The Minnesota health plan offered some of the lowest premiums in the country and captured 60 percent of the state's roughly 55,000 new Obamacare enrollees. But those premiums were too low, it turns out, to cover the medical care and other expenses of all those new customers. In the fall, PreferredOne steeply hiked rates for 2015 and dropped out of Minnesota's Affordable Care Act marketplace entirely, saying it was “not sustainable" to continue. - Business Week
They didn't charge enough.
See a pattern here?