Medicare Part D: Payments and Contracts Between Pharmacies and Plan Sponsors That Are Vertically Integrated [Reissued with revisions on Oct. 6, 2026]

What GAO Found The insurance plan sponsors that provide Medicare Part D drug coverage have increasingly become vertically integrated—that is, under common ownership—with pharmacy benefit managers and pharmacies. GAO found that, for four large Part D plan sponsors, the pharmacies they owned accounted for about 28 percent of the Part D drugs they provided to their enrollees (drug utilization) and about 24 percent of the total payments to pharmacies in 2023 (see figure). Payments included both reimbursement from plan sponsors and cost sharing paid by or on behalf of beneficiaries.