In a wide-ranging interview, the Blackstone founder and CEO offers his advice to young entrepreneurs and discusses his view of tense U.S.-China trade talks. Stephen A. Schwarzman is the ultimate master of the universe. From running Blackstone, the world’s largest private equity firm with almost $500 billion in total assets under management, to acting as President Trump’s “China whisperer” during the last two years of tense trade talks, the 72-year-old financier wields plenty of power.