The world’s richest have amassed an eye-watering stockpile of $15.1 trillion—and their heirs are set to take over a third of the global billionaire fortune in the coming decade. Women and Gen Xers are set to take home the largest slice of the pie.

About 5,000 spouses and adult children will inherit $6.6 trillion of billionaire wealth by 2035, according to a recent report from wealth-intelligence firm Altrata.

More and more billionaires are inheriting part of their wealth thanks to the growing frequency of inter-generational estate transfers and family gifting. And within the next 10 years, new billionaire records could be broken as thousands more receive wealth from the current group of 3,795 billionaires—an all-time record.

Looking ahead, women stand to gain the most from the great wealth transfer. Only 13% of current billionaires are women—but as men over the age of 60 dominate the ultra-rich cohort, more than 1,235 female spouses (representing 90% of billionaire partners) will inherit a sizable chunk in the next decade. Altrata says the mega-wealthy gender gap will narrow over time, and as their fortunes grow, there will be “greater diversity” in decision-making and ownership.

“[Rising female billionaire representation] could also spur more entrepreneurial activity and venture capital involvement among the wealthy female class, drive an expansion of female-focused wealth management services, and influence large-scale philanthropic endeavors,” the report says, adding that billionaire women are more involved in non-profit sectors than men are.

Thousands of others stand to ride the wave of the trillion-dollar wealth transfer, including billionaires’ siblings, grandchildren, and organizations tied to philanthropic endeavors like non-profits and education institutions.

But their adult children will be some of the biggest beneficiaries—especially Gen Xers.

Gen X children will be among the biggest inheritors

Baby boomer billionaires spent decades grinding it out and stockpiling their successes—and now, their grown-up children are getting in on the action. Altrata found that 23% of expected adult child heirs, typically aged around 48, already work with their ultra-rich parents in the primary family business. That means the latchkey generation is now poised to inherit a massive share of that wealth.

“Attention is often focused on young millennial and Gen Z heirs, but the Gen X demographic is by far the most numerous in line to inherit from their wealthy parent(s),” the Altrata report says.

Rather than simply receiving cash deposits, adult heirs are set to take on a combination of real estate and shares in listed companies, private businesses, and investment portfolios.

Then there’s carrying on their parents’ entrepreneurial legacy: Some billionaire children will lead family businesses that have passed down through generations, from manufacturing and consumer goods to finance and retail.

And when wealth falls into their laps, these billionaire heirs are expected to shake things up.

Young and middle-aged inheritors are more digitally savvy and activism-oriented than older generations. New technologies, responses to climate change, and “impact investing” could be huge areas of interest for these rich adult children, Altrata explains, which could run awry with how their older parents want to spend their fortunes.

Geopolitical tension and AI will shape the great wealth transfer

As thousands of spouses and adult children step into wealth in the coming decade, they’ll be up against major headwinds.

Altrata predicts that “further erosion of the global rules-based order,” climate pressures, tech transformation, and changes to the global economy in the AI era will shape the years ahead.

“This substantial transfer of family wealth is set to occur in a world of rising complexity, tense geopolitics, and major environmental and technological change,” the report says. “A more unpredictable multipolar world, with shifting centers of power and influence, will complicate the succession-planning and wealth-preservation strategies of the global billionaire class.”

However, there is still opportunity in the chaos of the great wealth transfer. Altrata says that volatility gives next-gen billionaires new opportunities in business, investing, and philanthropy.

As trillions of dollars change hands, inheritors won’t just take on their family fortunes—they’ll also have the chance to reshape how that wealth is invested, spent, and put to work.