Late Monday evening, health insurer Aetna confirmed a major pullback from Obamacare’s exchanges for 2017. The carrier, which this spring said it was looking to increase its Obamacare involvement, instead decided to participate in only four state marketplaces next year, down from 15 in 2016. Aetna will offer plans in a total of 242 counties next year — less than one-third its current 778. Coupled with earlier decisions by major insurers Humana and UnitedHealthGroup to reduce their exchange involvement, Aetna’s move has major political and policy implications

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