Shares of Idenix Pharmaceuticals Inc. (NASDAQ:IDIX) more than tripled last week after Merck & Co. Inc. (NYSE:MRK) said it will acquire Idenix for $24.50 per share in cash, or about $3.9B. The proposed takeout pushed the biotech's shares over $20 for the first time since 2006.

Idenix shares have largely traded below $10 for the past seven years, with the exception of a short-lived bump in early 2012 when Bristol-Myers Squibb Co. (NYSE:BMY) acquired another HCV play, Inhibitex Inc., for $2.5B. Over the years, Idenix has persevered through a number of setbacks, including the discontinuation of HCV compounds IDX320, IDX184 and IDX19368.