I hate to kill the pseudo-feminist buzz but this article references two well-known studies that measured morning testosterone and cortisol levels in traders and found that higher testosterone equated to greater profits (and risks).
http://www.drugs.com/news/testosterone-levels-among-financial-traders-affect-performance-11767.html
http://www.drugs.com/news/testosterone-levels-among-financial-traders-affect-performance-11767.html