12. AbbVie

Coming off what AbbVie's board dubbed an “exceptional year,” 2016 may sting. Experts wonder if the biopharma giant can keep its momentum, particularly as Humira inches closer to the patent gangplank. Aiming to parlay its biologic expertise — the proof's in the Humira pudding — AbbVie forked over $595 million for sole marketing rights to Boehringer Ingelheim's late-stage psoriasis drug BI 655066. In a move some analysts see as a high-stakes gamble, AbbVie shelled out $21 billion last year for Pharmacyclics and its cancer drug Imbruvica, jointly commercialized with J&J. CEO Rick Gonzalez laid out a three-pronged plan to siphon $12 billion in sales out of Imbruvica to recoup acquisition costs. Imbruvica broke into a larger market, courtesy of an FDA nod for first-line treatment of CLL. The pressure's on Viekira Pak to ramp up its performance, even as it has already brought in $1.6 billion in sales. That's a tall order in light of an FDA safety warning and stiff competition from Gilead and new category entrant Merck.