China’s summer market selloff wasn’t a total rout if you were one of the country’s top-performing hedge funds that gained an average 70 percent as almost 1,300 other funds were wiped out. The country’s top 10 performers, run by Ze Quan Investment, Sunrise Investment, Zexi Investment and Yingyang Asset Management, found gains in the June-August period by heeding a famous maxim: Markets are ruled by fear and greed. “I was scared,”...