John Paulson is an American hedge fund manager and billionaire investor, best known for his successful bet against the U.S. housing market during the 2007-2008 financial crisis. He founded Paulson & Co. in 1994, building it into a prominent investment firm specializing in merger arbitrage, event-driven strategies, and credit opportunities. Paulson's career has been marked by high-profile trades and significant influence in the hedge fund industry.