Colorado Enacts Uniform Antitrust Pre-Merger Notification Law

On 4 June 2025, Colorado became the second state—following the state of Washington—to enact a broad, state-level, industry-agnostic premerger notification regime. Under Colorado’s new law, any party that submits a filing under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (HSR) must also submit a copy of the filing to the Colorado Attorney General (AG), where certain thresholds are met. The new law is expected to take effect on 6 August 2025 and applies to transactions that trigger HSR reporting and have a relevant nexus to Colorado.

While Colorado, like many states, previously adopted notice requirements for certain healthcare transactions, the new Colorado law significantly broadens the scope of mandatory premerger filings to all industries. This development aligns with a growing trend toward enhanced state-level antitrust enforcement and coordination with federal authorities. Companies with significant operations in Colorado should understand the triggers under the new law and prepare for the prospect of additional regulatory scrutiny of deals at the state level.

COLORADO PREMERGER NOTIFICATION LAW

On 4 June 2025, Colorado Governor Jared Polis signed Senate Bill 25-126, the Uniform Antitrust Pre-Merger Notification Act (the Act), into law. The Act is expected to take effect on 6 August 2025 and apply to any HSR filings made on or after that date.

Thresholds

The Act requires any “person”¹ submitting an HSR filing to contemporaneously file an electronic copy of the HSR form with the Colorado AG if either of the following applies:

• The person’s principal place of business is in Colorado.
• The person, or any person it directly or indirectly controls, had annual net sales in Colorado of the goods or services involved in the transaction of at least 20% of the HSR filing threshold (under the current threshold of US$126.4 million, this would mean local annual net sales of at least US$25.28 million).

Documents

If the “principal place of business” threshold is met, or if the AG otherwise requests, then the filing party must also submit documentary attachments to the HSR form.

Confidentiality

Under the Act, filings and related materials are confidential and exempt from public disclosure, other than in connection with certain administrative or judicial proceedings, subject to protective order. The AG may, however, disclose or share information with the Federal Trade Commission, US Department of Justice, or the AGs of other states that have adopted substantively similar legislation.

Penalties

Failure to submit filings required by the Act can trigger civil penalties of up to US$10,000 for each day of noncompliance.

What Happens Next? Premerger Notification in Other States

The Act is based on model legislation from the Uniform Law Commission, which adopted the Uniform Antitrust Pre-Merger Notification Act in July 2024. Similar bills have been introduced in California, Hawaii, Nevada, Utah, West Virginia, and the District of Columbia. A broader premerger notification bill has also passed in New York but awaits approval by the New York State Assembly and New York governor. As state AGs assume an increasingly significant role in US antitrust enforcement—including in the mergers and acquisitions context—this new Colorado law is a further step toward broader state-level merger oversight and interjurisdictional cooperation.

What Should I Do Now?

In light of the new requirements under the Act, dealmakers should consider the following:

• Evaluating state-level merger control filings alongside HSR, global merger control, and foreign direct investment filing requirements as part of standard transaction diligence, as well as building these filing considerations into deal negotiations and documents, as appropriate.
• If an HSR filing is required, assessing potential filings under the Act, particularly where companies have a significant nexus to the state of Colorado (in terms of principal location or local revenues).
• Closely monitoring developments in other states, including new regimes coming online or proposed amendments broadening the scope of existing requirements, and preparing for reciprocal sharing of filings between states with similar legislation.
• Assessing the impact of filings that may be required under the Act with respect to budget, timing, and the potential for increased visibility into business operations by regulators.
• Assessing potential competitive impacts on local markets when evaluating transactions and how these effects are discussed in ordinary-course documents.

Please contact a member of our Antitrust, Competition, and Trade Regulation practice group for more information about how the Act may affect your transactions and guidance regarding dual compliance with HSR and state merger control requirements.