Gilead Sciences is a biopharmaceutical company focused on HIV, viral hepatitis, and cancer. HIV is by far its largest business, representing roughly 72% of product sales, dominated by Biktarvy — a once-daily single-tablet HIV treatment that holds over 52% U.S. market share. Gilead also sells Descovy for daily oral HIV prevention (PrEP), and in mid-2025 launched Yeztugo (lenacapavir), a twice-yearly injectable PrEP that management views as a long-term blockbuster. Lenacapavir is Gilead's core pipeline platform, with multiple treatment and prevention combinations in development targeting launches through 2033. Beyond HIV, Gilead has a liver disease business built on hepatitis B and C products as well as Livdelzi, a recently launched therapy for primary biliary cholangitis that has quickly become the U.S. market share leader in second-line PBC. Gilead's oncology business centers on Trodelvy, an antibody-drug conjugate that is the standard of care in second-line metastatic triple-negative breast cancer, and Kite, a CAR-T cell therapy franchise targeting blood cancers. Gilead sells primarily through large drug wholesalers and specialty pharmacies in the U.S., with a direct sales force targeting physicians, hospitals, and clinics. The business model is built on branded specialty drug pricing, with product gross margins around 86%. Patent protection on Biktarvy runs through 2036, providing a long runway before generic competition. Gilead reinvests heavily in R&D and pursues bolt-on M&A to seed its pipeline, while returning the majority of free cash flow to shareholders via dividends and buybacks.