Overview
Introduction
Counsel outside the United States considering transactions involving a US nexus must take into account the rapidly changing competition enforcement landscape in the US ongoing developments affect timing, burden, and risk making early premerger filing planning essential.
Recent updates to the Hart-Scott-Rodino Antitrust Improvements Act (HSR) filing rules significantly expanded documentation and disclosure requirements – particularly for foreign parties that must translate and quality-check materials. In parallel, the US state enforcement system, unfamiliar to some non-US attorneys, has become more active. Certain US states now require separate merger filings to review and potentially seek to block transactions or may coordinate merger challenges with federal agencies. Particular industries can trigger filings with other US federal agencies (for example, concurrent notice to the Department of Defense). The Federal Trade Commission (FTC) and the Antitrust Division of the US Department of Justice (DOJ) continue to set global benchmarks, influencing enforcement strategies well beyond US borders through their imposition of structural and behavioral remedies.
Complicating matters further, on February 12, 2026, a federal court vacated the FTC's 2024 overhaul of the HSR pre-merger notification requirements. For now, an appellate court has approved an administrative stay, preserving the new HSR rule until further briefing.
What follows in this article is an analysis of these developments and identification of the risks, timing considerations, and compliance steps that non-US practitioners must address.
Part 1 Change of HSR Filing Rule
In accordance with the applicable HSR rules, many transactions require premerger filing with the FTC and DOJ. The threshold is based partially on the size of the transaction, a figure that the FTC adjusts annually based on GDP (with the most recent minimum filing threshold announced on January 16, 2026, to be $133.9 million).
In February 2025, the HSR rule experienced its most substantial procedural update in decades. The changes significantly increased the scope of supporting documents required in HSR filings. The updated rule now demands that parties submit a broader set of transaction descriptions and business documents. While these changes apply to all filing parties, they pose significant challenges for companies and counsel outside the United States. Specifically, the rule requires filers to submit English translations of any foreign language document. Although the rule permits machine translation, parties need to verify the accuracy of such transactions and should not underestimate the time and cost of review.
Furthermore, the new HSR rule requires parties to provide more detailed descriptions of the products and capital structures. In horizontal-relationship deals, description of competing products or services and information regarding the top ten customers for the products or services are now required. In vertical relationship deals, information regarding the products or services supplied to or purchased from the other parties, and the top 10 customers or suppliers for each of them, are required. In addition, the scope of documents and information to be produced has expanded, for example, to include: (1) documents created by or sent to the "Supervisory Deal Team Lead," (2) periodic reports sent to CEOs regarding overlapping markets, (3) and identification of all officers and directors who are directors or officers of competitors in overlap markets.
Ongoing litigation has called into question whether the new HSR rule will remain in effect. As of this article's publication, the rule remains in place pending an administrative stay in the Fifth Circuit Court of Appeals. Further details provided below:
- On February 12, 2026, the US District Court for the Eastern District of Texas vacated the FTC's revised HSR rule nationwide. The court held that the agency exceeded its statutory authority under the Administrative Procedure Act, engaging in "arbitrary and capricious" rulemaking and finding that the benefits of the new rules do not outweigh their substantial costs.
- The FTC appealed to the US Court of Appeals for the Fifth Circuit on February 19, 2026, securing an administrative stay while the court considers the FTC's emergency motion for a stay pending appeal. Briefing proceeded on an expedited schedule.
- The new HSR rule remains in effect presently. Companies must comply until further notice from the Fifth Circuit.
Since the updated HSR form remains in effect, preparation compliance should begin long before the deal is signed, due to the more burdensome requirements. Once the deal starts to appear feasible, consulting legal counsel is essential to avoid unnecessary delays.
Part 2 State Merger Control and Additional Federal Agency Filing
While most non-US practitioners are familiar with the federal merger control process under HSR, fewer are aware that individual US states can impose their own merger review procedures and enforcement actions. The United States has a dual federal-state system, so even if a transaction complies with federal requirements, this does not preclude separate state enforcement (similar to the relationship between EU and member countries). In the US, state antitrust enforcement is increasingly influential.
State-Level Filing Requirements
State-level premerger notification regimes have expanded, particularly in healthcare transactions. Increasingly, many state premerger filing requirements operate parallel to federal HSR thresholds, though not always.
Healthcare Transactions
Several states require filings for certain healthcare-related deals, even when they fall below federal HSR thresholds (for example, including New York, California, Hawaii, Illinois and Massachusetts). For example, California's Office of Health Care Affordability expanded its review authority to include a broad range of transactions involving hospitals, physician groups, and other healthcare providers. Other states have strengthened oversight through procedural enhancements. On January 8, 2025, Massachusetts enacted legislation involving comprehensive revisions of its health care transaction notification process to enhance its healthcare sector review.
Beyond Healthcare
There is a growing trend toward state-level merger review outside the healthcare sector. Washington and Colorado enacted broader premerger notification requirements modeled on the Uniform Antitrust Premerger Notification Act structure, which applies to a wider range of industries. Indiana set broader premerger notification requirements on January 21, 2026. This trend will continue in multiple states. In fact, legislatures in California and the District of Columbia are considering similar requirements.
In addition, there are emerging requirements for specific sectors. For instance, most states require state Public Utility Commission's approval for certain transactions. California requires pre-merger filing in deals involving the retail grocery sector.
A greater number of transactions trigger complex multijurisdictional filing obligations. Parties should monitor the status of state-merger filing regulations. Relatedly, certain industries may require separate filings by additional federal agencies. In some instances, clients will be familiar with regulators they interact with in their industry. For example, filings are often required with the Federal Communications Commission (satellites, mobile phones, television,
radio, and other media industries), Federal Energy Regulatory Commission (energy utilities), and, as of 2024, the Department of Defense (with a broad scope of applicability).
State Enforcement in Coordination with Federal Agencies
State authorities often coordinate with the FTC or the DOJ in challenging transactions. In high-profile cases – such as the proposed Kroger-Albertsons supermarket merger – multiple states joined the FTC's lawsuit to block the deal, citing potential harm to competition and consumers. And as a relatively new development in the Kroger-Albertsons merger challenge, Colorado and Washington brought their own cases to block the merger, in addition to the FTC, meaning that the parties had to withstand challenges by multiple enforcement authorities.
Coordinated enforcement significantly increases litigation risk and deal uncertainty. Even if a federal agency declines to challenge a transaction, the interests of individual states may lead to a challenged transaction. In addition, the states and federal agencies may pursue challenging a transaction in parallel.
Remedying Investigated Transactions
The FTC or DOJ may require parties to implement specific measures before allowing a deal to proceed, if they identify competitive concerns in a transaction. These measures may be structural – involving divestitures of business units or assets – or behavioral, imposing contractual or behavior obligations on how parties operate. Because US remedies are advanced and closely observed, foreign deal teams should analyze US cases to anticipate possible remedies in other jurisdictions.
Structural Remedies
Structural remedies aim to eliminate competitive concerns by removing overlapping assets or capabilities from the merged entity. Structural relief is the favored approach for FTC and DOJ because it involves a permanent change to the market structure, requires less ongoing
monitoring, and reduces the risk of future non-compliance. Based on recent trends, structural relief is preferred in sectors which have a direct impact on consumers. For example,
Constellation Energy Corporation's proposed acquisition of Calpine Corp. would have created the US's largest producer of electricity. Although the combined share of parties would be below 30%, the DOJ raised antitrust concerns with an emphasis on portfolio effects. The DOJ approved the deal conditioned on the divestiture of six of Calpine's generating assets.
Behavioral Remedies
Behavioral remedies, which take the form of an injunction requiring the merged entities to refrain from taking certain actions or affirmatively take other actions, may preserve competition but are harder for antitrust agencies to enforce. For example, while not a merger case, in the Google Search litigation, the US district court determined that Google unlawfully maintained a monopoly in general search service and text advertising. The central issue was Google's strategy of paying billions of dollars to secure default search engines with device manufactures and browser developers, excluding competitors. DOJ explored the possibility of requiring Google to divest its Chrome browser as part of antitrust remedy, although the court ultimately dismissed this proposal. Instead, the court entered a behavioral remedy, prohibiting Google from entering into the kinds of agreements that gave rise to the alleged anticompetitive effects. This case is notable because the DOJ proposed a structural remedy – the divestiture of Chrome – indicates a substantial favor toward structural remedies over behavior ones, even in a conduct case. While structural remedies have been generally preferred, behavioral remedies remain a key part of US antitrust enforcers' toolkit.
Recent instances have recognized broader forms of competition, beyond mere profit-driven rivalry, calling for flexible, tailored behavioral measures to align with such competitive dynamics. For example, Omnicom Group Inc., the third largest media buying advertising agency, recently acquired the Interpublic Group of Companies, Inc., the fourth largest one. Notably, the FTC raised concern that coordination among advertising agencies to suppress spending on publications with disfavored political or ideological viewpoints threatened to distort competition between advertising agencies and public discussion and debate. The FTC accepted a consent order imposing restrictions that prevent Omnicom from engaging in coordination with other agencies to direct advertising away from media publishers based on the publisher's political or ideological viewpoints.
Conclusion
Recent changes in US merger control – from expanded HSR filing requirements to growing state-level enforcement and evolving remedy practices – underscore the need for foreign counsel to stay alert. These developments can directly increase compliance burdens for cross-border deals and introduce procedural elements unfamiliar outside the US. Importantly, trends in US remedies, while shaped by domestic enforcement priorities, often influence how regulators in the world design their own interventions. By monitoring US practices closely, international deal teams can better anticipate regulatory challenges and align their strategies with emerging global standards.
