Colorado's Pre-Merger Notification Act Update: What HSR Filers Must Do

What changed

Colorado's Uniform Antitrust Pre-Merger Notification Act already required parties in certain mergers to send the state Attorney General a copy of their federal Hart-Scott-Rodino (HSR) filing. HB 26-1427 rewrites several parts of that process. The filing window changes from "contemporaneous" with the federal filing to a clear one-business-day deadline after it. The AG must now provide a secure electronic system to receive and store the materials, and — new this year — must return or destroy them within 120 days after the underlying deal closes or any related legal proceeding ends, whichever is later.

The law also tightens how the AG shares information with other states that have adopted the same uniform act: before disclosing a filer's materials to another state's AG, Colorado's AG must now get that state's assurance it will keep the documents confidential, and must give the filer five business days' notice before any such disclosure (up from two). Finally, the bill writes a formal civil-penalty procedure into the statute for the first time in this detail: the AG must give written notice and a three-business-day opportunity to cure before seeking a penalty, capped at $10,000 per day of noncompliance.

Who is affected

You're in scope if your transaction already requires a federal HSR pre-merger notification to the FTC and DOJ, and it also meets Colorado's separate filing conditions spelled out in C.R.S. § 6-4.5-103(a) — the statute layers a state-level trigger on top of the federal one rather than replacing it. Because that state-level trigger isn't reprinted in the 2026 amendment (only the subsections the bill actually changed are), confirm your deal's status against the current text of § 6-4.5-103 or with M&A counsel rather than assuming HSR status alone is enough.

Once you know you're covered, the operational change is the clock: you now have one business day after your federal filing to get a complete electronic copy to the Colorado AG, not the prior "contemporaneous" standard. Deal teams that build HSR filing checklists should add a same-week Colorado AG filing step, and back-office counsel should note the AG's new 120-day materials-destruction clock in case a return-or-destroy confirmation is needed for the deal file.

How to comply, step by step

1. Determine whether your deal already requires a federal HSR filing, and if so, check whether it also meets Colorado's filing conditions under C.R.S. § 6-4.5-103(a) — consult the current statute or M&A counsel, since the exact state-level trigger isn't reprinted in the 2026 amendment text.
2. Calendar a one-business-day deadline to send the Colorado Attorney General a complete electronic copy of your HSR form once you file it federally.
3. Confirm the secure electronic submission channel the AG's office provides, since the amended law now requires the AG to maintain one.
4. If your deal materials remain on file with the AG after closing, track the 120-day clock for their return or destruction.
5. If the AG opens an enforcement inquiry, respond promptly to any written notice — you have three business days to cure before a civil penalty of up to $10,000 per day may be sought.

Frequently asked questions

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