Amgen will acquire Horizon Therapeutics, a biopharmaceutical company that focuses on treatments for rare, autoimmune diseases, for about $26.4 billion.
Each Horizon shareholder will receive $116.50 per share for each share they own. The deal has an enterprise value of about $28.3 billion, Amgen said.
Shares of Horizon jumped nearly 14% before the opening bell Monday.
U.S.-traded shares of Horizon soared about 30%, past $100, after the company confirmed late last month that it had begun “highly preliminary discussions” about an acquisition with Amgen, the French drugmaker Sanofi, and Johnson & Johnson’s Janssen division.
Amgen confirmed discussions were taking place in early this month and said at the time that any offer it made for Horizon likely would be in cash, but also that there was no guarantee an offer would be made.