NBCUniversal Inc. August 23, 2019 9:28 am David Koch Dies at 79 David Koch, the billionaire conservative activist and philanthropist, has died at the age of 79. US & World Videos 1:49 Finalists in math competition hope their model helps ease housing crisis 14:31 @Issue extra: Seth Moulton on pro-Palestinian protests, TikTok and more 2:31 Celtics preparing for pivotal Game 3 against Heat in Miami 1:17 Patriots player visits Franciscan Children's Hospital 5:54 Pro-Palestinian protest taking over college campuses