Amgen Inc on Monday agreed to buy Horizon Therapeutics Plc in a deal valued at $27.8 billion (£22.67bn), fortifying its rare diseases portfolio in the biggest
buyout in the sector this year.
The company will pay $116.50 in cash, a premium of nearly 20 per cent to the stock's last close, for each Horizon share.
Horizon shares closed up 15 per cent on Monday at $112.36. They had climbed 23.5 per cent through Friday since the company disclosed in late November it was in
preliminary talks with Amgen, Sanofi and Johnson & Johnson for potential offers. Amgen shares dipped less than 1 per cent to close at $276.78.
Sanofi said Sunday it ended discussions with Horizon after concluding the transaction prices "do not meet our value criteria."
J&J also said in early December that it had dropped its pursuit of the deal.