Gilead Sciences (GILD)

HIV remains central to Gilead’s business, supported by single-tablet regimens and long-running expertise in antiretroviral drug development. In hepatitis C, the company became a major force through the acquisition of Pharmasset, which gave it rights to sofosbuvir, marketed as Sovaldi and used in several combination regimens. Those products helped transform hepatitis C treatment by enabling high cure rates with shorter oral therapy courses, although the market has matured as more patients have been treated.

Beyond antivirals, Gilead has expanded meaningfully into oncology and inflammatory disease. Its acquisition of Kite Pharma brought cell therapies including Yescarta and Tecartus, which are CAR-T treatments used in certain blood cancers. The purchase of Immunomedics added Trodelvy, an antibody-drug conjugate used in areas including breast and bladder cancer. These assets support Gilead’s strategy of building a broader specialty-medicine business alongside its established infectious disease franchise.

The company operates in a research-intensive and highly regulated industry where revenue depends on clinical trial success, patent protection, pricing, reimbursement, and competition from rival therapies and generics. Gilead’s distinguishing feature is its deep antiviral legacy combined with an increasingly diversified pipeline in oncology and immune-mediated conditions.