California has enacted new antitrust premerger notification requirements that will take effect on January 1, 2027. The legislation, signed by Governor Gavin Newsom on February 10, 2026, is called the California Uniform Antitrust Premerger Notification Act. It requires companies and individuals with certain connections to California to submit a copy of their Hart-Scott-Rodino (HSR) Act filings to the California Attorney General.
The law is modeled after the Uniform Antitrust Premerger Notification Act developed by the Uniform Law Commission and reflects a broader trend in which states are increasing their scrutiny of mergers and acquisitions. Similar laws went into effect in Colorado and Washington in 2026, while other states such as Nevada, Indiana, West Virginia, Hawaii, and Utah are considering similar measures.
Under the new statute, companies or individuals who file under the HSR Act must comply if they either have their principal place of business in California or have annual net sales in California related to the transaction amounting to at least 20% of the applicable HSR filing threshold. For transactions at the start of 2027, this means parties with more than approximately $26.8 million in relevant annual net sales in California will be affected.
The law mandates that eligible filers submit an electronic copy of their HSR form within one business day of filing with federal agencies. Those based in California must also provide all additional documentary material required for HSR filings; those meeting only the sales-based threshold are required to provide such materials only upon request from the Attorney General.
Filing fees are set at $1,000 for businesses headquartered in California and $500 for those meeting only the sales-based criterion.
To address confidentiality concerns, submissions made under this law are exempt from disclosure under the California Public Records Act. However, information may still be disclosed under protective order during administrative or judicial proceedings—a provision similar to federal HSR confidentiality rules.
Failure to comply with these requirements can result in civil penalties of up to $25,000 per day following written notice and a three-day period to correct any violation.
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