When Michael Neidorff took charge at Centene in 1996, it was a regional Medicaid insurer with $40 million in revenues. Today, it’s a managed care behemoth with about $20 billion in revenues over the past 12 months and 4.6 million members in 23 states. The transformation of U.S. healthcare created the opening—and Neidorff grabbed it. “He has read the market opportunities pretty accurately and positioned his company to take advantage of them,” says Thomas Carroll, an analyst with Stifel Nicolaus. Now one of the nation’s largest Medicaid contractors, Centene has skillfully expanded—with more than 25 acquisitions on Neidorff’s watch—into Medicare, prison healthcare, and the lucrative specialty pharmacy business. Centene’s prognosis is still healthy: The company is projecting a 16% revenue increase in 2016.