Most Wall Street traders early this year predicted oil prices would rebound through 2015 and buoy the drillers and equipment providers with close ties to crude. But John Armitage believed more trouble was ahead.
That uncommon conviction and related bearish bets helped his firm, Egerton Capital LLP, earn $1.5 billion after fees, making Mr. Armitage one of the few to grab a big score in a year that bewildered many on Wall Street.