California’s New Single‑Firm Antitrust Law Takes Effect 2027

California’s newly enacted single‑firm antitrust law, effective 2027, marks a significant shift in U.S. regulatory enforcement. Unlike traditional antitrust statutes that target conduct between companies, this law empowers federal regulators to take action against conduct that harms competition solely by the actions of an individual firm. The provision targets organizations with market power—meaning Big Tech and large AI enterprises will face a higher scrutiny for product bundling, data practices, and other monopoly‑like behaviors that do not involve direct agreements with rivals. The legislation also clarifies the definition of ‘market power’ and imposes higher penalties for violations, addressing long‑standing concerns that existing statutes were too focused on horizontal collusion. For practice, firms must revisit compliance frameworks, reassess pricing, bundling, and data‑sharing strategies, and monitor enforcement guidance issued by the Federal Trade Commission and Department of Justice. The broader cross‑jurisdictional coverage—highlighting parallel EU and UK regulatory moves—conveys a global shift toward tighter scrutiny of tech industry conduct.