Some of the Affordable Care Act’s insurance marketplaces are in turmoil as the fourth open enrollment season approaches this fall, but what’s ahead for consumers very much depends on where they live.

Competition on these exchanges will be diminished next year when three of the nation’s largest health insurers — Aetna, UnitedHealthcare and Humana — will sell individual plans in many fewer markets. So too will several Blue Cross and Blue Shield plans in various states. That’s on top of the 16 nonprofit co-ops that have closed since January 2015.

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