AON vs CI Comparison

Aon is a leading global provider of insurance and reinsurance brokerage and human resources solutions. Its operations are tilted toward its brokerage operations. Headquartered in London, Aon has about 50,000 employees and operations in over 120 countries.

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 with the Department of Defense (current contract through 2029), and it recently won a multiyear deal with top-tier insurer Centene. In health insurance and other benefits, Cigna primarily serves employers through self-funding arrangements, and the company operates mostly in the US with 17 million US and 2 million international medical members covered as of December 2024.