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. Gilead was founded in 1987 under the name Oligogen by Michael L. Riordan. The original name was a reference to oligonucleotides, small strands of DNA used to target genetic sequences. Gilead held its IPO in 1992, and successfully developed drugs like Tamiflu and Vistide that decade. In the 2000s, Gilead received approval for drugs including Viread and Hepsera, among others. It began evolving from a biotechnology company into a pharmaceutical company, acquiring several subsidiaries, though it still relied heavily on contracting to manufacture its drugs. The company continued its growth in the 2010s. However, it came under heavy scrutiny over its business practices, including extremely high pricing of drugs such as Sovaldi and Truvada in the United States relative to production cost and cost in the developing world. Wikipedia