Washington and Colorado Enact Groundbreaking State-Level Merger Notification Requirements, With Other States Likely To Follow | Snell & Wilmer

Washington was the first state to adopt the Uniform Antitrust Pre-Merger Notification Act. Signed into law in April 2025 and effective as of July 27, 2025, the Washington law establishes new premerger filing requirements for transactions that meet both federal and state-specific criteria. Washington’s law applies only to transactions that already are subject to federal Hart-Scott-Rodino (HSR) reporting, but it also layers on additional obligations where certain Washington nexus thresholds are met.

Washington’s pre-merger notification obligations are triggered if: (1) a party maintains its principal place of business in Washington, (2) the party’s — or any entity it directly or indirectly controls — net sales of goods or services in Washington, which are related to the transaction are at least 20 percent of the HSR filing threshold ($126.4 million in 2025); or (3) a party is a healthcare provider or organization conducting business in Washington. These thresholds ensure that only transactions with a meaningful in-state economic connection are subject to additional reporting.

Filing parties with their principal place of business in Washington must provide a complete copy of the federal HSR filing, including all exhibits and attachments submitted to federal agencies. Otherwise, the filing party need only include all exhibits and attachments at the request of the Attorney General.

Exhibits and attachments to the HSR filing include Transaction Information and Business Documents (formerly referred to as 4(c) and 4(d) documents), which often contain internal analyses of competition, market share, and strategic rationale. The law requires that submissions be made contemporaneously with the federal HSR filing, with no separate state waiting period imposed.

To preserve confidentiality, Washington’s statute expressly exempts submitted materials from public disclosure under the state’s public records laws. Disclosure is allowed only in the context of official proceedings and subject to protective orders. The statute also authorizes — but does not require — the Washington Attorney General to share filings with the Federal Trade Commission, the Department of Justice, or Attorneys General in other states with substantially similar premerger laws. This discretionary sharing mechanism is designed to support coordinated multi-jurisdictional enforcement efforts while maintaining strict confidentiality protections.

To promote compliance, the law includes an enforcement mechanism that allows for civil penalties of up to $10,000 per day for failure to file. This underscores the need for deal teams to incorporate Washington’s requirements into their closing checklists, particularly where either party has significant operations or revenue within the state.

Colorado Senate Bill 25-126, the Uniform Antitrust Pre-Merger Notification Act, was signed into law by Governor Jared Polis on June 4, 2025, and becomes effective on August 6, 2025.

This legislation marks a shift in Colorado’s antitrust framework, creating industry-neutral notification obligations that mirror the federal HSR regime but operate independently at the state level. Unlike Colorado’s prior sector-specific rules, this Act applies across all industries, but only to transactions that are already subject to federal HSR reporting.

Under the statute, a qualifying party must provide a copy of its HSR filings to the Colorado Attorney General contemporaneously with its federal submissions, if the transaction in question meets one of the state’s nexus triggers.

Like in Washington, a party must provide a copy of its HSR filing to the Colorado Attorney General if: (1) a party to the transaction maintains its primary business headquarters within Colorado; or (2) a party to the transaction — or any entity it directly or indirectly controls — has annual net sales in Colorado related to the proposed transaction equal to or greater than 20 percent of the current HSR size-of-transaction threshold. As of 2025, with HSR thresholds at $126.4 million, the Colorado revenue trigger would equal $25.28 million in in-state sales.

Unlike Washington, Colorado does not include a third trigger for healthcare providers or organizations. Colorado’s prior sector-specific rules, however, already imposed disclosure requirements on certain healthcare organizations. 

Also, unlike Washington, filing parties are generally required to submit an electronic copy of the complete HSR filing, including all exhibits and attachments. This ensures the Attorney General has access to the same substantive materials being reviewed by federal regulators.

Recognizing the commercially sensitive nature of merger filings, Colorado’s Pre-Merger Notification Act includes confidentiality protections. All materials submitted to the Colorado Attorney General under this law are confidential and exempt from public disclosure under the Colorado Open Records Act. Disclosure is permitted only in connection with administrative or judicial proceedings and then only under appropriate protective orders.

Like its Washington analog, Colorado’s Pre-Merger Notification Act also authorizes — but does not require — the Attorney General to share information with the Federal Trade Commission, the U.S. Department of Justice Antitrust Division, and Attorneys General in other states that have adopted substantially similar legislation. It also authorizes the Colorado Attorney General to seek civil penalties of up to $10,000 for each day a party remains out of compliance.

Strategic Context and National Developments

Washington and Colorado’s recent legislation reflect a broader trend among states seeking to play a more active role in merger oversight. The Uniform Law Commission adopted the Uniform Antitrust Pre-Merger Notification Act in July 2024. This model legislation provides a framework that states can adopt to enhance merger enforcement capabilities, while promoting interstate consistency.

More states are following Washington and Colorado’s example. California, Hawaii, West Virginia, and the District of Columbia have introduced legislation that would apply to HSR-reportable transactions where a party has either its principal place of business in the state or derives at least 20 percent of its U.S. revenue from in-state operations. Notably, California’s proposed legislation includes a separate filing fee of $1,000 where a party has its principal place of business in California or $500 where the party meets the revenue threshold.

Utah and Nevada similarly introduced legislation largely mirroring Washington, Colorado, and the Uniform Antitrust Pre-Merger Notification Act. However, both bills failed to pass in the most recent legislative sessions.

New York recently proposed legislation that goes even further than the Uniform Antitrust Pre-Merger Notification Act. It requires any party conducting business in the state that is required to submit an HSR filing to contemporaneously provide the same notice and documentation, in its entirety, to the Attorney General.

Compliance and Risk Mitigation Considerations for Businesses

For companies involved in M&A activity, these new laws introduce both strategic and operational considerations. First, dealmakers should consider incorporating potentially applicable state-law filing obligations into the due diligence process alongside HSR and other regulatory assessments, such as international merger control and foreign direct investment rules. State-level filing requirements could also be reflected in transaction timelines and closing conditions to help avoid last-minute compliance risks.

Filing parties also should account for the potential resource implications of the new law, including legal review, administrative processing, and possible engagement with State Attorneys General. Although the state laws do not impose waiting periods or clearance requirements, parties should anticipate increased scrutiny of transaction rationales, competitive effects, and state-specific market dynamics.

Companies may also want to revisit their internal document generation practices and carefully evaluate whether ordinary-course business materials contain language discussing competitive effects, market strategy, or industry dynamics — especially where such documents may be included in HSR filings and thus disclosed to state authorities.

Companies should consider an assessment of all pending and upcoming transactions for pertinent state jurisdictional triggers and ensure that transaction schedules accommodate any new filing obligations. Future planning could include the development of internal screening protocols to flag, early in the transaction lifecycle, connections to states with enacted legislation, or bills in the legislative pipeline.

Moreover, general counsel and compliance teams should consider formalizing relationships with antitrust counsel familiar with state laws and establishing standardized procedures for managing multi-jurisdictional merger filings. Training programs may be necessary to educate deal teams on the evolving compliance landscape.

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