The judicial and regulatory demarcation between illegal algorithmic collusion and permissible independent utility maximization shifted decisively in late 2025. Courts now demand rigorous statistical proof that a central data aggregator—the "hub"—facilitated a meeting of minds among competitors—the "spokes"—creating a functional "rim" of concerted action. Without this rim, simultaneous use of identical revenue management software (RMS) by rivals remains insufficient to establish liability under Section 1 of the Sherman Act. The Ninth Circuit’s August 2025 ruling in Gibson v. Cendyn Group and the Department of Justice’s (DOJ) November 2025 settlement with RealPage illustrate this diverging legal standard.

Antitrust jurisprudence fundamentally distinguishes between explicit agreements and conscious parallelism. In the algorithmic era, this distinction hinges on whether the software engine acts as a conduit for exchanging nonpublic, competitively sensitive data or merely processes public market signals. The "hub-and-spoke" theory posits that a central vendor (RealPage, Yardi, Cendyn) organizes a conspiracy among vertical clients (landlords, hotels). For liability to attach, plaintiffs must prove the rim: a horizontal agreement among the spokes to adhere to the hub’s pricing logic.