Why Are Centene and Molina the Exception To Most Big Health Plan Losses On the Obamacare Exchanges?

This paragraph in a recent AP story caught my eye:

Two companies that report exchange success so far, Molina Healthcare Inc. and Centene Corp., say they have focused on covering low-income customers in markets where they already have an established presence in Medicaid, the state-federal program that covers the poor. Molina sells coverage in nine states and is thinking about adding two for next