Make Sure to CC the AG: Colorado and Washington Require State-Level Merger Notices | Dinsmore & Shohl LLP

Colorado and Washington have each enacted statutes modeled after the Uniform Law Commission’s Uniform Antitrust Pre-Merger Notification Act. Soon, both states will require parties to certain mergers and acquisitions (M&A) that are reportable to federal antitrust authorities under the Hart-Scott-Rodino (HSR) Act, to contemporaneously notify their state attorney general (AG) of the transaction.

Washington’s law went into effect on July 27, 2025, while Colorado’s law will take effect on August 6, 2025.

Who must notify?

Both Colorado and Washington statutes apply only to transactions that are reportable under the federal HSR Act. However, not all HSR-reportable deals require state-level notice. A notice obligation arises only if at least one of the following conditions is met:

• A party to the deal has its principal place of business in the state; OR
• A party (or an entity it directly or indirectly controls) has annual in-state sales of goods or services related to the transaction equal to at least 20% of the HSR filing threshold. Based on 2025 values, this would be approximately $25 million worth of in-state sales.[1]

Washington’s law adds on an additional requirement. Any HSR-reportable transaction involving a healthcare provider or healthcare provider organization doing business in the state must also be reported, regardless of whether the “20% sales” or “principal place of business” condition is met.

What must be filed? And when must it be filed?

In both states, parties must file a copy of the HSR form with the state attorney general at the same time as they submit it to federal antitrust authorities.

Colorado requires parties who meet either of the “principal place of business” or “in-state sales” prongs to also submit “additional documentary materials” included with the HSR filing.

Washington only requires the filing of “additional documentary materials” up front if a party meets the “principal place of business” prong.

Both states permit the AG to request “additional documentary material,” but the procedures differ slightly. In Colorado, any party required to file under the statute must provide the “additional documentary material” within seven days of the request by the AG. In Washington, the same seven-day deadline applies when the AG makes a request, but only if a party is required to file with the state AG based on either the “sales” or “healthcare” prong. 

Closing delay, fees and penalties

Importantly, neither state’s law imposes a waiting period that would delay closing. There are also no filing fees. However, the penalty for noncompliance is significant. Each state may impose civil penalties of up to $10,000 per day for failure to file the required materials.

Confidentiality protections

Both statutes include confidentiality provisions. The filings, including all additional documents, are protected from public disclosure. Disclosure, however, may be permitted in court or administrative proceedings under appropriate protective orders. Additionally, the laws permit the AG to share information with other state AGs, but only if the receiving state has adopted a similar law with confidentiality protections “at least as protective” as those in the Uniform Act. Each statute also requires that parties be given at least two business days of notice before any disclosure between AGs occurs.

What should dealmakers do now?

To prepare for these changes, dealmakers should consider the following steps:

• Update M&A checklists to flag Colorado and Washington filing triggers and plan for submission of HSR materials to state AGs.
• Reassess closing conditions to account for post-closing interventions by state AGs.
• Monitor developments in other states, as many states including New York, California, Hawaii, Nevada and West Virginia are actively considering similar legislation.
• Advise clients on penalty risks of up to $10,000 per day for failure to comply.

*Austin Liu is a summer associate and not yet licensed to practice law.

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