The good news: Platinum says it’s making money, just as it has in each of the past 13 years. Since it was founded in 2003, its main fund has gained an average of about 17 percent annually, according to an investor presentation. That’s on a par with the world’s best-performing hedge funds, such as Bill Ackman’s Pershing Square Capital Management and Israel Englander’s Millennium Management. Platinum’s specialty is investing in companies...