MONDAY, Jan. 12 (HealthDay News) -- For all those whose ring finger far outstretches their index finger, British researchers have pinpointed the perfect job: high-volume stock trader.

According to a new study, having a relatively long ring finger augurs well for success in those high-stress financial arenas where fast thinking, good reflexes and good old-fashioned guts matter most. A lengthy fourth digit, the authors note, indicates greater exposure to testosterone in the womb, which in turn gives what they call "high-frequency" traders a biological leg up by encouraging the development of the right mix of mental attitude and physical skills for making money in a cutthroat business.

The finding is reported in this week's issue of the Proceedings of the National Academy of Sciences.

"I used to run a trading desk on Wall Street," explained study author John M. Coates. "During that time I had noticed -- during the dot-com bubble -- that the traders were displaying almost clinical symptoms of mania. They were delusional, euphoric, had a diminished need for sleep, and displayed feelings of overconfidence. You couldn't get them to shut up or put a normal sentence together. And I began to think that something physiological was going on."

Coates hypothesized that the chemical driving trading behavior was one of the human steroids, which he described as "massively powerful" in their ability to affect mood, memory and cognition. He zeroed in specifically on testosterone because the relatively few female traders on the floor did not display the same manic behavior as the men.

"So I left Wall Street, in large part to look into the hypothesis that testosterone was driving trader behavior during the bull market," said Coates, who went on to conduct his work as a research fellow with both the Judge Business School and the department of physiology, development and neuroscience at the University of Cambridge in England.

To explore the notion, Coates and his colleagues analyzed 20 months of profit-and-loss records involving 44 male traders who worked on the London trading floor. When the study began, the floor was home to about 200 traders, of whom just three were women.

All the participants were specialized in what's known as "high-frequency trading." In contrast to slower-moving, research-based trading -- the type that occurs with mutual, pension and hedge fund management, for instance -- the authors noted that high-frequency trading involves the lightning-fast buying and selling of securities at values as high as 1 billion British pounds (about $1.49 billion).

Coates and his team observed that this particular form of financial wheeling and dealing is very physically demanding. Rapid-fire trading executions, they said, require extreme concentration, visual vigilance, strong motor-eye coordination and quick reaction time, alongside extreme confidence and a willingness to engage in substantial risk-taking.