5. Pfizer

Pfizer's dream to shave the top off a rising U.S. tax bill — and level the playing field with overseas competitors — was dashed following the U.S. government's bold move to discourage further inversion deals. News of Pfizer's plans for a massive merger with Dublin-based Allergan first splashed across headlines late last year, triggering fierce blowback in some camps. The new regulations, spearheaded by POTUS, forced Pfizer's board to vote the deal dead in the water and hand over $150 million to cover Allergan's transaction expenses. On the product front, Celebrex is the pharma giant's latest blockbuster to fall victim to patent expiration; the company awaits a similar fate for Lyrica and Chantix. Following years of slashing its R&D budget, Pfizer needs a few pearls in its pipeline to step up to offset these losses. The Lipitor-famed company coughed up $15 billion for Hospira to pad its generics business with an arsenal of biosimilar candidates. Cancer continues to garner Pfizer's attention, with a focus on approved breast-cancer treatment Ibrance's utility in other forms of cancer and Xalkori's label expansion to treat lung-cancer patients with gene alteration. And there's always the firm's five biosimilars in development for conditions including arthritis and Crohn's disease.