Consumers sue Anthropic, OpenAI, SpaceXAI, and Google alleging antitrust pact to slow AI development

Key points

• Buist v. Anthropic, No. 3:26-cv-10693, alleges horizontal coordination under Sherman Act Section 1 to restrict output and product quality across frontier AI models.U.S. District Court, N.D. Cal. (ECF No. 1, LexRegister copy)Bloomberg Law
• Plaintiffs define the relevant market as paid consumer subscriptions to general-purpose frontier AI assistants, covering ChatGPT, Claude, Grok, and Gemini.U.S. District Court, N.D. Cal. (ECF No. 1, LexRegister copy)
• The complaint cites public executive statements and multi-company working group meetings since July 2026 as evidence of an actionable conspiracy.U.S. District Court, N.D. Cal. (ECF No. 1, LexRegister copy)PoliticoThe Hill
• Plaintiffs argue each company can set its own safety thresholds and guardrails without agreeing with rivals, and that no statute exempts the alleged pact.U.S. District Court, N.D. Cal. (ECF No. 1, LexRegister copy)PoliticoThe Hill
• The proposed class action seeks treble damages under Clayton Act Section 4 and injunctive relief under Section 16 barring horizontal agreements.U.S. District Court, N.D. Cal. (ECF No. 1, LexRegister copy)Bloomberg Law

Sources5 articles across 5 outlets

• Bloomberg Law

  • OpenAI, Anthropic, Google, SpaceXAI Hit With Antitrust LawsuitSept. 18, 2026

• Dario Amodei (personal site)

  • We Must Pace the FrontierSept. 12, 2026

• Politico

  • Anthropic, OpenAI, SpaceXAI, Google sued over call to ‘pace’ AI developmentSept. 19, 2026

• The Hill

  • Lawsuit accuses Anthropic, OpenAI, SpaceXAI, Google of AI pacing ‘collusion’Sept. 19, 2026

• U.S. District Court, N.D. Cal. (ECF No. 1, LexRegister copy)

  • Complaint, Buist v. Anthropic, PBC, No. 3:26-cv-10693 (N.D. Cal. filed Sept. 18, 2026)Sept. 18, 2026

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