Researchers at the University of Cambridge in England report that men with longer ring fingers, compared to their index fingers, tended to be more successful in the frantic high-frequency trading in the London financial district.
Indeed, the impact of biology on success was about equal to years of experience at the job, the team led by physiologist John M. Coates reports in Monday's edition of Proceedings of the National Academy of Sciences.
The same ring-to-index finger ratio has previously been associated with success in competitive sports such as soccer and basketball, the researchers noted.
The length ratio between those two fingers is determined during the development of the fetus and the relatively longer ring finger indicates greater exposure to the male hormone androgen, the researchers noted.
Previous studies have found that such exposure can lead to increased confidence, risk preferences, search persistence, heightened vigilance and quickened reaction times.
In a separate study last year, Coates and colleagues reported that the hormone that drives male aggression and sexual interest also seemed able to boost short term success at finance.
They studied male financial traders in London, taking saliva samples in the morning and evening. They found that those with higher levels of testosterone in the morning were more likely to make an unusually big profit that day. Testosterone, best known as the male sex hormone, affects aggression, confidence and risk-taking.
In the new study, the researchers measured the right hands of 44 male stock traders who were engaged in a type of trade that involved rapid decision-making and quick physical reactions.
Over 20 months those with longer ring fingers compared to their index fingers made 11 times more money than those with the shortest ring fingers. Over the same time the most experienced traders made about 9 times more than the least experienced ones.
Looking only at experienced traders, the long-ring-finger folks earned 5 times more than those with short ring fingers.
While the finger ratio, showing fetal exposure to male hormones, appears to signal likely success in high-actively trading that calls for risk-taking and quick reactions, it may not indicate people who would do well at other sorts of financial activities, the researchers said.
Some traders require additional skills on dealing with clients and sales workers.
And the advantage may even reverse for some, Coates team said, such as traders taking a more analytical and long-term approach to the markets.
One study, which looked at average finger ratios in university departments found that faculty from math, science and engineering exhibited longer index finger ratio, rather than ring finger, they noted.