‘Mini-HSR’ Acts Take Effect in Washington and Colorado, with Similar Legislation Pending in Other States

Colorado and Washington state recently became the first states to adopt their own smaller versions of the Hart-Scott-Rodino Antitrust Improvements (HSR) Act. These “mini-HSR” state laws require certain parties that submit premerger filings to the federal government under the HSR Act to contemporaneously submit the same filings to state attorney general offices. More US jurisdictions are expected to enact similar legislation soon, continuing a trend of enhanced state scrutiny of mergers and acquisitions.

Previously, many states adopted healthcare-specific premerger notification laws, but these new statutes apply across all sectors and industries. Some key takeaways from these recent legislative efforts include the following:

• State legislatures are modeling their “mini-HSR” acts on the Uniform Antitrust Pre-Merger Notification Act (UAPNA), [1] model legislation published by the Uniform Law Commission (ULC), a nonprofit group that promotes nonpartisan and uniform state legislation
• The UAPNA requires that merging parties contemporaneously forward a copy of their HSR filings to applicable state governments
• Earlier this year, Washington state and Colorado approved their own “mini-HSR” laws that are heavily based on the UAPNA and started to apply to HSR filings on July 27, 2025 and August 6, 2025, respectively
• California, Hawaii, Nevada, Utah, West Virginia, and the District of Columbia have proposed their own premerger notification bills based on the UAPNA, and a further state—New York—has proposed its Twenty-First Century Antitrust Act, a law that seeks to broadly reform New York’s current antitrust regime and includes more expansive premerger notification provisions than the UAPNA

The Uniform Antitrust Pre-Merger Notification Act

The UAPNA provides states with a mechanism to receive the same information and notice that the federal agencies receive when parties file under the HSR Act. Below is a table outlining the key provisions included in the UAPNA:

Washington and Colorado’s ‘Mini-HSR’ Laws

Washington and Colorado are the only states that have enacted the UAPNA to date. Washington’s mini-HSR law [2] was passed on April 4, 2025, with an effective date of July 27, 2025, and Colorado’s mini-HSR law [3] was passed on June 4, 2025, with an effective date of August 6, 2025.

Under both states’ laws, any of the following circumstances triggers a filing requirement by a party to an HSR-reportable transaction:

1. The party has its principal place of business in the state; or
2. The party does not have a principal place of business in the state, but generates annual net sales of the goods or services involved in the transaction of at least 20% of the HSR Act’s size-of-transaction threshold. (The current HSR threshold is $126.4 million, meaning the current Washington and Colorado filing threshold is $25.28 million, subject to annual adjustment).

Under the first trigger, if a party filing an HSR Act notification has a principal place of business in Colorado or Washington, that party must submit its HSR filing to that state AG. While neither state law defines “principal place of business,” a comment to the UAPNA defines the term as “the place where a corporation’s officers, direct, control, and coordinate the corporation’s activities” (i.e., a corporation’s “nerve center”). [4]

The second trigger looks to each party’s in-state revenues “for goods or services involved in the transaction.” Recent guidance from the Washington AG suggests covered parties should look to the current HSR form to determine the “goods or services involved in the transaction.” [5] The form currently requires disclosure of the buyer’s and target’s “principal categories of products or services” and any current and known products of the parties that compete or could compete. [6] While the statutory language is not clear, an assessment of an overlap in products or services may be needed to determine whether the parties need to file.

In addition to the two separate triggers discussed above, Washington’s mini-HSR law, S.B. 5122, contains a further trigger that is absent from Colorado’s mini-HSR law—a “provider” or “provider organization,” as defined by Wash. Rev. Code § 19.390.020, must submit a mini-HSR filing to the Washington AG. Any provider or provider organization submitting a filing under S.B. 5122 does not need to separately file under Washington’s older, healthcare-specific mini-HSR law, Wash. Rev. Code § 19.390.010 et seq. Colorado has its own healthcare-specific mini-HSR law, C.R.S. § 6-19-101 et seq., that applies to transactions involving “licensed or certified hospitals.” However, Colorado’s mini-HSR law does not provide that a hospital submitting a filing under S.B. 25-126 does not need to separately file under the state’s healthcare-specific mini-HSR law.

Importantly, neither state law is suspensory, meaning that the parties do not need to wait for a waiting period to expire before closing (besides the waiting period under the HSR Act). Further, while these state mini-HSR laws in some cases require merging parties to forward materials accompanying HSR filings (e.g., so-called “D Documents” and copies of the executed merger agreement) to the AG, they do not explicitly require merging parties to forward information or materials submitted to the US Department of Justice or US Federal Trade Commission in connection with a Second Request merger investigation.

Pending State Premerger Notification Legislation

California, [7] Hawaii, [8] Nevada, [9] Utah, [10] West Virginia, [11] and the District of Columbia [12] have also proposed laws based heavily on the UAPNA, all of which are in different stages of each state’s respective legislative process.

While most pending and enacted state premerger notification legislation is based on the UAPNA, New York’s recently proposed antitrust law [13] represents a larger effort to reform New York’s Donnelly Act, the state’s 126-year-old antitrust law. As part of that reform, the bill contains premerger notification provisions that differ significantly from the UAPNA. S.B. 335 requires “any person conducting business” within New York to contemporaneously file the HSR form and any accompanying documents.

Further, unlike the UAPNA, the bill requires the New York AG to consider the transaction’s effects on labor markets and provides affected workers an opportunity to “meaningfully comment” on the proposed transaction within ten days of a filing. Finally, while S.B. 335’s confidentiality and penalty provisions are substantively the same as those in the UAPNA, the law contains no reciprocity provision encouraging coordination among other state AGs. The bill was passed by the New York State Senate and is currently in the Economic Development Committee in the New York State Assembly.

Looking Ahead

States are continuing to increase the capacity of their AGs as antitrust watchdogs, and businesses should expect more states to adopt these broad, industry-agnostic “mini-HSR” laws in the near future. Through these laws, state legislatures hope that their AGs will more easily identify transactions with potential antitrust issues and work more collaboratively with each other and federal antitrust agencies to probe those transactions.

Merging parties should expect that state “mini-HSR” filings will become the norm in numerous states and territories in the next few years. As these state mini-HSR laws become more common, merging parties should carefully consider how these statutes affect deal timing and closing risk, how the confidentiality statutes of those jurisdictions protect transaction-related information and materials, and how to account for these considerations in merger agreement negotiations.