New HSR Rules and 2023 Merger Guidelines – Here to Stay?

The past two weeks saw major developments in the US merger clearance process. On February 10, 2025, the Federal Trade Commission’s (FTC) revised Hart-Scott-Rodino (HSR) rules and new filing forms went into effect, marking the most significant overhaul of HSR reporting requirements in 45 years. Then, on February 18, 2025, FTC Chairman Andrew Ferguson issued clear support for the 2023 Merger Guidelines, signaling his commitment to the merger review approach set by the Biden Administration. Many questioned whether these significant Biden-era moves would carry over, but Ferguson’s recent statements suggest that the reforms are here to stay.

The revised HSR reporting rules require merging parties to submit more transaction and industry-related documents, narrative descriptions on deal rationale and market overlaps, and full lists of buyers’ key personnel and investors, making the process more complex and time-consuming.¹ On the day the new rules took effect, Ferguson reaffirmed the FTC’s support, stressing that the new rules will improve efficiency and reduce long-term costs for transacting parties despite increasing initial burdens. Ferguson stated, “the old rules were passed nearly 50 years ago, and updates were long overdue.”² Critics have argued the new requirements could increase preparation time and expense. But Ferguson contends, as former Chair Lina Khan did, that the reforms will ensure enforcers have the information necessary to quickly identify anticompetitive mergers and clear beneficial deals faster. He maintains the new rules are “a win-win for all parties and will lower future costs for firms and the government.”³

Like the new HSR rules, the 2023 Merger Guidelines indicate a possible new era of stricter merger enforcement.⁴ The revised guidelines lower the threshold for when a merger is presumptively anticompetitive, emphasize the danger of vertical mergers, and give greater considerations to labor markets. Ferguson commented that “[f]or the foreseeable future…the FTC will use the 2023 Merger Guidelines.”⁵ Critics contend the guidelines sanction excessive government interference with properly functioning markets. Indeed, Ferguson has conceded that “[n]o guidelines are perfect,” but he nonetheless contends that the FTC should “prize stability and disfavor wholesale rescission” and avoid “constant turnover.”⁶ Omeed Assefi, Acting Assistant Attorney General for the DOJ Antitrust Division, concurred in a separate statement.⁷ Support for the new HSR Rules and the 2023 Merger Guidelines signals resistance to major changes in merger enforcement.

Despite the introduction of a bill to overturn the HSR rules by Representative Scott Fitzgerald and opposition to the 2023 guidelines, the Biden-era changes are likely to remain in effect. Transacting parties should assume that both reforms will remain and contact antitrust counsel to ensure compliance with the current regulatory landscape.

¹  Williams H. Stallings et al., Final FTC Rule Enacts Fundamental Changes to HSR; Will Complicate Merger Filings, Mayer Brown (October 11, 2024), https://www.mayerbrown.com/en/insights/publications/2024/10/final-ftc-rule-enacts-fundamental-changes-to-hsr-will-complicate-merger-filings.

²  Andrew N. Ferguson (@AFergusonFTC), X (February 10, 2025), https://x.com/AFergusonFTC/status/1889104725624168453?prefetchTimestamp=1739557395712&mx=2.

³ Andrew N. Ferguson (@AFergusonFTC), X (February 10, 2025), https://x.com/AFergusonFTC/status/1889104730128834995.

⁴  William H. Stallings et al., New Merger Guidelines Reflect Agencies’ Aggressive Enforcement Stance, Mayer Brown (December 20, 2023), https://www.mayerbrown.com/en/insights/publications/2023/12/new-merger-guidelines-reflect-agencies-aggressive-enforcement-stance.

⁵  Andrew N. Ferguson, Merger Guidelines, Federal Trade Commission (February 18, 2025), https://www.ftc.gov/system/files/ftc_gov/pdf/ferguson-memo-re-merger-guidelines.pdf?utm_source=substack&utm_medium=email.

⁶ Id.

⁷ Omeed Assefi, Use of the 2023 Merger Guidelines, the Department of Justice (February 18, 2025), https://www.justice.gov/atr/media/1389861/dl?inline.