Hedge fund billionaire Leon Cooperman told CNBC on Wednesday that the stock market could tumble as much as 25% if either Elizabeth Warren or Bernie Sanders wins the 2020 presidential election. The founder of Omega Advisors cited proposals from both candidates designed to tax wealthy individuals and billionaires. "You don't make poor people rich by making rich people poor," Cooperman said. Visit the Business Insider's homepage for more stories. Billionaire hedge fund manager Leon Cooperman is worried a presidential-election victory for either Elizabeth Warren or rival Bernie Sanders could send the stock market tumbling into a full-fledged bear market.