California Joins Colorado and Washington in Passing “Mini HSR” Law
On February 10, 2026, California Governor Gavin Newsom signed Senate Bill 25 (SB 25) into law, launching California’s version of the Uniform Antitrust Premerger Notification Act (UAPNA). The new law establishes an obligation for each party to provide the state with a copy of its filing under the federal Hart-Scott-Rodino Antitrust Improvements Act of 1976 (“HSR Act”), where certain thresholds of interest established by the state are met. State Senator Thomas J. Umberg praised the bill’s passage, stating it would “creat[e] a fairer, more efficient merger review process that balances the needs of businesses while protecting consumers.”[1]
Key Takeaways
- Starting January 1, 2027, some companies that file under the federal HSR Act must also send a copy of their filing to the California Attorney General (AG) if they meet certain California-related thresholds.
- The law does not change the legal standard for reviewing mergers and the regime is not suspensory. Instead, it gives the California AG a mechanism to get information about certain transactions earlier in the federal review process.
- Companies planning HSR-reportable transactions should account for this additional filing when planning timing, costs, and document preparation.
- California’s law is similar to new requirements in Colorado and Washington, as summarized below, and is part of a trend of states seeking to take a more active role in evaluating transactions.
- The District of Columbia, Hawaii, Indiana, New York, West Virginia, and others are evaluating similar provisions.
Thresholds, Fees, and Penalties
Beginning January 1, 2027, SB 25 will require parties to HSR-reportable transactions to submit a copy of their HSR filings with the California AG if:
- The person has its principal place of business in California; or
- The person (including its controlled entities) has annual net sales in California of the goods or services involved in the transaction of at least 20% of the effective HSR transaction value threshold (i.e., at least $26.78 million under the threshold effective February 17, 2026).
Note that these thresholds are evaluated independently by and for each party, so unlike filing submissions to the federal government, it is possible that only one party is obligated to submit its filing in California.
For covered transactions, a copy of the HSR filing must be submitted to the AG within one business day of filing with the federal government. Principal-place-of-business filers must automatically provide a copy of the HSR Form and all attachments, while net sales-threshold filers must only submit attachments to the HSR Form upon the AG’s request within seven business days of receiving such request.
The California AG is authorized to charge a $1,000 fee for principal-place-of-business filers, and $500 for net sales-threshold filers. Both types of filers face civil penalties of up to $25,000 per day for failure to submit a necessary filing. There is a three business day grace period to cure noncompliance without penalty.
Confidentiality Protections
Under the law, the California AG is required to keep confidential the contents of the filing and the fact that the filing was made, and exempts filing materials from disclosure under the California Public Records Act. However, SB 25 does allow the California AG to share information with the Federal Trade Commission and U.S. Department of Justice Antitrust Division, and attorneys general of other states with substantively equivalent UAPNA acts and confidentiality protections. If the AG contemplates disclosure to another state, it must notify the filing person at least five business days before making the disclosure. Note this is different from the HSR Act that requires permission from the parties to discuss a filing with an interested state.
Practical Implications
- Evaluate California contacts and revenue thresholds during initial deal structuring (in addition to Colorado and Washington).
- Ensure that submission to the California AG is coordinated with the federal HSR filing.
- Anticipate that the California AG may issue follow-up questions or open an investigation for certain transactions of interest to the state, even if federal agencies do not. However, the AG does not have a regulatory mechanism to prevent the transaction from closing like the federal second request.
What Comes Next
The California AG’s Office is expected to issue guidance regarding implementation and filing procedures. Companies and deal counsel should monitor further developments, including any regulations or interpretive guidance clarifying the statute’s thresholds and timing requirements.
We are closely tracking developments and are available to discuss how SB 25 and the other mini HSR filings may affect transaction planning and antitrust strategy.
[1] Press Release, Senator Tom Umberg, Governor Signs First Bill of the Year – Umberg Antitrust Bill (Feb. 11, 2026).
[2] Cal. Bus. & Prof. Code, div. 7, pt. 2, § 16780 et seq..
[3] 2025 Colo. Sess. Laws 2366, S.B. 25-126, 2025 Reg. Sess. (Co. 2025).
[4] 2025 Wash. Sess. Laws 40, S.B. 5122, 69th Leg., Reg. Sess. (Wash. 2025).