They got around that rule by buying out pharmacy benefit managers (PBMs), hospitals, doctor's offices, and pharmacies. While the health insurance side of UnitedHealthCare is capped at 20% or 15% overhead, they can realize their earnings by marking up the price of drugs through their pharmacy subsidiary OptumRx. They steer customers toward OptumRx by structuring their health insurance to favor that pharmacy.

CVS bought Aetna [health insurance]. CVS also owns CVS Caremark a PBM. If your employer picked Aetna as your health insurance you must fill your meds at a CVS.