This week, we’re rerunning some popular posts while we prepare for Friday’s live video webinar: 340B in 2026: Market Shifts, Policy Battles, and What They Mean for Stakeholders.

Click here to see the original post from March 2026.
By Adam J. Fein, Ph.D.

Three is still the magic number for pharmacy benefit managers (PBMs).

For 2025, 80% of all equivalent prescription claims were processed by three companies: the CVS Caremark business of CVS Health, the Express Scripts business of Cigna, and the Optum Rx business of UnitedHealth Group. Express Scripts continued to pull ahead of its peers, while CVS Caremark’s claim volume declined for the second year.

Independent PBMs continued to gain business from these larger PBMs, showing fragmentation at the margins. Many smaller PBMs still rely on their larger competitors for claims processing, network management, and rebate negotiation. So even if a plan sponsor chooses an alternative PBM, the Big Three can still win with behind-the scenes economics.

Below, we draw on DCI's new 2026 Economic Report on U.S. Pharmacies and Pharmacy Benefit Managers to break down the latest market share data for the largest companies.

The Big Three PBMs’ dominance persists, but they face growing regulatory and competitive constraints. The largest PBMs are restructuring their businesses in response to client demands, legislative changes, and legal pressures. The emerging Net Pricing Drug Channel will accelerate these shifts, forcing changes in how PBMs generate profits, structure contracts, and justify their role in the drug channel.
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