Washington State First To Enact Broad Premerger Notification Law

Introduction

The state of Washington became the first to enact a broad premerger notification law covering transactions across all industries. The law, S.B. 5122, was enacted on April 4, 2025, and goes into effect July 27, 2025. S.B. 5122,¹ modeled after the Uniform Antitrust Premerger Notification Act, which was drafted and approved by the Uniform Law Commission (ULC) in July 2024, will require covered merging parties to provide copies of their Hart-Scott-Rodino (HSR) merger filings to the Washington State Office of the Attorney General. Multiple other states, including New York and California, are considering adopting their own premerger notification laws.²

Provisions of Washington's Act