For years, David Einhorn’s investors did not seem to mind his unusual ways — the aloofness toward clients, midday naps, unpopular stock picks, late nights on the town. Until the billionaire hedge fund manager fell into a slump.

After more than a decade of winning on Wall Street, Einhorn’s Greenlight Capital has shrunk to about $5.5bn in assets under management, his investors estimate, from a reported $12bn in 2014, and his investments are struggling.