Trendwatch Chartbook for 2020, by American Hospital Association (AHA). See Table 1.13 for 2019 operating margins of insurance company giants Aetna, Anthem, United HealthCare, Cigna and Humana. Supplementary appendixes only are available. Most tables contain 2018 or more recent data. 48 pages, published January 2020. The full Trendwatch chartbooks are available to members only.