PROFESSIONAL investors are often portrayed in popular culture as aggressive, hyper-competitive alpha males: think Gordon Gekko in the 1987 film “Wall Street”, or the “Big Swinging Dicks” in Michael Lewis’s “Liar’s Poker”. New research suggests, however, that these fictional characters’ aggressive traits may not be so effective in the real world.

A paper recently published by researchers at the University of Central Florida and Singapore Management University looks at the relationship between testosterone (a hormone associated with competitiveness and risk-taking) and investment performance. Using over twenty years of data on hedge-fund returns and thousands of images collected from Google, the authors find that fund managers with wider faces, a proxy for testosterone levels, tend to trade more frequently, invest in riskier securities and hold onto losing bets longer. As a result, between 1994 and 2015, high-testosterone fund managers (with an average facial width-to-height ratio of 2.10) underperformed low-testosterone ones (with an average ratio of 1.57) by 5.8% per year.

Is there anything investors can do to avoid testosterone-fuelled traders? One approach might be to seek out fund managers with long, thin faces. Or perhaps women and older men who are known to have less testosterone in their bodies. Another would be to bypass human managers altogether. If emotions inhibit traders’ ability to think rationally during market booms and busts, investors might be better off entrusting their money either to static index funds, or to trading algorithms without any emotions at all.