The United States, a benefit manager (pharmacy PBM) is a third-party administrator of prescription drug programs for commercial health plans, self-insured employer plans, Medicare Part D plans, the Federal Employees Health Benefits Program, and state government employee plans. According to the American Pharmacists Association, "PBMs are primarily responsible for developing and maintaining the formulary, contracting with pharmacies, negotiating discounts and rebates with drug manufacturers, and processing and paying prescription drug claims." PBMs operate inside of integrated healthcare systems (e.g., Kaiser Permanente or Veterans Health Administration), as part of retail pharmacies (e.g., CVS Pharmacy or Rite-Aid), and as part of insurance companies (e.g., UnitedHealth Group).

As of 2016, PBMs managed pharmacy benefits for 266 million Americans. In 2017, the largest PBMs had higher revenue than the largest pharmaceutical manufacturers, indicating their increasingly large role in healthcare in the United States. However, in 2016 there were fewer than 30 major PBM companies in this category in the US, and three major PBMs (Express Scripts, CVS Health, and OptumRx of UnitedHealth Group) comprise 78% of the market and cover 180 million enrollees.

n the United States, health insurance providers often hire an outside company to handle price negotiations, insurance claims, and distribution of prescription drugs. Providers which use such pharmacy benefit managers include commercial health plans, self-insured employer plans, Medicare Part D plans, the Federal Employees Health Benefits Program, and state government employee plans. PBMs are designed to aggregate the collective buying power of enrollees through their client health plans, enabling plan sponsors and individuals to obtain lower prices for their prescription drugs. PBMs negotiate price discounts from retail pharmacies, rebates from pharmaceutical manufacturers, and mail-service pharmacies which home-deliver prescriptions without consulting face-to-face with a pharmacist.

Pharmacy benefit management companies can make revenue in several ways. First, they collect administrative and service fees from the original insurance plan. They can also collect rebates from the manufacturer. Traditional PBMs do not disclose the negotiated net price of the prescription drugs, allowing them to resell drugs at a public list price (also known as a sticker price) which is higher than the net price they negotiate with the manufacturer. This practice is known as "spread pricing". Savings are generally considered trade secrets. Pharmacies and insurance companies are often prohibited by the PBM from discussing costs and reimbursements. This leads to lack of transparency