Alerts4.9.26
The Golden State Goes HSR: California’s SB 25 and the Rise of State-Level Pre-Merger Notification
Highlights
- On Feb. 10, 2026, California Governor Gavin Newsom signed Senate Bill 25 (SB 25) into law, making California the third — and by far the largest — state to adopt a broad, industry-agnostic “mini-HSR” pre-merger notification regime.
- Effective Jan. 1, 2027, the new law requires certain parties filing under the federal Hart-Scott-Rodino (HSR) Antitrust Improvements Act to submit a copy of their HSR filing to the California Attorney General (AG).
- California now joins Colorado and Washington, both of which enacted similar statutes in 2025, as states with general pre-merger notification laws modeled on the Uniform Law Commission’s Uniform Antitrust Pre-Merger Notification Act (UAPNA).
Importantly, SB 25 is non-suspensory, meaning it does not impose a waiting period or require state approval before closing. As California AG Rob Bonta has emphasized, the law is designed to provide “upfront access to federal merger filings” and “facilitate early information sharing and coordination” between state and federal antitrust officials, rather than to create a duplicative or independent review process.
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