Government officials have said that the exchanges will keep insurers’ prices down by making them compete with each other. Prices on the exchanges have been lower than government forecasts, partially a sign of “healthy competition,” Cohen says, and are generally lower in more competitive markets. So far, though, the marketplaces seem to be having another effect on major insurance companies, too: Scaring them away.

Large insurers like Cigna and UnitedHealth have abstained from many states’ exchanges this year; Aetna has backed out of seven exchanges it originally applied to, instead “focusing on the markets where we can be most competitive and deliver the greatest value to our customers,” a spokesperson says. In Mississippi, 36 counties would not have had any plan options if Humana had not joined at the 11th hour, Melville says. “There were concerns there would be coverage deserts, there would be places that you wouldn’t be able to get a policy.” This hasn’t happened, but some states have so few carriers offering plans in the marketplaces that the lack of competition has kept rates high.

West Virginia and New Hampshire, for example, currently have only one carrier for their entire states, respectively. Wyoming only has two, after most of the state’s insurers skipped the exchange, and has the highest rates in the country. Analysts, however, say that there is likely to be more competition in future years: Insurers will wait and see how 2014 plays out and re-evaluate their strategies. Aetna, for one, says it is “taking a measured, multiyear approach to exchanges.”