Bad decisions by bad-boy stock traders. There's plenty of blame to go around for the sorry state of the U.S. economy and financial markets, but people don't often put together the overwhelmingly maleness of Wall Street traders with the testosterone-fueled desire for risk-taking and challenge.

Except for John M. Coates, a research fellow in neuroscience and finance at Cambridge and a former Wall Street trader. I guess that places him in the "neuroeconomics" category. He has a fascinating theory about why males seem

According to this article, stock traders may be the victims of the "winning effect."

When two predators battle it out, the winner emerges with increased testosterone levels; the loser with diminished testosterone.

Fuelled on powerful steroids, the predator picks another fight. He wins again, feels elated and goes after an even stronger opponent. After a few victories, he starts to get sloppy, overconfident and cocky. "Animals continue having successful rounds of winning until they take stupid risks," says Dr Coates.

This next part goes in the "too good to check" file.  According to the  article, by Helen Kirwan-Taylor, when Coates gave 17 London stock traders oxytocin, however, they became calmer and less likely to do something dumb. 

It sure makes sense, and I sure wish it was true. But Dr. Coates told me via email that this detail is false. Can someone please do this study? Please?

This article from the Why Files provides more color. And here's a link to the abstract of his study:
Endogenous steroids and financial risk taking on a London trading floor, John M. Coates and J. Herbert, PNAS, Apr. 22, 2008