1 BlueCross BlueShield of Tennessee, the Chattanooga-based health insurer that operates as a nonprofit affiliate of the BlueCross network, insured 1.6 million Tennesseans last year.
2 UnitedHealth Group, based in Minneapolis, insured 1 million Tennesseans last year and provided some type of health care coverage to more than 75 million subscribers nationwide last year.
3 Cigna Healthcare, the Philadelphia-based insurer that operates one of its service divisions in Chattanooga, insured 620,374 Tennesseans among its 60 million subscribers worldwide.
4 Humana, based in Louisville, Ky., insured 242,245 Tennesseans last year and has more than 17 million medical or specialty members nationwide.
5 Aetna, based in Hartford, Conn., insured 207,435 Tennesseans among more than 35 million members nationwide.
Source: HealthLeaders Interstudy, enrollments as of July 2010