California Becomes Third State to Adopt "Baby HSR" Act
A growing wave of state-level merger notification requirements is reshaping the antitrust landscape for dealmakers. On February 10, 2026, Governor Gavin Newsom signed Senate Bill 25, the California Uniform Antitrust Premerger Notification Act (the Act) into law, making California the third state to require that certain parties filing Hart-Scott-Rodino (HSR) premerger notifications with federal agencies also submit those filings to the state attorney general. The Act takes effect on January 1, 2027.
The Act follows similar legislation enacted in Washington State (April 2025) and Colorado (June 2025). All three states adopted versions of the Uniform Law Commission's (ULC) 2024 model act, which was designed to give state attorneys general (AGs) access to federal HSR filings—information they otherwise cannot obtain without the parties' consent.
Filing Triggers
The Act requires a person filing a premerger notification with the federal government under the federal HSR Act to file a complete electronic copy of the HSR form with the California Attorney General within one business day of filing with the federal government if one of the following applies:
- The person has its principal place of business in California.
- The person or a person it controls directly or indirectly had annual net sales in California of the goods or services involved in the transaction of at least 20 percent of the HSR filing threshold.
The Act does not define "principal place of business," but based on the ULC model act commentary, this term is best read as referring to the place where a corporation's officers direct, control, and coordinate the corporation's activities.
As of February 17, 2026, the HSR minimum size of transaction threshold is $133.9 million. That means the current minimum threshold for the Act is $26.78 million.
Additional Documentary Material
Those required to file based on their principal place of business must include an electronic copy of all additional documentary material with their filing. Those required to file based on net sales are not initially required to provide such materials but must do so within seven business days if requested by the attorney general.
Filing Fees
Unlike Washington and Colorado, California authorizes the attorney general to impose filing fees of $1,000 for principal place of business filers or $500 for net sales threshold filers. Whether the attorney general will elect to impose these fees remains to be seen.
Confidentiality Protections
Filed materials are exempt from California's Public Records Act, but the attorney general may share filings with the Federal Trade Commission or the U.S. Department of Justice. The attorney general is also permitted to disclose filed materials with other state AGs that have enacted equivalent laws but must provide filers with at least five business days' notice before doing so.
No Waiting Period
Importantly, like Washington and Colorado, and unlike the federal HSR Act, the Act does not impose a waiting period before parties can close the transaction.
Penalties for Non-Compliance
The Act authorizes the attorney general to impose civil penalties for non-compliance. After written notice and a three-business-day cure period, the attorney general may impose a penalty of up to $25,000 per day of noncompliance.
Key Takeaways
- Transacting parties should determine whether the Act applies and ensure they can meet the one-business-day filing deadline.
- With three states now having baby HSR laws, parties should review all applicable state filing requirements.
- Parties should expect more states to follow as bills are pending in multiple other states.
For more information, please contact Scott Claassen, Jeetander Dulani, Nicci Warr, Heather Franco or the Stinson LLP contact with whom you regularly work.
