California has enacted a sweeping new premerger notification law that will significantly expand the state’s visibility into M&A activity. On Feb. 10, 2026, Governor Gavin Newsom signed the California Uniform Antitrust Premerger Notification Act (SB 25), making California the third state—after Washington and Colorado—to adopt a broad, cross‑industry premerger filing regime. The law becomes effective Jan. 1, 2027. Previously, notifications were required only of healthcare, retail grocery and retail drug transactions.

Key requirements

SB 25 is modeled on the Uniform Law Commission’s draft legislation and ties its applicability to federal Hart‑Scott‑Rodino (HSR) filings. A company must submit its HSR filing to California within one business day if either of the following thresholds is met:

  • The company’s principal place of business is in California; or
  • The company or its subsidiaries have more than $26.8 million in annual California net sales of the goods or services involved in the transaction.

Further guidance on the filing mechanism and threshold calculations is expected later in 2026.

Fees and penalties

California diverges from other states by imposing:

  • Filing fee: up to $1,000
  • Civil penalties: up to $25,000 per day for non‑compliance

Despite these requirements, there is no mandatory waiting period before closing.

Implications for companies

SB 25 is expected to have a broader impact than similar laws in other states due to California’s economic scale. Companies with California operations or sales above the $26.8 million threshold should anticipate:

  • Earlier and more frequent state‑level scrutiny of transactions
  • Automatic access by the California Attorney General (AG) to key HSR information
  • Potential multistate review, as the law permits sharing filings with Washington, Colorado and any future states that adopt the premerger law

Enforcement posture

California officials have signaled that the intent is to receive filings concurrently with federal agencies. Nonetheless, SB 25 aligns with a broader trend of increasing state activism in merger review, particularly where state interests or consumers may be affected.

What companies should do now

  • Assess California nexus early in deal planning
  • Incorporate SB 25 filings into transaction timelines beginning January 2027
  • Evaluate potential for increased state AG engagement, especially for deals involving significant California sales
  • Monitor forthcoming guidance on filing procedures and thresholds

If you have any questions, please contact Jay at 202-778-3021 or jlevine@porterwright.com