On February 10, California became the latest state to enact a "mini-HSR" law when Governor Newsom signed Senate Bill No. 25 (SB 25)—the California Uniform Antitrust Premerger Notification Act—into law. This legislation, which will go into effect on January 1, 2027, requires certain parties filing premerger notifications under the federal Hart-Scott-Rodino (HSR) Act to additionally file copies of their federal filings with the California Attorney General. With California joining Washington and Colorado in adopting state-level premerger notification requirements, dealmakers should take note of these evolving compliance obligations as they plan transactions in 2027 and beyond.
HSR Act and State Analogues
Under the federal HSR Antitrust Improvements Act of 1976, parties to transactions that exceed a minimum size threshold—set at $133.9 million for 2026—must file a premerger notification with the Federal Trade Commission (FTC) and Department of Justice (DOJ) and observe a mandatory waiting period prior to closing. The purpose of the HSR regime is to allow federal agencies to assess the potential competitive impact of a transaction before consummation.
In 2025, we saw a push for widespread adoption of HSR laws at the state level following the Uniform Law Commission's publication of the model Uniform Antitrust Premerger Notification Act, which aims to promote consistency across states in merger notification requirements. Following Washington's enactment of the Act in April 2025 and Colorado's in July 2025, California is now the third state to pass legislation based on the model law. The District of Columbia, Hawaii, Indiana, and West Virginia have introduced similar bills that are still pending.
Key Provisions of SB 25
California's new law requires parties filing a federal HSR premerger notification to submit a complete electronic copy of the HSR form to the California Attorney General within one business day of filing with the federal government if either of the following criteria is met:
- Principal Place of Business. The filing person has its principal place of business in California.
- Net Sales Nexus. The filing person, or a person it directly or indirectly controls, had annual net sales in California of the goods or services involved in the transaction of at least 20% of the HSR size of transaction threshold.
For parties required to file because their principal place of business is in California, the filing must include a complete electronic copy of the additional documentary material submitted with the federal HSR form. For parties filing based solely on the California net sales nexus, the Attorney General may request additional documentary material, which must then be provided within seven business days of receipt of the request.
Filing Fees
Unlike the model law, California's statute authorizes the Attorney General to impose filing fees: $1,000 for principal place of business filings and $500 for California net sales nexus filings.
Penalties for Non-Compliance
After written notice and a three-business-day cure period, the Attorney General may impose civil penalties of up to $25,000 per day of noncompliance on parties that fail to meet the filing requirements.
Confidentiality Protections
The Attorney General is prohibited from publicly disclosing the filed materials, including the HSR form, additional documentary material, or even the existence of a filing. The materials are exempt from disclosure under the California Public Records Act. However, the Attorney General may share information with federal antitrust agencies and with attorneys general of other states that have enacted the Uniform Antitrust Premerger Notification Act or a substantively equivalent law with comparable confidentiality protections.
Effective Date
The law applies to premerger notifications filed on or after January 1, 2027.
Implications for Dealmakers
Transaction planning should now incorporate early diligence to identify applicable state-level filing obligations. Although California's law does not impose a separate waiting period—allowing transactions to proceed during the Attorney General's review if federal HSR clearance is obtained—the requirement itself, along with the potential for significant daily penalties for noncompliance, makes early identification of filing obligations essential.
As more states enact similar laws, parties to HSR-reportable deals will increasingly need to evaluate whether parallel state filings are required and coordinate with antitrust counsel to monitor evolving state requirements and adjust transaction timelines and compliance strategies accordingly.
These laws are part of a larger, ongoing trend toward increasing state oversight and regulation of healthcare transactions and investments in the healthcare industry. Bass, Berry & Sims is actively tracking these legislative trends via our interactive healthcare transactions map, available here. For more information about the Uniform Antitrust Premerger Notification Act and its implications, please contact the authors or the Bass, Berry & Sims Antitrust Team.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
