"Health plan mergers over the last decade

... have mostly not raised antitrust concerns because they have usually involved partners with one of them having very little share in the market. Today's mergers [like Aetna's proposed acquisition of Humana] are more complex. I think in the past, mergers have happened one at a time. This is almost like someone shot a starter pistol and everyone merged at the same time."

— Paul Ginsburg, Ph.D., director of public policy for the Schaeffer Center for Health Policy and Economics at the University of Southern California, told AIS's Health Plan Week.