California has enacted a sweeping new premerger notification requirement that will broaden the state’s role in reviewing major business transactions.
On February 10, 2026, Governor Gavin Newsom signed the California Uniform Antitrust Premerger Notification Act into law, making California the third state to implement a comprehensive state-level premerger notification regime, according to a statement released following the bill’s approval. The law is set to apply to premerger notifications filed on or after January 1, 2027.
The new statute requires certain companies involved in transactions that trigger federal Hart-Scott-Rodino, or HSR, reporting obligations to provide copies of their HSR forms to the California Attorney General. Per a statement accompanying the measure, the law is modeled on draft legislation from the Uniform Law Commission and mirrors similar frameworks previously adopted in Washington state and Colorado. However, California’s version includes notable differences, particularly with respect to filing fees and financial penalties.
Under the California Act, companies must submit their HSR filings to the state if their principal place of business is located in California or if they, or entities they control, generate annual net sales in California of at least 20 percent of the applicable HSR filing threshold for the goods or services involved in the transaction. Based on the 2026 HSR threshold of $133.9 million, that 20 percent benchmark equates to roughly $26.8 million. Given that California accounts for approximately 15 percent of total U.S. gross domestic product, the law is expected to capture a larger volume of transactions than comparable statutes in Washington and Colorado, according to a statement describing the measure’s scope.
The new requirements build upon more targeted premerger notification rules already in place in California for the health care sector and for retail grocery and pharmacy transactions.
For transactions that fall within the law’s coverage, parties must provide a copy of their HSR form to the California Attorney General within one business day of submitting the filing to federal regulators. Companies qualifying based on having their principal place of business in California must also submit the same supporting documents included in their federal HSR filing. In cases where the filing obligation is triggered by California sales volume rather than headquarters location, the Attorney General may request those supporting materials, and companies must supply them within seven business days of receiving such a request, per a statement outlining the procedural requirements.
The statute authorizes the California Attorney General to assess filing fees of $1,000 for companies filing on the basis of a California principal place of business and $500 for those filing based on in-state sales. These amounts may be adjusted for inflation no more than once every five years. By contrast, Washington and Colorado do not impose filing fees under their respective premerger notification laws.
The California Act also establishes more substantial financial penalties for noncompliance. The Attorney General may seek civil penalties of up to $25,000 per day for failure to meet the filing requirements, after providing written notice and a three-business-day opportunity to cure the violation. This maximum daily penalty exceeds the $10,000 cap in Washington and Colorado, though California’s statute expressly provides a cure period, unlike the laws in those states.
Confidentiality and information-sharing provisions in the California Act closely track those adopted in Washington and Colorado. However, California’s law includes additional safeguards. Materials submitted in connection with a notified transaction must be destroyed or returned within 120 days after the transaction closes or after the conclusion of any legal proceedings directly related to the deal, whichever occurs later. Additionally, the California Attorney General must provide five business days’ notice before disclosing submitted materials to another state’s attorney general that has a similar premerger notification requirement, according to a statement summarizing the law’s confidentiality provisions.
Source: Cleary Gottlieb