Insurer stocks fall after Trump says 'we're going to knock out the middleman'

CVS Health's Caremark, Cigna's Express Scripts and UnitedHealth Group's Optum control the majority of the U.S. pharmacy benefit market, with their parent companies also operating health insurance and pharmacy businesses. Pharmacy benefit managers negotiate drug costs with pharmacies and drug manufacturers and help build drug coverage lists for health plans, mostly on behalf of employers and the government.