Healthways Inc.'s contract with its biggest customer, Cigna, doesn't expire for another 18 months, but there's one stock analyst out there suggesting the Franklin-based company runs the risk of losing that big fish. The comments by JMP Securities analyst Constantine Davides caused shares of the Franklin-based disease management firm to drop 13 percent a couple of weeks ago from its recent high of $17.51 per share. On Wednesday, Healthways was trading in the neighborhood of $13.85 a share on Nasdaq, up slightly during a bumpy day on Wall Street. "Healthcare is changing rapidly and it's a different world today than the last time they renewed the contract," said Davides, a Boston-based analyst who says the Cigna work accounted for roughly 19% of Healthways revenues last year. So, it would be a lot of dough to lose. He downgraded Healthways to "market underperform" and set a target price of $13 per share—meaning that's where he thinks the stock is headed. In support of his thesis, Davides cited recent moves by other big health plans to bring once-outsourced services in-house. They include UnitedHealth Group's move to not renew a pharmacy benefits contract with Medco Health Solutions, and Humana bringing more of its disease management services in-house.