The most famous battle of the sexes might have been the tennis match between Billie Jean King and Bobby Riggs in 1973.

A charismatic showman, Riggs was also a toe-curling chauvinist.

The former Wimbledon champion mocked Women tennis players, until Billie Jean King forced the guy some humble pie.

Some argue that Bobby Riggs lost because he was fifty-five years old. But there’s at least one alpha arena where women quietly reign supreme.

Investing.

I first began noticing this after giving Investment talks at businesses and international schools. I explained the importance of a low-cost portfolio of index funds. And I outlined the biggest enemies: fear, greed and speculation. If investors could keep those demons at bay, they could do well.

Often, I returned a few years later to speak at those same places. During one-on-one conversations with couples, I asked how things were going. The conversations typically went something like this:

“Have you been adding regular money to your index funds and have you avoided speculation?”

“We started off alright, but then we added some…”

Sometimes, it was crypto. Other times, it was a “hot” stock, an actively managed fund or a private equity “opportunity.” Unfortunately, these speculations typically went sideways, or worse.

Then I asked, “Whose idea was it to get into this thing?”

It was almost always the man’s.

Certified financial planner, Edward Goodfellow, sees much the same thing. The author of 7 Steps to a Better Portfolio says his clients Doug and Kathy (he changed their names to protect their privacy) demonstrate the typical male/female dynamic.

Edward Goodfellow

“Doug often picks up media talking points,” says Edward. “He advocates for an investment or economic outcome that is based on his opinion of market noise.” His wife, Kathy, is less confident. “Kathy asks more questions and seeks more objective advice. She isn’t always always looking for investment shortcuts the way Doug does.”

Portfolios with Higher Stock Allocations typically beat balanced portfolios. But as I’ve written before, how an investment allocation performs and how people perform with their allocations are two different things.

Men, for example, typically have higher stock allocations than women. As a result, they should perform much better, especially during periods when stocks soar. But they don’t.

A ten year study from Fidelity compared annualised returns from 5.2 million self-directed accounts from January 2011 to December 2020. Despite taking lower investment risks, the average woman’s account earned higher returns than the average man’s account.

Mike and Sarah Beatty understand why. The couple lived in Qatar for eight years, before recently moving back to the UK. “We invest in index funds,” Mike says. But as the founder of StrongHomeGym.com, Mike is man enough to know that he and Sarah fit the typical male/female investment profile. When things have gone sideways, Mike knows who’s to blame.

“I’ve speculated on cryptocurrency,” he admits. “And this picture sums up exactly what my wife thinks about that.”

Mike and Sarah Beatty

Fidelity isn’t the only investment firm that says women account holders beat guys. Vanguard says its female investors beat their male counterparts in a study from 2005 and 2010.

Economic professors Brad Barber and Terrance Odean found much the same thing. They studied 35,000 household brokerage accounts between 1991 and 1997. But they compared apples to apples. For example, they compared men’s high-risk portfolios to women who also took high risks. They also compared men’s low-risk portfolios with women’s low-risk portfolios. When the women and men took the same amount of risk, the women beat men by 3 percent per year.

Between 2010 and 2015 Wells Fargo compared investment performances, too. They also found that women beat men. When they adjusted for risk, women pulled even further ahead.

This isn’t news to Gary Menton, who admits his partner, Cathy Turchan, is a better investor than him.

“Cathy has turned out the noise,” says Gary. “She’s in it for the long haul. I have been more reactive to the [market and economic] noise and tend to buy and sell more quickly.”

Gary Menton and Cathy Turchan

Men’s tendency to trade more frequently is part of the problem, according to the Wells Fargo study. Their research says men were also six times more likely to jump from 100 percent stocks to 100 percent bonds. In other words, men are more likely to try to time the market.

A 2005 Merrill Lynch investment survey also says men are twice as likely to charge into an investment without doing research.

But investing shouldn’t be a battle of the sexes. Instead, it should be a cooperative effort. There’s no room for Bobby Riggs-like overconfidence.

After all, Bobby did lose.

Andrew Hallam is the best-selling author of Millionaire Expat (3rd edition), Balance, and Millionaire Teacher.