 Amgen Inc. AMGN, -2.42 said Monday it has agreed to acquire Horizon Therapeutics Plc HZNP, 0.39 in an all-cash deal valued at 27.8 billion, confirming earlier reports and a deal that was first mooted in November. Under the terms of the deal, Amgen will pay 116,50 per each Horizon share owned, equal to a 47.9 premium over the stocks closing price on Nov. 29, the day before the deal was first announced. 