UNH vs MRK Comparison

UnitedHealth Group is one of the largest private health insurers and provides medical benefits to about 51 million members globally, including 1 million outside the US as of December 2025. As a leader in employer-sponsored, self-directed, and government-backed insurance plans, UnitedHealth has obtained massive scale in medical insurance. Along with its insurance assets, UnitedHealth's Optum franchises help create a healthcare services colossus that spans everything from pharmaceutical benefits to providing outpatient care and analytics to affiliates and third parties.

Merck makes pharmaceutical products to treat several conditions in a number of therapeutic areas, including cardiometabolic disease, cancer, and infections. Within cancer, the firm's immuno-oncology platform, led by Keytruda, is a major contributor to overall sales. The company also has a substantial vaccine business aimed at preventing pediatric diseases, as well as Gardasil for human papillomavirus. Additionally, Merck sells animal health-related drugs. From a geographical perspective, 47% of the company's sales are generated from US human health (pharmaceuticals and vaccines).