“People want to make sure they’re not paying for treatments or procedures their members or patients shouldn’t be getting,” Henry said.

Express Scripts said that the deal, which must be approved by regulators, is expected to close in the fourth quarter of 2017. EviCore will be run as a standalone business unit within Express Scripts, the company said.

Express Scripts shares have been under pressure recently amid renewed speculation that Amazon.com could move into pharmacy benefits, a development that could threaten Express Scripts and rivals including CVS Health Corp. and UnitedHealth Group Inc.’s OptumRx. Together, the three companies process about 70 percent of prescriptions in the U.S., according to Pembroke Consulting.

Amazon.com has never commented on whether it will enter the prescription-drug or drug-benefits market.

Meanwhile, Express Scripts is trying to prevent Anthem from severing ties when its current contract expires at the end of 2019. Anthem has accused Express Scripts of overcharging it by $3 billion a year and has said it expects to make a decision by year-end on what it will do. Express Scripts has denied overcharging Anthem.