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Washington and Colorado are set to become the first states to substantially adopt the Uniform Antitrust Pre-Merger Notification Act. 

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Beginning July 27, certain companies and individuals will be required to submit electronic copies of their Hart-Scott-Rodino Act filings with the Washington state attorney general.

Barring a constitutional referendum, a similar requirement will go into effect in Colorado on Aug. 6.

This is likely only the beginning of a growing trend of premerger regulation at the state level.

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Earlier this year, Washington state enacted a version of the nascent Uniform Antitrust Pre-Merger Notification Act (the Uniform Act), which is slated to take effect on July 27.<a href="#_ftn1" id="_ftnref1">[1]</a> The Uniform Act will require companies or individuals who file a federal Hart-Scott-Rodino (HSR) Act premerger notification to contemporaneously file an electronic copy with the Washington attorney general’s office if the company or individual: (1) has its principal place of business in Washington; (2) has (or controls an entity that has) annual net sales of goods or services involved in the transaction of at least 20 percent of the HSR filing threshold (i.e., $25.28 million, 20 percent of the current minimum HSR threshold of $126.4 million); or (3) is a healthcare provider or provider organization.<a href="#_ftn2" id="_ftnref2">[2]</a> Closing a transaction subject to the Uniform Act without submitting the required notification could result in civil penalties of up to $10,000 per day of noncompliance.

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Colorado will likely join Washington and become the second state to implement a version of the Uniform Act. As early as Aug. 6,<a id="_ftnref3" href="#_ftn3">[3]</a> those who submit an HSR filing must contemporaneously file an electronic copy with the Colorado attorney general’s office if they: (1) have their principal place of business in Colorado; or (2) have (or control an entity that has) annual net sales of goods or services in excess of at least 20 percent of the HSR filing threshold.<a id="_ftnref4" href="#_ftn4">[4]</a> As with Washington’s version of the Uniform Act, failure to comply could result in civil penalties of up to $10,000 per day of noncompliance.

More states are likely to follow the lead of Washington and Colorado. Currently, versions of the Uniform Act have been introduced in California, Hawaii, Nevada, Utah, West Virginia, and the District of Columbia.<a href="#_ftn5" id="_ftnref5">[5]</a> New York Senate Bill 335, which passed in the state Senate in June 2025 and remains pending in the Assembly, would apply to a broader set of transactions than does the Uniform Act.<a href="#_ftn6" id="_ftnref6">[6]</a> If enacted, this bill would subject any person “conducting business in the state” who is also subject to a federal HSR filing to a premerger notification requirement with the New York attorney general.<a href="#_ftn7" id="_ftnref7">[7]</a> In addition to these laws of general applicability, 34 states plus the District of Columbia already have premerger notification requirements for certain transactions involving healthcare entities.<a href="#_ftn8" id="_ftnref8">[8]</a> The filing requirements are a patchwork, and the waiting period the parties must observe varies from state to state. Finally, California also requires premerger filings for certain transactions involving retail grocery stores and retail drug stores (i.e., pharmacies) with a physical presence in California.<a href="#_ftn9" id="_ftnref9">[9]</a>

Transacting parties need to keep apprised of rapidly developing state antitrust legislation in order to ensure compliance. These state laws may delay closing if all relevant filings are not made timely, or worse, subject the transacting parties to substantial fines for noncompliance. Antitrust counsel should be involved early in diligence to ensure that all required filings are identified and made correctly and timely.

The authors would like to give special thanks to Summer Associate Stef Pousoulides for her contributions to this blog.

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<a id="_ftn1" href="#_ftnref1">[1]</a> S.B. 5122, 69 Leg., 2025 Sess. (Wash. 2025), available at <a href="https://lawfilesext.leg.wa.gov/biennium/2025-26/Pdf/Bills/Senate%20Passed%20Legislature/5122.PL.pdf?q=20250408084052" target="_blank" rel="noreferrer noopener">https://lawfilesext.leg.wa.gov/biennium/2025-26/Pdf/Bills/Senate%20Passed%20Legislature/5122.PL.pdf?q=20250408084052</a>.

<a href="#_ftnref2" id="_ftn2">[2]</a> Washington’s new premerger notification requirement adopts the definition of a healthcare provider or organization from Wash. Rev. Code § 19.390.020. This requirement is unique to Washington’s version of the Uniform Act.

<a href="#_ftnref3" id="_ftn3">[3]</a> Colorado’s law will go into effect on Aug. 6 if no state constitutional referendum in opposition to the bill is initiated. If such a referendum is initiated, the effective date would be delayed until after the general election in November 2026, when Coloradans would vote on the referendum.

<a id="_ftn4" href="#_ftnref4">[4]</a> S.B. 25-126, 75th Gen. Assemb., 1st Reg. Sess. (Colo. 2025), available at <a href="https://leg.colorado.gov/sites/default/files/2025a_126_signed.pdf" target="_blank" rel="noreferrer noopener">https://leg.colorado.gov/sites/default/files/2025a_126_signed.pdf</a>.

<a id="_ftn5" href="#_ftnref5">[5]</a> See S.B. 25, 2025-26 Leg., Reg. Sess. (Cal. 2025); S.B. 348, 33d Leg., Reg. Sess. (Haw. 2025); S.B. 218, 83d Leg., Reg. Sess. (Nev. 2025); H.B. 466, 2025 Leg., Gen. Sess. (Utah 2025); H.B. 2110, 2025 Leg., Reg. Sess. (W. Va. 2025); S.B. 32, 2025 Leg., Reg. Sess. (W. Va. 2025); B. 26-0030, 26th Council (D.C. 2025); see also Kaitlin Wolff, Antitrust Pre-Merger Notification Act: Bill List, Unif. Antitrust L. Comm’n, <a href="https://www.uniformlaws.org/committees/community-home?CommunityKey=6bf5d101-d698-4c72-b7c1-0191302a6a95" target="_blank" rel="noreferrer noopener">https://www.uniformlaws.org/committees/community-home?CommunityKey=6bf5d101-d698-4c72-b7c1-0191302a6a95</a>.

<a href="#_ftnref6" id="_ftn6">[6]</a> S.B. 335, 2025 Gen. Assemb., Reg. Sess. (N.Y. 2025).

<a href="#_ftnref7" id="_ftn7">[7]</a> There are a number of limited exemptions. See id. § 340(11)(b).

<a id="_ftn8" href="#_ftnref8">[8]</a> Sarah Jaromin, The Evolving Landscape of State Health Care Transaction Laws, The Nat’l Conf. of State Legislatures (Aug. 19, 2024), <a href="https://www.ncsl.org/health/the-evolving-landscape-of-state-health-care-transaction-laws" target="_blank" rel="noreferrer noopener">https://www.ncsl.org/health/the-evolving-landscape-of-state-health-care-transaction-laws</a>.

<a href="#_ftnref9" id="_ftn9">[9]</a> See Cal. Corp. Code § 14700.

State-Level Merger Scrutiny Grows: Washington, Colorado Lead Expansion of State Premerger Notification Laws