What Are PBM Rebate Walls?
How pharmacy benefit managers affect biologic drug pricing and patient access
Key Points
- Pharmacy Benefit Managers (PBMs) are intermediaries between insurers, pharmacies, and drug manufacturers
- PBMs negotiate rebates from manufacturers in exchange for favorable formulary placement
- A rebate wall occurs when brand manufacturers offer such large rebates that lower-list-price biosimilars cannot compete for formulary access
- Rebate walls have slowed biosimilar adoption for some medications despite lower list prices
- Healthcare policy debates around PBM reform are ongoing in Congress
What Is a Pharmacy Benefit Manager (PBM)?
A Pharmacy Benefit Manager is a third-party company that manages prescription drug benefits on behalf of health insurers, employers, and government programs. The three largest PBMs — CVS Caremark, Express Scripts (Cigna), and OptumRx (UnitedHealth) — collectively manage pharmacy benefits for hundreds of millions of Americans.
PBMs develop formularies (lists of covered drugs), negotiate prices with pharmacies, process pharmacy claims, and negotiate rebates with drug manufacturers. Rebates are payments manufacturers make to PBMs — and in theory to health plans — in exchange for preferred formulary placement.
How Rebate Walls Work
Here is a simplified example: A brand biologic has a list price of $60,000/year and offers a 40% rebate to PBMs — effectively a $24,000 payment per patient per year in exchange for preferred formulary status. A biosimilar with a list price of $45,000/year would need to offer equivalent or higher rebates to compete for the same formulary position. Since the biosimilar's list price is already lower, it has less margin to offer in rebates — creating a structural disadvantage called a rebate wall.
Critics argue rebate walls protect high-list-price brand drugs from biosimilar competition, maintaining high gross list prices while reducing net prices through rebates — a system that can harm uninsured or cost-sharing patients who pay based on list price rather than net price.
Impact on Biologic Patients
💊 Formulary Placement
Biosimilars with lower list prices may be placed on higher formulary tiers than brand biologics if the brand manufacturer's rebates secure preferred positioning. This can paradoxically make the lower-list-price biosimilar more expensive for the patient.
💰 Copay Impact
Patients pay copays based on formulary tier, not list price. A biosimilar on Tier 4 may cost more out-of-pocket than a brand biologic on Tier 2, even if the biosimilar has a lower list price.
🚫 Access Barriers
If a patient's insurance covers only the biosimilar and not the reference biologic (or vice versa), they may face prior authorization challenges if their prescriber prefers the other option.
✅ How to Protect Yourself
BiologicHealthPlus verifies your specific formulary placement and cost-sharing for both the reference biologic and all biosimilars — then identifies the lowest-cost option for your plan.
💬 BiologicHealthPlus Finds Your Lowest Cost Regardless of PBM Policies
We navigate the complex formulary landscape on your behalf — comparing all options on your specific plan to minimize your out-of-pocket cost.
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Content developed with reference to leading health organizations, peer-reviewed research, and FDA prescribing information.
Medical Disclaimer: Educational content reviewed by the BiologicHealthPlus Clinical Team. Consult your healthcare provider for personalized advice. Last reviewed: August 2026.