These are the stocks posting the largest moves in midday trading. : Horizon Therapeutics – Shares of the drugmaker jumped 15% after the company announced it has agreed to be acquired by Amgen in a deal valued at approximately $26.4 billion, or $116.50 per share, in cash. The deal will give Amgen a chance to build its portfolio of rare-disease treatments. Amgen shares fell more than 1%. Weber – Shares of the grill manufacturer jumped 23% after the company announced a deal to be taken private by BDT Capital Partners. BDT will purchase Weber for $8.05 per share, according to the announcement.