Analysis: Three PBMs account for 80% of U.S. market share

Three pharmacy benefit managers (PBMs), Express Scripts, CVS Caremark, and Optum Rx, handled approximately 80% of all prescription claims in the United States in 2025, according to a new analysis from the Drug Channels Institute.

The Drug Channels Institute released its annual PBM market share analysis on March 30 as part of its 2026 Economic Report on U.S. Pharmacies and Pharmacy Benefit Managers. The data measure total equivalent prescription claims managed across the industry for the calendar year 2025.

PBMs operate as intermediaries between drug manufacturers, health insurers, and pharmacies. They process prescription claims and negotiate drug rebates on behalf of plan sponsors. The three largest PBMs—Express Scripts, CVS Caremark, and Optum Rx—are subsidiaries of Cigna, CVS Health, and UnitedHealth Group respectively. Each is vertically integrated with health insurance and pharmacy dispensing operations.

The business models of PBMs have come under scrutiny for practices such as spread pricing and rebate retention. According to the Government Accountability Office (GAO), health plans and other stakeholders have raised concerns about PBMs retaining a share of manufacturer rebates while paying pharmacies less than what they charge plans. Between 2017 and 2023, all 50 states enacted at least one law related to PBM practices.

In its July 2024 interim report, the Federal Trade Commission (FTC) said that vertically integrated PBMs can direct patients towards PBM-owned or affiliated pharmacies, particularly those using high-cost specialty drugs. The report explained how specialty drug designations, network rules, and exclusive pharmacy arrangements could channel prescriptions to affiliated dispensing channels. This increases PBMs' control over reimbursement and fulfillment processes.

The FTC's second interim report on PBMs released in January 2025 found that the "Big 3" PBMs significantly marked up numerous specialty generic drugs dispensed through their affiliated pharmacies by hundreds or thousands of percent above estimated acquisition costs. The agency reported that these markups generated more than $7.3 billion in excess revenue over six years on drugs used to treat cancer, HIV, and other serious conditions.

An Ohio state audit revealed that pharmacy benefit managers charged Medicaid a spread of more than 31% on generic drugs within a year-long period. This resulted in approximately $208 million collected above what was paid to pharmacies for dispensing these prescriptions. The audit provided a clear state-level example of how PBM spread pricing can inflate public drug costs while obscuring true reimbursement flows.

Adam J. Fein is president of the Drug Channels Institute, an HMP Global company. Fein holds a doctoral degree from the Wharton School of Business at the University of Pennsylvania and has published the Economic Report on U.S. Pharmacies and Pharmacy Benefit Managers annually since its inception.

Below is a table showing market shares among major PBMs:

2025 U.S. PBM Market Shares