With shares rising on M&A chatter, Arrowhead points to pipeline moves in 2020

Buoyed by news of this week's takeout of Medicines Co., Arrowhead is riding a wave of investor enthusiasm for RNAi therapeutics that has quintupled the company’s share price this year, and has boosted its valuation by 40% so far this week.

Shares of Arrowhead Pharmaceuticals Inc. (NASDAQ:ARWR) have gained $19.82 to $69.02 since Friday's close, adding about $1.9 billion in market cap to push its valuation above $6.6 billion. The company ended 2018 with its share price at $12.42...