The rich are getting richer, and this trend has become so pronounced that even the wealthiest Americans, who have reaped the lion’s share of economic gains in recent years, are sounding the alarm bell.

“I think the greatest issue of our time is the disparity of wealth and the problems that exist for the lower 40% of the population,” said Ray Dalio, founder of Bridgewater Associates. Bridgewater is the world’s largest hedge fund, which about $160 billion in assets. According to Forbes, Dalio himself is worth about $17 billion.

“If you carve out that lower 40%, not only has there been no income growth, but death rates are rising because of opiate use, suicide, and because they’re losing jobs,” Dalio said. “This is the biggest issue of our time—the biggest economic issue, the biggest political issue, and the biggest social issue.”

According to data released by the Centers for Disease Control and Prevention, the rate of drug overdose deaths in the U.S. in 2015, adjusted for age, was more than 2.5 times the rate in 1999. Accessibility to prescription drugs is a major factor behind this trend; last month, President Donald Trump said he would officially declare the opioid crisis “a national emergency.” Separately, according to one recent study, U.S. income inequality grew by nearly 30% between the early 1960s and 2014, with a decline in labor unions seen as a major factor.

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Dalio—who recently made waves by declaring the cryptocurrency bitcoin to be in a bubble, and by reducing Bridgewater’s risk levels because he doesn’t think partisan conflicts in Washington will be”handled well”—made his comments at an event for Grameen America, a nonprofit microfinance organization where he is a director emeritus.

Grameen was founded by Muhammad Yunus, who won a Nobel Peace Prize and Presidential Medal of Freedom for his work in microfinance. The organization’s model is to identify women who lack traditional forms of capital, credit, or collateral, but still have aspirations of entrepreneurship—for example, in food services or small shops. The women are put into groups of five, pass a course, and then decide among themselves which two of them will first receive a loan from a bank. If those two don’t repay the loan, the other three won’t receive one of their own, for their own businesses.

“I know of no model that is better than this one,” Dalio said. “The women all root for each other and hold each other accountable, and they make it work all around. Not only does this model fund itself, but it has an impact on the people who need the money the most.”

He added that “my goal and aspiration is to move this to a national program, because I think our country needs it.”

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Grameen currently operates in 13 U.S. cities, including multiple neighborhoods in New York City. Over the past 10 years, it has disbursed more than 400,000 loans, totaling more than $1 billion.

“The dollars keep coming back and back around,” Dalio said. “If you donated $1,000 five years ago, you essentially donated $12,000 because it has been repaid and lent back out 12 times. Not since the miracle of loaves and fishes as anyone created so much out of nothing to help people.”