Among male high-frequency financial traders, those whose ring fingers are longer than their index fingers tend to be more successful, according to a British study.

Prior research has shown that the longer ring finger is a significant indicator of higher exposure to prenatal androgenic steroids.

The new Cambridge University study found that traders with high level of prenatal androgens — as indicated by the ratio of index- to middle-finger length — made on average six times as much as those exposed to low levels and remained traders for longer.

The study, authored by Canadian John Coates, Mark Gurnell and Aldo Rustichini, monitored the profit and loss statements of 49 London men engaged in high-frequency trading over 20 months and compared them to the relative lengths of their ring fingers.

It will be published in Tuesday's edition of the Proceedings of the National Academy of Sciences.

"The success and longevity of traders exposed to high levels of prenatal androgens further suggests that financial markets may select for biological traits rather than rational expectations," says the study.

Prenatal androgens organize the developing brain, increasing its sensitivity to the effects of circulating testosterone later in life. Higher sensitivity to circulating testosterone can result in increased confidence, risk preference, higher reaction times and search persistence — traits that can be very useful to high-frequency traders, the study notes.

Findings specific to type of trader

"This is one type of specific trading — very short-term trading," Coates told CBC News. "It's a really brutal section of the market where success come mainly from speed."

The results, he said, have to be taken with a grain of salt.

"I don't want people to draw the conclusion … that to succeed in the financial world you need a lot of testosterone," Coates said. "Testosterone is a destabilizing influence. It exaggerates bull markets."

The researchers also found that a trader's experience contributes about as much to a high-frequency trader's long-term profit and loss statement as biology.

The study notes that its findings are likely to be replicated among day traders and local traders on the floors of stocks and futures exchanges.

But the researchers say their findings could be weakened, perhaps even reversed for those who — like arbitrage traders or hedge fund managers — have to make more analytical, long-term investments.

"Investors and arbitrageurs try to profit from market trends, whereas high-frequency traders make their money by trading temporary variations around the trend," the study notes.

The researchers aren't sure what governs levels of prenatal androgens.

"It may be genetic. It looks like it's mostly coming from the fetus, but it may be coming from the mother," said Coates.