With the passage of SB 25, California becomes the third state to pass a state-level “mini-HSR” regime, joining Washington and Colorado, which enacted similar legislation in 2025. The Act applies to HSR notifications filed on or after January 1, 2027.~~On February 10, California Governor Gavin Newsom signed SB 25 into law.[1]  SB 25—the California Uniform Antitrust Pre‑Merger Notification Act—requires certain Hart‑Scott‑Rodino (HSR) filers to submit a copy of their federal premerger notification materials to the California Attorney General.  Unlike the HSR Act, a California State filing does not trigger a waiting period that suspends the parties from closing their transaction, but the filing is mandatory and designed to create an early, streamlined avenue for state review and coordination.  With the passage of SB 25, California becomes the third state to pass a state-level “mini-HSR” regime, joining Washington and Colorado, which enacted similar legislation in 2025.  The Act applies to HSR notifications filed on or after January 1, 2027.[2]~~The bill is based on model antitrust legislation published by the Uniform Law Commission and is designed to align state practice with federal HSR procedures rather than create a wholly independent state review regime.  While the California Law Revision Commission has advanced broader antitrust proposals on single‑firm conduct and concerted action,[3] and continues to consider broader reform on mergers and acquisitions, SB 25 instead focuses narrowly on premerger notification procedures tied to HSR filings.  SB 25 therefore seeks to improve process and coordination, not to redefine substantive merger standards.~~California Attorney General Rob Bonta previously endorsed SB 25, emphasizing that the measure would provide “upfront access to federal merger filings,” “facilitate early information sharing and coordination,” and include “strong confidentiality provisions,” with the stated aim of streamlining merger evaluation for both the California Department of Justice (CA DOJ) and businesses.  This endorsement suggests the state plans to coordinate, not duplicate, federal merger review.~~SB 25’s Requirements, Protections, and Penalties~~SB 25 requires HSR filers to submit a complete electronic copy of the HSR form to the CA DOJ when either of the following is true:~~The filing party must also submit a complete electronic copy of the HSR form to the CA DOJ contemporaneously—at the latest, within one business day of the federal filing.  If the filing party’s principal place of business is in California, the submission must include a complete electronic copy of any “additional documentary material” filed with the HSR form.  And if the obligation to file is triggered by meeting the California sales threshold (rather than by maintaining a principal place of business in California), the CA DOJ may request the additional documentary material, and the filer must provide it within seven days of the request.[5]~~SB 25 enables the Attorney General to impose filing fees of $1,000 if the filing person has its principal place of business in California or $500 if the filing person had annual net sales in California of the goods or services involved in the transaction of at least 20% of the prevailing federal HSR filing threshold.  The fees are deposited into the Attorney General’s antitrust account.[6]~~The Attorney General must provide a secure means to receive and store submitted materials. [7]~~SB 25 provides robust confidentiality protections that prohibit the CA DOJ from making any component of the HSR form public; exempt these materials from disclosure under California’s public‑records law, aligning with HSR confidentiality norms; and permit disclosure only under protective order in an administrative or judicial proceeding where the proposed merger is relevant.[8]  However, SB 25 does allow the CA DOJ to share information with the Federal Trade Commission, the United States Department of Justice, and with other states that have adopted the ULC’s Uniform Antitrust Pre-Merger Notification Act (or substantively equivalent legislation) and that provide confidentiality assurances at least as protective as those in the uniform act.[9]  For reciprocity‑based disclosures to other states, the CA DOJ must provide at least five business days’ advance notice to the submitting party before making a disclosure.~~After written notice and a three‑business‑day cure period, the Attorney General may impose or seek to impose civil penalties of up to $25,000 per day for failure to submit the required materials or to respond timely to a request for additional documentary material.[10]