David Hamilton Koch (/koʊk/; May 3, 1940 – August 23, 2019) was an American businessman, philanthropist, political activist, and chemical engineer. He joined the family business Koch Industries, the second-largest privately held company in the United States, in 1970. He became president of the subsidiary Koch Engineering in 1979, and he became a co-owner of Koch Industries, with elder brother Charles, in 1983. He served as an executive vice president until his retirement in 2018. Upon retirement in June 2018 due to health issues, Koch received the title of director emeritus.