David Koch during an interview in Cambridge, Mass., on March 4, 2011. Koch, who joined his brother, Charles Koch, in business and political ventures that grew into the nation's second-largest private company and a powerful right-wing libertarian movement that helped reshape American politics, has died, his brother Charles announced on Friday, Aug. 23, 2019. He was 79.  (Gretchen Ertl/The New York Times)