Express Scripts is the biggest Pharmacy Benefit Manager, the drug-plan middleman owned by insurer Cigna's Evernorth arm.
It sits between insurers, drugmakers and pharmacies, managing prescription benefits for a huge share of the country.
It holds about 30-31% market share and 120M+ covered lives, grew in 2024 by taking the Centene contract from rival CVS Caremark, and runs the same all-in-one model: insurer plus benefit manager plus pharmacy plus care delivery under one roof.
It's the largest of a tiny group of middlemen who quietly control drug access and pricing for a large slice of America.