Billionaire John Paulson’s hedge funds gained in April after successful wagers on energy, mergers and Greek banks. Paulson Partners gained 1.5 percent last month and 6.1 percent this year, said the people. The hedge fund manager, who made $15 billion in 2007 betting against U.S. mortgages, is rebounding from the firm’s second-worst year on record. SkyBridge Capital, which allocates about $13.1 billion to hedge funds, said this month that it’s favoring event-driven managers such as Paulson because they can make money in a bull market.