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