Pfizer and Merck have done a good job beating Wall Street's per-share expectations in the face of real headwinds. Pfizer has gone through a dramatic reorganization to fight this challenge, while Merck is standing pat with its more diverse business model.

In this video, health-care analyst David Williamson discusses both companies second-quarter results in greater detail, how their different approaches are working out, and what key drugs in their respective pipelines investors should focus on.