Many of the insurers chose to operate in those states where they already serve the individual market. Some of those customers could now be eligible for subsidized coverage through exchange plans.
"All of the individual members at Health Net and WellPoint can still purchase an exchange product from their current individual carrier next year," wrote Citi analyst Carl McDonald in a note to clients.
WellPoint, through its Blue Cross subsidiaries, has among the most aggressive exchange strategy. It offers plans on 14 state exchanges, with more than half on the federal exchange.
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By contrast, UnitedHealth Group is offering plans on just five exchanges, all of them state run, including New York and Maryland. That means no exposure to federal exchange glitches, but also the potential for market share losses in the states where it still participates in the individual market.
"United will lose the largest number of individual lives in states like Florida, Texas, Arizona, and Missouri," wrote McDonald. "Not offering a subsidy-eligible exchange product clearly puts United more at risk of membership losses."
Aetna has taken the most aggressive exchange strategy of the major carriers, offering plans on the District of Columbia's exchange and in 16 states, including Texas, Ohio and Illinois, that are on the federal exchange after opting out of building their own online marketplaces.
"I'm surprised to see how aggressive they were," said Wedbush analyst Sarah James.
Beyond the sheer number of states, James was surprised by Aetna's low-price plan offerings on those exchanges. The insurer is offering low-premium PPO, or preferred provider organization, plans, while many of its rivals have opted for more restrictive health maintenance organization plans.
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"People are going to choose the lowest price option," she said, "but being that low-priced provider on a product where it's harder to control costs does create some increased margin risk."
A lot of the risk will depend on who enrolls. Analysts suspect those signing up now are older and more in need of services. Younger, healthier enrollees are more likely to wait.
The Obama administration has not yet provided enrollment numbers from the federal exchanges. While some states have begun to report enrollment data, none has provided details about the demographics. Ignagni said it's early yet.
"In a couple weeks, we'll have a very real sense of what the numbers look like, and who's enrolling," she said.