On February 10, 2026, California Governor Gavin Newsom signed into law SB 25 requiring a party that submits a federal Hart-Scott-Rodino (HSR) filing to provide that filing to the California AG, if the party has qualifying ties to California. The new law will take effect on January 1, 2027.
Notably, the new law is emblematic of a larger trend within California and other states to take on a larger role in premerger antitrust enforcement. For more detail, see this Latham Client Alert.
California’s law, like Washington’s and Colorado’s, is based on the Uniform Antitrust Premerger Notification Act (APNA). It requires a party making a federal HSR filing to provide a copy of that filing to the California AG within one business day of submission to the federal government if:
Parties making filings under the first prong must, in addition to the HSR form itself, include the documentary materials submitted to federal agencies alongside the HSR form. Parties making filings under the second prong are only obligated to provide such documentary materials upon request by the California AG. In all cases, reproducing a filing to the California AG is a non-suspensory process; there is no waiting period. The deal may close before any California AG review concludes.
All submissions enjoy statutory protections from disclosure and must be kept confidential by the California AG.The California AG has indicated that they are building the infrastructure required to accept submitted filings in a secure manner. However, the California AG is statutorily authorized to share the submission with other state attorneys general if such states also have a substantially similar law.SB 25 identifies the APNA and “substantively equivalent acts” as qualifying laws allowing disclosure.
SB 25 permits the California AG to — and the California AG has signaled its inclination to — charge fees of $1,000 and $500 to filers making filings under the first and second prongs, respectively. Similarly, SB 25 authorizes the collection of up to $25,000 per day in fines for non-compliant filers.
California is the largest state to pass an APNA-like premerger notification statute thus far, though more are expected to follow suit. Indeed, legislatures in New York, Hawaii, Indiana, West Virginia, and the District of Columbia are considering similar laws. The enactment of these laws will likely increase the number of state-level investigations both independent of and in coordination with federal premerger investigations. In recent years, several states have signaled an increasing willingness to challenge deals in court. Colorado and Washington filed independent state court lawsuits to block the proposed Kroger-Albertsons grocer merger, and multiple states, including California, recently intervened to challenge a proposed tech merger. Previous federal court actions include California, New York, and other states filing suit to block a telecom merger in the Southern District of New York.
Relatedly, although California’s state antitrust law does not presently authorize premerger litigation, California’s Law Review Commission is actively considering amending the Cartwright Act to address anti-competitive mergers. This would be a further expansion of the Cartwright Act, following recent amendments that went into effect on January 1, 2026, to cover certain algorithmic pricing systems and lower pleading standards in antitrust litigation.