Hedge-fund managers with high testosterone underperform those with low testosterone by 5.8 percent a year, a study says. : After years of underperformance, researchers may have discovered what's plaguing the hedge-fund industry: too much testosterone. Hedge-fund managers with high testosterone underperform those with low testosterone by 5.8 percent each year, according to a study conducted by University of Central Florida and Singapore Management University. The researchers used software to measure the facial width-to-height ratio — proven to be a proxy for testosterone levels — of more than 3,000 hedge-fund managers.