http://www.healthcaredive.com/news/whats-driving-the-big-health-insurance-mergers/402945/

As with the recent flurry of hospital mergers and acquisitions, the biggest driving force for the current insurance industry mergers is likely the Affordable Care Act (ACA). The New York Times says that although the ACA is bringing insurers more revenue by way of additional customers, greater pricing transparency and government funding cuts have also put more pressure on their profit margins.