PBM — Pharmacy Benefit Manager
A Pharmacy Benefit Manager (PBM) is the intermediary that administers prescription-drug benefits for health plans and employers — deciding which drugs a plan covers, negotiating rebates with drug manufacturers, and setting how much pharmacies are reimbursed. The three largest PBMs, each owned by one of the three largest U.S. health insurers, process roughly 80% of U.S. prescriptions.
What It Is
PBMs sit at the center of the prescription-drug supply chain, between four parties: the health plans that hire them, the drug manufacturers they negotiate with, the pharmacies they pay, and the patients who fill the prescriptions. From that position they perform three core functions: they build the formulary (the list of which drugs a plan covers and on what terms), they negotiate rebates from manufacturers in exchange for favorable formulary placement, and they set reimbursement — the amount pharmacies are paid for dispensing a drug.
Because the PBM controls the formulary, it also controls tools like prior authorization and step therapyStep Therapy“Fail first” — requiring a patient to try cheaper treatments before the insurer will approve the one the physician actually ordered. at the pharmacy counter — the same access-gating mechanisms that appear on the medical-benefit side.
The Big Three — and Who Owns Them
The three largest PBMs are each owned by one of the three largest health insurers — a textbook case of vertical integrationVertical IntegrationOne company owning multiple layers of the care-delivery chain — insurer, PBM, pharmacy, and physician group — so that every denial can also be a revenue event.:
In its 2024 interim staff report, the Federal Trade Commission found that the three largest PBMs processed about 80% of U.S. prescriptions, and the top six about 94% — and raised concerns that their vertical integration with insurers and pharmacies can disadvantage independent pharmacies and patients.
How the Money Moves
Several PBM revenue practices have drawn regulatory scrutiny. The FTC and others describe them factually as follows:
- Rebates: manufacturers pay PBMs rebates for favorable formulary placement, which can create an incentive to prefer drugs with higher list prices (and larger rebates) over lower-priced alternatives.
- Spread pricing: the PBM charges the health plan more for a drug than it reimburses the pharmacy, and keeps the difference.
- Steering: formulary and network design can direct patients toward the PBM's own affiliated pharmacies, including its mail-order and specialty pharmacies.
- Specialty markups: the FTC found the major PBMs marked up numerous specialty generic drugs dispensed at their affiliated pharmacies by thousands of percent over estimated acquisition cost.
Why It Matters for Reform
PBM reform is one of the few healthcare issues with sustained bipartisan attention. Because the three dominant PBMs are owned by the three dominant insurers, the PBM debate is inseparable from the broader vertical-integrationVertical IntegrationOne company owning multiple layers of the care-delivery chain — insurer, PBM, pharmacy, and physician group — so that every denial can also be a revenue event. debate that S.3822 (the Break Up Big Medicine Act) targets: the same parent company can own the insurer that approves the drug, the PBM that decides the formulary, and the pharmacy that fills it.
Proposed remedies range from delinking PBM compensation from drug prices and banning spread pricing, to transparency mandates, to structural separation of PBMs from insurers and pharmacies.
Related Terms
Sources: Federal Trade Commission, Pharmacy Benefit Managers: The Powerful Middlemen Inflating Drug Costs and Squeezing Main Street Pharmacies (interim staff report, July 2024) and its January 2025 follow-on report on specialty-generic markups. Market-share and ownership figures reflect 2023–2024.