Cardinal Health is primarily a pharmaceutical distributor, buying branded drugs, generics, specialty pharmaceuticals, and over-the-counter products from manufacturers and distributing them to retail pharmacies, hospitals, health systems, and other healthcare providers across the U.S. Drug distribution generates over 90% of revenue and operates on very thin margins, meaning small changes in volume, mix, or fee structures have an outsized impact on earnings. Cardinal Health earns fees from branded manufacturers tied to wholesale acquisition cost, and earns discounts and rebates on generics sourced through Red Oak Sourcing, a 50/50 joint venture with CVS Health. CVS Health is Cardinal Health's largest single customer at 30% of revenue. Beyond core distribution, Cardinal Health operates a Global Medical Products and Distribution (GMPD) segment that manufactures and sources Cardinal-branded surgical and medical-surgical supplies and distributes national brand products to hospitals and labs. Cardinal Health has invested heavily in specialty services, building a physician practice management platform in oncology (Navista) and gastroenterology and urology (GI Alliance), which earn higher-margin management fees, ancillary service revenue, and drug distribution volumes through affiliated practices. The company also operates nuclear pharmacies that prepare and deliver radiopharmaceuticals, a fast-growing theranostics business, a direct-to-patient medical supplies business (at-Home Solutions), and a logistics management platform (OptiFreight). Cardinal Health's long-term strategy centers on expanding these higher-margin specialty and adjacent businesses while defending its core distribution franchise.