Gilead Sciences, Inc. is an American biopharmaceutical company headquartered in Foster City, California that focuses on researching and developing antiviral drugs used in the treatment of HIV/AIDS, hepatitis B, hepatitis C, influenza, and COVID-19, including ledipasvir/sofosbuvir and sofosbuvir. Gilead is a member of the NASDAQ Biotechnology Index and the S&P 500.

Foster City is a master-planned city located in San Mateo County, California, United States. Foster City is sometimes considered to be part of Silicon Valley for its local industry and its proximity to Silicon Valley cities. There are many notable companies headquartered in Foster City like Gilead Sciences, Zoox, Sledgehammer Games, and Replit. Visa used to be headquartered in Foster City.