Gilead Sciences Inc. is an American biopharmaceutical firm that was founded in 1987 under the name Oligogen by Michael L. Riordan. The company specializes in the research, development and sale of medicines in underdeveloped research areas. To this end, the company engages its research in such areas as the human immunodeficiency virus, acquired immunodeficiency syndrome, liver diseases, hematology, oncology, and inflammation and respiratory diseases. It offers antiviral products under many brand names, including Harvoni, Genvoya, Epclusa, Truvada, Atripla, Descovy, Sovaldi and more. The company is headquartered in Foster, California, and its stock is measured on the NASDAQ Biotechnology Index and the S&P 500 Index.