Pete Peterson, who co-founded Blackstone Group in 1985 with Stephen Schwarzman, has passed away, according to the Associated Press. Peterson, 91, died of natural causes, the story said. Peterson was head of two major companies before he helped launch Blackstone. In the 1960s, he was CEO of Bell and Howell, which made movie cameras at the time. Peterson took over as head of Lehman Brothers in 1973, the AP said. Blackstone’s IPO in 2007 made Peterson a billionaire.