By Katherine Mangan

Female M.B.A. students with higher testosterone levels are more likely to feel comfortable taking financial chances and to choose risky careers like investment banking or trading, according to a new study by Chicago researchers.

A paper describing the study, "Gender Differences in Financial Risk Aversion and Career Choices Are Affected by Testosterone," was published in Monday's edition of the Proceedings of the National Academy of Sciences.

The research was conducted by Paola Sapienza, an associate professor of finance at Northwestern University's Kellogg School of Management; Luigi Zingales, a professor of entrepreneurship and finance at the University of Chicago Booth School of Business; and Dario Maestripieri, a professor in comparative human development at the University of Chicago.

"In general, women are more risk averse than men when it comes to making important financial decisions," says Ms. Sapienza. That, she says, can affect their career choices.

In the study, in which testosterone levels were tested in nearly 500 M.B.A. students enrolled in a required course at the University of Chicago, 57 percent of the male M.B.A. students ended up choosing high-risk financial careers like investment banking or trading, while only 36 percent of the female M.B.A. students did.

The reason, the authors concluded, had to do with men's generally higher levels of testosterone.

"We concluded that it is the testosterone and not the gender that is associated with risk taking," Ms. Sapienza said in an interview last week.

In their study, women with higher testosterone levels were more comfortable taking risks. The link applied to men with low to moderate levels of testosterone, but for those with very high testosterone levels, differences in risk taking were not apparent.

At moderate levels of testosterone, men and women with similar levels had similar tolerance for risk.

The study was based on completed responses from 460 students—320 men and 140 women. The students' testosterone levels were determined from saliva samples collected in the fall of 2006. (The course was required, but the lab test was optional). The students' career choices were noted in the spring of 2008.

The researchers also measured the lengths of the students' index and ring fingers, based on the theory that index-to-ring-finger ratios are related to prenatal testosterone exposure (longer ring fingers generally point to more testosterone).

The students also played a computer game that measured their appetite for risk. It included a series of questions in which students were repeatedly asked to choose between a guaranteed monetary award or a lottery whose potential payout grew as the game progressed.

Not surprisingly, the men were more likely to have higher testosterone levels and to choose the risky lottery more often than the women did.

That doesn't mean that testosterone-challenged women are less successful in fields like investment banking, Ms. Sapienza says. "We've seen many examples recently of fund managers taking excessive risks with their clients' money."

Asked how, as a woman in finance, her own testosterone levels measured up, Ms. Sapienza laughed and said she had been too busy testing students to test herself. But if her long ring finger is any indication, she wouldn't be timid about jumping in on the trading floor.