Cigna primarily provides pharmacy benefit management and health insurance services. Its PBM and specialty pharmacy services, which were greatly expanded by its 2018 merger with Express Scripts, are mostly sold to health insurance plans and employers. Its largest PBM contract is the Department of Defense, and it recently won a deal with top-tier insurer Centene. In health insurance and other benefits, Cigna mostly serves employers through self-funding arrangements, and the company operates mostly in the US with 18 million US medical members covered as of December 2023.