California's COMPETE Act Adds Single-Firm Monopolization to the Cartwright Act

California has closed one of the most visible gaps in its antitrust toolkit. On September 30, 2026, Governor Gavin Newsom signed the COMPETE Act, amending the Cartwright Act so that, for the first time, the state statute reaches single-firm conduct: it makes it unlawful to monopolize or monopsonize. The full text was not available to this briefing, so scope, any thresholds or market definitions, exemptions, enforcement authority and remedies remain unverified and should be read directly before reliance.

Why sophisticated counsel should care: California is a large, economically concentrated market with heavy platform, technology, retail, healthcare and labor-market overlap with major-firm clients. A state-law prohibition on monopolization supplies a direct legal duty and, importantly, an in-state forum, expanding parallel-risk and follow-on exposure alongside federal Sherman Act and FTC Act theories. Monopsony language also reaches buyer-side power, relevant to employers, staffing firms, aggregators and other large purchasers.

Practical next steps: read the enacted text and any Attorney General guidance, then screen the client portfolio for California share or buyer concentration; map exclusive arrangements, restraints and no-poach-type conduct; assess how California-only risk interacts with Hart-Scott-Rodino filings, which do not displace state law; and watch for constitutional or preemption challenges.