http://blogs.wsj.com/moneybeat/2014/01/31/reaching-the-top-ranks-of-blackstone-without-an-m-b-a/ By Mike Spector Real-estate guru Jonathan Gray heads Blackstone’s largest business, chairs the board of Hilton Worldwide Holdings Inc., just became a billionaire on paper and is in line to one day run the world’s largest private-equity firm. But he’s also notable for something he doesn’t have: an M.B.A. The 43-year-old Gray, who heads […]