Washington State Enacts Broad Antitrust Premerger Notification Law

On 4 April 2025, Washington became the first state to enact a broad, industry-agnostic merger control regime. Under the new law, parties submitting premerger notification filings under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (HSR) must simultaneously submit their HSR filings to the Washington attorney general (AG) if they meet certain local nexus requirements or are a healthcare provider or provider organization. The law will take effect on 27 July 2025.

While many states (including Washington) have recently established notification requirements for healthcare transactions, the new Washington law is unique in its broad application to deals in any sector. Together with the new HSR rules, which took effect in February 2025, the law could increase regulatory costs and antitrust scrutiny for reportable transactions, particularly for companies with a significant presence in the state. More broadly, the legislation continues a trend of heightened state-level merger review, and underscores that states remain an important factor in the US antitrust enforcement landscape.

Washington Premerger Notification Law

On 4 April 2025, Washington Governor Bob Ferguson signed into law the Uniform Antitrust Premerger Notification Act (the Act). The Act will take effect on 27 July 2025 and apply to any HSR filings made on or after that date.

Thresholds 

The Act requires any “person”¹ submitting an HSR filing to contemporaneously file an electronic copy of the HSR form with the Washington AG if any of the following applies:

• The person’s principal place of business is in Washington.
• The person, or any entity it directly or indirectly controls, had annual net sales in Washington of goods or services involved in the transaction of at least 20% of the HSR filing threshold (under the current threshold of US$126.4 million, this would mean local annual net sales of at least US$25.28 million).
• The person is a healthcare provider or provider organization (as defined in RCW 19.390.020) conducting business in Washington.

Documents

If the “principal place of business” threshold is met, or if the AG otherwise requests, then the filing party must also submit documentary attachments to the HSR form, including the transaction agreement and any other agreements between the parties, audited financials for the most recent year, and documents analyzing the transaction with respect to various competition issues.

Confidentiality

Under the Act, filings and related materials are confidential and exempt from public disclosure, other than in connection with certain administrative or judicial proceedings, subject to protective order. The AG may also disclose information to the Federal Trade Commission, US Department of Justice, or the AGs of other states that have adopted similar reciprocal legislation.

Penalties

Failure to submit filings required by the Act can trigger civil penalties of up to US$10,000 for each day of noncompliance.

Interplay With Washington Healthcare Notification Law

Like many states, Washington already has a premerger notification requirement on the books applicable to certain healthcare transactions. Under this law, both parties to “material change transactions” (mergers, acquisitions, or contracting affiliations) between two or more in-state hospitals, hospital systems, providers, or provider organizations must submit a written notice (Notice of Material Change) to the AG at least 60 days prior to closing.² This requirement applies to transactions involving an in-state and out-of-state entity where the latter generates US$10 million or more in healthcare services revenues from patients residing in Washington. The law also states that any provider or provider organization that conducts business in Washington and files an HSR form must provide a copy of the filing to the AG’s office in lieu of a Notice of Material Change.

The Act has a much broader scope, capturing HSR-reportable transactions in any industry, not just healthcare. HSR filings submitted under the Act by providers and provider organizations will be sufficient to satisfy the requirements under the healthcare transactions notification law, which will remain on the books. Note, however, that the definitions for “provider” and “provider organizations” do not specifically include hospitals or hospital systems. Therefore, absent additional guidance from the AG, hospitals and hospital systems that meet the thresholds under the Act may need to submit a copy of the HSR form and a Notice of Material Change.

What Happens Next? Premerger Notification in Other States

The Act is based on model legislation from the Uniform Law Commission, which adopted the Uniform Antitrust Pre-Merger Notification Act in July 2024. Similar bills have been introduced in Colorado, Hawaii, Nevada, Utah, West Virginia, and the District of Columbia. One of the goals of the model legislation is to “facilitate early information sharing and coordination among state AGs and the federal antitrust agencies” and encourage reciprocal adoption by states. As state AGs assume an increasingly significant role in US antitrust enforcement—including in the M&A context—the new Washington law could signal the beginning of a trend of heightened, industry-agnostic, state-level merger control.

What Should I Do Now?

In light of the new requirements under the Act, dealmakers should consider the following:

• Evaluating state-level merger control filings alongside HSR, global merger control, and foreign direct investment filing requirements as part of standard transaction diligence, as well as building these filing considerations into deal negotiations and documents, as appropriate.
• If an HSR filing is required, assessing potential filings under the Act, particularly where companies have a significant nexus to the state of Washington (in terms of principal location or local revenues).
• Closely monitoring developments in other states, including new regimes coming online or proposed amendments broadening the scope of existing requirements, and preparing for reciprocal sharing of filings between states with similar legislation.
• Assessing the impact of filings that may be required under the Act with respect to budget, timing, and the potential for increased visibility into business operations by regulators. 
• Assessing potential competitive impacts on local markets when evaluating transactions and how these effects are discussed in ordinary-course documents.

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Footnotes