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ARTICLE · 26 FEBRUARY 2026

Overhauled HSR Rules To Remain In Effect For Now

Mayer Brown
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After an eventful week, bipartisan changes to Hart-Scott-Rodino Act ("HSR Act") premerger notification rules finalized in October 2024 will remain in effect until the Fifth Circuit issues a decision on a stay pending appeal.

United StatesAntitrust/Competition Law
William Stallings
William Stallings
Rachel J. Lamorte
Rachel J. Lamorte
Oral Pottinger
Oral Pottinger
Scott Perlman
Scott Perlman
Ora Nwabueze
Ora Nwabueze
Lauren E. Knudson
Lauren E. Knudson
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After an eventful week, bipartisan changes to Hart-Scott-Rodino Act ("HSR Act") premerger notification rules finalized in October 2024 will remain in effect until the Fifth Circuit issues a decision on a stay pending appeal. The rules have been in effect since February 2025. Transacting parties should plan to continue to use the new rules in the short term, but the applicability of the rules going forward is still to be determined by the Fifth Circuit. A summary of the rule changes and state of play is below.

2024 Changes to the HSR Rules

After much buildup, in October of 2024, the FTC voted unanimously to issue a final rule enacting changes to the HSR premerger notification rules. This represented the first major change to HSR reporting requirements since the HSR Act was passed in 1976.

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This Mayer Brown article provides information and comments on legal issues and developments of interest. The foregoing is not a comprehensive treatment of the subject matter covered and is not intended to provide legal advice. Readers should seek specific legal advice before taking any action with respect to the matters discussed herein.

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