Sanofi and Boehringer Ingelheim agreed to a $25 billion dollar trade of big business units this week, the conclusion of a deal that first surfaced in December. Asset swaps, while complicated, could be an increasingly popular maneuver among pharmaceutical companies, Bloomberg M&A reporter Ed Hammond tells host and colleague Alex Sherman. That's partially because the biggest takeovers in the industry can't seem to get done. Hammond explains why they've failed and what pharma deals might actually get done in the second half of 2016.