costar Group, Inc. v. Commercial Real Estate Exchange, Inc., No. 25-667 (U.S. Dec. 15, 2025)).

Background. The CoStar Group, Inc. (CoStar) has developed what it rightly touts as "the most comprehensive database of commercial real estate in the world." Real estate brokers can access this database on a subscription and/or fee basis. This database entails, among other things, two platforms: (1) "LoopNet," through which brokers advertise properties for sale or lease; and (2) "LoopLink," to which brokers can upload their LoopNet listings and other information, including photographs, and then directly link their own LoopNet listings for display on the brokers' own Internet websites.

Commercial Real Estate Exchange, Inc. (CREXi) competes with CoStar in the commercial real estate listing, information, and auction markets. CoStar' terms of use include provisions by which (1) brokers hold the intellectual property rights to the images and data they upload to the LoopNet and/or LoopLink platforms; (2) CoStar has a non-exclusive license to carry the brokers' intellectual property in its platforms; and (3) brokers may only download material from CoStar's platforms (which can include CoStar's own data) for use on their own websites. These terms of use, according to CoStar, mean that brokers can "do almost anything they want with their own content," but "cannot take information directly from CoStar’s platforms and provide it to CoStar’s competitors.

CoStar sued CREXi in federal district court, alleging infringement of intellectual property. CREXi counterclaimed antitrust violations under the Sherman Act and the California state statutes. The district court dismissed CREXi's antitrust counterclaims. The Ninth Circuit reversed that dismissal. CoStar has petitioned the Supreme Court for certiorari.

Exclusive dealing. CoStar's certiorari petition raises the question of "whether a 'de facto' exclusive dealing claim is cognizable under the Sherman Act in the absence of expressly stated exclusive contractual terms, programs, or policies." Per the de facto exclusive dealing theory, courts need to go beyond the contractual verbiage to evaluate the practical effects of a policy. There is now a split among the circuits: (1) the Second and Eighth

Circuits have rejected that theory under the arrangements used by CoStar; (2) the Third, Tenth, and Eleventh Circuits have recognized the theory as a cognizable antitrust claim, but with limitations; and (3) the instant Ninth Circuit decision appealed from recognizes the claim "with no guardrails." This, says CoStar's petition, causes confusion.

The certiorari petition further asserts that de facto exclusive dealing claim as found cognizable by the Ninth Circuit in this case is an incorrect application of the Sherman Act. The antitrust counterclaim by CREXi was that CoStar's terms of service were misunderstood by some of the brokers. Even under the rulings of the Third, Tenth, and Eleventh Circuits, this misunderstanding by the brokers was not anticompetive conduct on CoStar's part. Indeed, CoStar's terms of service expressly state that CoStar's license to use the brokers' data is non-exclusive.

Refusal to deal. CoStar's certiorari petition raises the question of "Whether a refusal-to-deal claim prohibited by Verizon Communications Inc. v. Law Offices of Curtis V. Trinko, LLP, 540 U.S. 398 (2004), is cognizable if the plaintiff calls it something else." The Trinko case enunciated the rule that except in certain rare circumstances, parties may choose to deal with whomever they please. Although this rule has been reasserted in subsequent Supreme Court decisions, the rule's application by the circuits has been inconsistent; courts in some circuits uphold the refusal to deal rule, while in other circuits the courts will decline to apply the Trinko rule when the plaintiff characterizes its claim "as something other than a 'refusal to deal' allegation." This, the certiorari petition asserts, gives antitrust plaintiffs a workaround to evade the Trinko rule.

For reasons similar to those stated in its exclusive dealing discourse, the certiorari petition insists that the Ninth Circuit's sustainment of CREXi's antitrust claims was incorrect, identifying other instances where the Supreme Court has granted certiorari for similar errors by the Ninth Circuit. The petition states that "The Ninth Circuit's failure to apply Trinko conflicts with decisions of the Tenth and D.C. Circuits, is inconsistent with this Court’s precedents, and will discourage innovation and undermine antitrust policy."

The Case is No. 25-667.

Attorneys: Melissa Arbus Sherry (Latham & Watkins LLP) for CoStar Group, Inc.

Companies: CoStar Group, Inc.; Commercial Real Estate Exchange, Inc.

News: Antitrust