California joins Colorado and Washington in enacting a state-level premerger notification law, effective January 1, 2027.
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.
What SB 25 Means for Filing Parties
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:
- The filing party has its principal place of business in California; or
- The filing party, or a person it directly or indirectly controls, had annual net sales in California of at least 20% of the then operative size-of-transaction threshold of the “goods or services involved in the transaction.”1
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.
