According to UBS’s Global Wealth Report 2024, $83.5 trillion of wealth will be transferred to younger people within the next 20 to 25 years. And a significant chunk of this sum currently held by the boomer generation will be passed on within the next decade.

That is because people over age 75 (boomers and the Silent Generation) currently hold around a fifth of the world’s overall wealth. However, given that life expectancy tends to fall between ages 82 and 86, UBS wrote that this shift may occur sooner rather than later.

Currently, individuals passing on their wealth are just over 84 years old and are giving it to those around 59 (Gen X), UBS found. However, as the next 10 years unfold, wealth will be passed to younger generations, leading analysts to predict that millennials will become the “wealthiest generation in history.”

But while inheritance is often thought of as a downward chain from older to younger, there is also a horizontal element to inheritance.

UBS points out that given an age gap between couples, spouses often outlive their other halves, meaning that for an average of four years, one individual will often inherit a sum of money before passing it on.

“In total, an estimated $9 trillion of wealth will be transferred intra-generationally—or horizontally—between spouses,” UBS wrote, adding that this trend in the Americas is more pronounced than anywhere else on the planet.

It’s highly likely that wives in heterosexual married relationships are more likely than their husbands to be widowed and, thus, inherit the wealth.

This is due to several factors.

First, American women have an average life expectancy of 80.2 years compared to 74.8 years for men, so even if couples married at the same age, wives would be more likely to outlive their partners.

However, women are likely to be younger than men when they get married. According to Census Bureau data, the average age of a man when he first marries is a little over 30, whereas for women, it is around 28.

These factors result in the fact that in the coming wealth transfer, more than 10% of the $83.5 trillion sum will be passed on by women.

Americans set to get wealthier

The report from UBS also had some good news for consumers.

Not only is it easier to climb the wealth ladder than it is to fall back down it, but in the U.S. individuals across the income spectrum are set to get wealthier.

The result of this upward swell in wealth means that in America there will be more millionaires come the end of the decade than there are currently, meaning even greater sums are set to be passed on.

UBS found the chance of an individual upgrading from the lowest wealth bracket (under $10,000) was 61.7%. Those in the consecutive wealth bracket (who have between $10,000 and $100,000 in assets) also have a 37.1% chance of ascending to the next tier, with assets of between $100,000 and $1 million.

Those in the highest wealth bracket with more than $1 million have a 51.6% risk of falling out of that category into one of the lower tiers, though this eventuality is outweighed by the likelihood of those moving up.

The result is that the number of millionaires who call the U.S. home is expected to grow by 16% between 2023 and 2028, UBS adds, a leap from just under 21 million wealthy individuals to more than 25.4 million millionaires.

But it’s not just those with seven-figure fortunes who are growing their wealth: People across the asset spectrum are seeing their prosperity grow.

UBS found that between 2000 and 2023 the percentage of people in the lowest wealth bracket halved from over 75% to less than 40%, while individuals are also three times more likely to be classed as millionaires.

In the U.S., inequality still has some way to go, the report adds.

Its inequality index found that while Americans are more equal in 2023 than in 2000, the improvement is marginal.

Perfect equity on its index would represent a score of 0 on a spectrum of up to 100. The U.S. scored 76 in 2008 and 75 in 2023.

A version of this story originally published on Fortune.com on July 12, 2024.