After spending three decades focusing on things like economic trends, currency moves, politics and policy, Spindel has been confounded by markets shaped by low volatility, algorithms and more. He finally gave up and closed his nine-year-old hedge fund. “I felt the intensity of following markets at a time of increasing political and economic confusion very hard,” said Spindel, founder of Potomac River Capital in Washington. “My entire career had centered on an understanding of monetary politics and I had trouble getting my head around it all. It was exhausting.” These are troubled -- and troubling -- times for macro managers,...