Pre-2025 HSR rules to stay in place for now, new proposed changes expected by end of 2026

The Federal Trade Commission (FTC) has indicated it will propose a set of revised Hart-Scott-Rodino (HSR) premerger notification rules by the end of 2026. In the meantime, the pre-February 2025 rules will remain in place.

After the FTC’s overhaul of the HSR rules went into effect last year, it was subsequently challenged in court and struck down. The FTC appealed the decision; however, the United States Court of Appeals for the Fifth Circuit denied a motion to stay and the pre-February 2025 filing requirements went back into effect in March 2026.

With parties now filing under the traditional rules pending the appeal, the FTC has signaled that it intends to try again to revise the HSR requirements.

Background on HSR rules

On May 18, 2026, the FTC filed an unopposed motion requesting that its appeal be held in abeyance while the agency “seriously considers” whether to propose new changes to the HSR rules. The FTC’s motion explains that when the Fifth Circuit denied its request for a stay, the agency published a request for information seeking public input on the filing requirements.

The request for information suggested the FTC was contemplating another attempt at rulemaking, which the motion now confirms. While the public comment period closes on May 26, 2026, the agency’s filing acknowledges that it will need time to review the comments it receives and determine whether and what changes to propose. The FTC stated that its "current aim is to publish any notice of proposed rulemaking by the end of this calendar year."

Another round of rulemaking related to the HSR rules would be consistent with FTC Chair Andrew Ferguson’s comments that the February 2025 rules could “be improved” and that “subsequent rulemakings . . . may be appropriate to refine the Updated Form Further and strike the proper balance between the Updated Form’s benefits and burdens.” Now, the FTC appears to be engaging in such refinement.

Looking ahead

The immediate practical effect of this development is that the pre-February 2025 HSR rules will remain in effect for a considerable period. Even if the FTC meets its target of issuing a notice of proposed rulemaking by year-end, the federal rulemaking process requires additional steps before any new rule can take effect.

A proposed rule must be published in the Federal Register and subjected to a public comment period, which typically runs 60 days or longer for rules of this significance. After the comment period closes, the agency must review and respond to comments, draft a final rule, and publish it – a process that historically has taken months or, for complex rulemakings, well over a year.

The final rule must then provide a reasonable effective date, often 30 to 60 days after publication – though the FTC could set a longer implementation period to allow filers to adjust.

Given these procedural requirements, the pre-February 2025 HSR rules very likely will continue to govern premerger filings into 2027, depending on how the rulemaking proceeds.

For additional information, please contact the authors or other members of DLA Piper’s Antitrust and Competition team.