Shares of generic drugmaker Actavis have gone on a huge run lately, which has caught the attention of would-be acquirers. But instead of getting gobbled up, Actavis went on the offense and will buy a spec pharma for $8.5 billion.

In this video, health-care analyst David Williamson discusses the merits of two competing deals for Actavis, one from generic drug company Mylan and another from serial acquirer Valeant. He also talks about why Actavis' purchase of Warner Chilcott worked out for the best for all parties involved.