NEW YORK(Reuters) - When it comes to industries, Wall Street is about as male-dominated as they come. So many people just assume that men are better investors.

A woman walks on Broad St. past the New York Stock Exchange during the morning commute April 30, 2014. REUTERS/Brendan McDermid

And they would be wrong.

According to new data from financial services giant Fidelity Investments, women are actually superior investors. In sifting through more than 8 million investment accounts, Fidelity discovered that women not only save more than men, 0.4 percent, their investments earn more annually, also 0.4 percent.

“It is a double whammy,” says Alexandra Taussig, Fidelity’s senior vice president for women investors. “The myth that men are better investors is just that - a myth.”

Those differences may seem slight at first. But extrapolated over a lifetime of saving and investing, the disparity at retirement age is anything but minor. For a 22-year-old starting out with a salary of $50,000 a year, a woman investor will outpace her male counterpart by more than $250,000.

Even more revealing about general attitudes is Fidelity’s companion “Women and Money” survey, which asked participants which gender was better at investing its money. The outcome: Barely 9 percent of people said women.

What is it, exactly, that makes women better investors? One factor, Fidelity said, is that men are 35 percent more likely to make trades, which means that trading fees eat away at their portfolios more than they do women’s.

Women also save more in the first place - almost a full percentage point annually - in workplace 401(k)s and individual vehicles such as IRAs and brokerage accounts, Fidelity found.

Another advantage: Women assume less risk, such as not loading up entirely on equities. They also invest more in vehicles like target-date funds, whose automatic allocations make for smarter diversification, Fidelity said.

The resulting gender outperformance gibes with a study by academics Terrance Odean (University of California, Berkeley) and Brad Barber (University of California, Davis), who also found that women outperform men, by roughly 1 percent a year.

If you want to invest like a wonder woman, that means shifting to a long-term focus, saving more up front and giving up on trying to time the market with brilliant trades.

“Men regard their stock picks as a sport that comes with bragging rights, and that is what gets them into trouble,” said George Gagliardi, a financial planner in Lexington, Massachusetts.