Lantheus Holdings Announces Merger Update; HSR Waiting Period Restarted

What Happened

• Lantheus Holdings, Inc. announced an update to the previously disclosed Agreement and Plan of Merger (entered Aug 3, 2026) with Curium US Holdings LLC (Parent) and Coco Merger Sub Inc. (Merger Sub). Under the agreement, Merger Sub will merge into Lantheus, leaving Lantheus as a wholly owned subsidiary of Parent upon closing.
• To give the Federal Trade Commission (FTC) additional review time, Parent — in consultation with Lantheus — voluntarily withdrew its pre‑merger Notification and Report Form under the Hart‑Scott‑Rodino (HSR) Act on Sept 17, 2026, and then refiled it on Sept 21, 2026. The refiling begins a new 30‑day HSR waiting period that currently expires Oct 21, 2026 at 11:59 p.m. ET, unless extended by an FTC request for more information.
• Lantheus and Parent say they continue to work with FTC staff and still expect to close the Merger in the first half of 2027, subject to regulatory approvals, stockholder approval of the Merger Agreement, and other customary closing conditions.

Key Details

• Merger Agreement date: August 3, 2026; acquiring party: Curium US Holdings LLC; merger vehicle: Coco Merger Sub Inc.
• HSR timeline: withdrawal on Sept 17, 2026; refiling on Sept 21, 2026; new statutory waiting period expires Oct 21, 2026 (may be extended if FTC requests additional info).
• Proxy: Lantheus filed the definitive proxy statement with the SEC on Sept 8, 2026; investors are urged to read that filing and related SEC filings (available at sec.gov and on Lantheus’ investor site).
• The filing reiterates forward‑looking risk factors, including regulatory approval, stockholder vote, milestone payments tied to contingent value rights (CVRs), and other customary closing risks.

Why It Matters

• Timeline and regulatory risk: The withdrawal and refiling effectively pauses and restarts the HSR clock, giving the FTC more time to review; this can delay closing and leaves the deal subject to additional antitrust scrutiny or information requests.
• Impact on investors: The Merger will make Lantheus a private, wholly owned subsidiary if completed; uncertainty around regulatory approvals, the required stockholder vote, and CVR milestone outcomes may affect shareholder value and timing of any cash/other consideration.
• Next steps to watch: whether the FTC extends the waiting period or issues a Second Request, the outcome of the stockholder vote, any further regulatory conditions, and updates in Lantheus’ proxy and SEC filings.