Earnings growth and low interest rates may not be around forever to sustain this nine-year-old bull market. So what's the next option to keep it alive? Women.

It should come as a shock to few that more equity in the workplace breeds better outcomes, but new data from S&P Global suggested that improved outcome could be worth trillions of dollars to the U.S. equities market.

S&P found that increasing the women's labor force participation rate to a level of some other advanced countries would add an average of 0.2 percentage points annually to the gross domestic product of the U.S. over the next 10 years. That means a U.S. economy with more women working would be $455 billion bigger than what S&P expects at the current baseline forecast for growth during that period.

According to S&P, an additional 0.2 percentage point gain in GDP per year translates to an additional 0.7% gain on the S&P 500 Index annually. "All else being equal, the additional estimated economic expansion would increase U.S. stock market capitalization by $2.87 trillion in a decade," S&P analysts wrote.

Source: S&P Global
Source: S&P Global

"Based on the historical sensitivity of stock markets to economic expansion, an acceleration of U.S. output at the pace we calculate under increased female workforce participation could help extend a historically long global bull run in equities, adding a whopping $5.87 trillion to global market capitalization in the next 10 years," S&P said.

While the broader market would undoubtedly benefit from more women entering the workforce, the information technology sector could be among the biggest beneficiaries. That 0.2 percentage point gain in GDP translates to an additional 1.1% annual gain in the info tech sector, S&P found.

Source: S&P Global
Source: S&P Global

Utilities would be the least impacted by a female-driven GDP boost. S&P found that the sensitivity of utility stocks to GDP growth is 2.2-to-1, meaning an extra 0.2 point of growth in GDP adds 0.4% to total return growth for that sector.

Beyond just the U.S. stock market, adding more women to the U.S. labor force pushes global equities higher, too. Historical averages indicate that a single-percentage-point gain in U.S. GDP boosts German equities by 4%, Chinese equities by 6.2% and Korean equities by 9.3%.

Source: S&P Global
Source: S&P Global

"The sensitivity of Korea is so great that in 10 years its stock market value could grow from the smallest of the major countries in the world to the third-largest, surpassing China, by adding more women to the U.S. workforce," S&P said.

While Wall Street has relished strong U.S. jobs reports month after month, unemployment rates and job additions don't tell the full story. Less than 63% of the working-age population is currently employed or actively seeking work, according to the U.S. Bureau of Labor Statistics, putting the labor force participation rate near a four-decade low.

"For years, the surge of women entering the workforce largely offset the slow attrition of male labor force participation," S&P said. "But since the turn of the millennium, women's participation has also declined, to just 57% from roughly 60% in 2000."

That shifting trend has impacted U.S. labor markets hard and fast. As recently as 1990, the women's labor force participation rate in the U.S. was near the top among other developed nations. While participation among women in the U.S. has shrunk, other countries have watched their female workforces balloon. The U.S. was in 2016 ranked 20th out of 22 developed countries in a measure of women's labor force participation.

"All told, if the U.S. were to follow the lead of many other developed countries and implement policies that encourage women to enter and remain in the workforce, the effect could reverberate globally, supporting a stock market boom far greater than the economic growth itself," analysts concluded.

Expert Advice for a Risky Market. We asked top experts from Bank of America, Fisher Investments, Invesco and Wells Fargo what smart investors should do right now. Click here and register for free to watch what these market watchers recommend.

More from World

Jim Cramer's Advice for Investors During a Bear Market

Jim Cramer's Advice for Investors During a Bear Market

FAANGs, Retail, Housing, Boston Scientific & Renault - Five Things You Must Know

FAANGs, Retail, Housing, Boston Scientific & Renault - Five Things You Must Know

Striking Options: Volatility, Nasdaq, & Treasuries

Striking Options: Volatility, Nasdaq, & Treasuries

Jim Cramer Says That This Is a Question All Investors Must Ask Themselves

Jim Cramer Says That This Is a Question All Investors Must Ask Themselves

Carlos Ghosn, Apple, US-China Trade, Bitcoin and Pfizer - 5 Things You Must Know

Carlos Ghosn, Apple, US-China Trade, Bitcoin and Pfizer - 5 Things You Must Know