After Cigna Inc.’s acquisition of Express Scripts Holding Co. , Diplomat Pharmacy Inc. could be the next takeover target, Height Capital Markets analyst Andrea Harris said on Tuesday. Potential buyers could include online retailer Amazon , which has reportedly expressed an interest in health care, or health insurers Humana or Centene , according to Harris. Diplomat is the largest independent provider of expensive specialty drugs for such diseases as cancer, hepatitis C, autoimmune conditions and more. It also acquired two pharmacy-benefit managers — LDI Integrated Pharmacy Services and Pharmaceutical Technologies Inc. — last fall, which looked to be “a sign the firm was positioning itself as an attractive acquisition target by broadening its offering beyond specialty pharmacy,” Harris said. “The maneuver shifted DPLO from a specialty pharmacy to a middle market [pharmacy-benefit manager with a specialty drug focus, which represents an increasingly essential offering.” Pharmacy-benefit managers have been subject to increasing competitive and political pressure of late, as health insurers have moved drug price negotiation in-house and pharmacy-benefit managers have been accused of helping drive drug prices up. Diplomat shares were not active in Tuesday premarket trade. Company shares have surged 10.5% over the last three months, compared with a 4.5% rise in the S&P 500 .