What is PBM vertical integration and why does it matter?

PBM vertical integration is the structural arrangement where the three largest US PBMs are each owned by or commonly owned with major health insurers and pharmacy chains. The arrangement gives the integrated entity simultaneous control over claim adjudication, formulary design, retail dispensing, specialty pharmacy, and (in some cases) plan administration and provider networks.

The three dominant integrations:

CVS Health. Owns CVS Caremark (PBM), CVS Pharmacy (retail), CVS Specialty (specialty pharmacy), Aetna (insurer), and Oak Street Health (primary care).

Cigna / Evernorth. Owns Express Scripts (PBM), Accredo (specialty pharmacy), Cigna (insurer), and various provider services.

UnitedHealth Group. Owns OptumRx (PBM), Optum specialty pharmacy, UnitedHealthcare (insurer), and a growing provider footprint through Optum Health.

Why it matters for plan sponsors:

Vertically integrated PBMs can steer prescriptions to their owned pharmacies, capturing additional margin at multiple points in the supply chain. Generic substitution that routes claims AWAY from the owned pharmacy reduces PBM margin in two places simultaneously — both the spread and the dispensing margin. This creates structural resistance to formulary changes that would benefit the plan, often appearing as process objections (P&T review delay, member-disruption modeling concerns) rather than direct refusal.

The FTC's 2024 report identified this dynamic as a primary driver of inflated commercial drug costs. Plans negotiating with integrated PBMs should specifically address pharmacy network exclusivity and steering practices in contract language.