Form 8-K Filing Regarding Merger Agreement

On September 17, 2026, Lantheus Holdings, Inc. announced that its merger partner, Parent, voluntarily withdrew its pre-merger Notification and Report Form filed pursuant to the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (HSR Act). This action was taken in consultation with Lantheus to allow the Federal Trade Commission (FTC) additional time for review. Parent resubmitted the form on September 21, 2026, initiating a new 30-day waiting period under the HSR Act, set to expire on October 21, 2026. This withdrawal and refiling is a standard procedure to facilitate antitrust review. Lantheus and Parent continue to cooperate with the FTC and anticipate the merger