The data comes from the Fed’s Report on the Economic Well-Being of U.S. Households, which found that 49% of adults ages 18 to 29 live with their parents, and another 47% of adults in that same age group received help from someone outside their household to pay an expense—money toward a cell phone bill, general living expenses, or housing costs. Notably, those aren’t the same population, according to Laura Ullrich, director of economics at Indeed Hiring Lab, who has studied household formation trends for years.

“You’ve got to think about this as a Venn diagram,” Ullrich told Fortune. “Forty-nine percent of them are living at home. 47% of them are getting help from someone outside their household, which doesn’t include those living at home. There’s a lot of adult children getting financial support from their parents.”

The data, based on the Fed’s Survey of Household Economics and Decisionmaking (SHED), is troubling for Ullrich, a former senior regional economist at the Federal Reserve Bank of Richmond who has spent years studying household economic trends. Just last year, the stat was closer to 1 in 3 young adults living at home.

“When household formation slows, it slows new household formation, which also makes the age where people typically get married go up, the age people have their first child goes up, fertility rates go down,” Ullrich said. “People buy fewer houses. It impacts local schools. It’s silly to think about if you’re not an economist, but it has much more far-reaching economic implications than just thinking, oh, there’s just a bunch of adults living at home.”

When people stay at home longer or have roommates at older ages, it delays the ages at which they marry, have children, buy homes, and more. This demographic shift also impacts housing markets, school enrollment, and retirement ages.

A ripple effect through the economy

She said the pattern aligns with what has separately been reported about housing affordability, inflation, and the difficulty young adults are having landing a first job. “Given what you see written about housing affordability and current inflation rates, but also the difficulty young adults are having in finding a first job, it’s not surprising to see that number go up.”

The financial-support trend isn’t confined to the youngest adults. Ullrich pointed to a separate figure in the same survey: 26% of adults ages 30 to 44 also reported receiving financial help from outside their household. “It’s not just these much younger adults,” she said. “That percentage is creeping upwards, even over what we think of as the average just-out-of-college fresh adult.” The pattern echoes what Fortune found in a separate Wells Fargo survey this year, where 64% of parents with Gen Z children ages 18 to 28 said their kids still rely on them financially, with support concentrated in essentials like rent and cell phone bills rather than discretionary spending.

Ullrich cautioned that the survey’s wording may be inflating the “living at home” figure for one group in particular: college students. The SHED survey asks respondents simply whether their adult children, age 18 or older, live with them.

“I have a son in college who lives in Virginia most of the year, and I’m thinking, would I say yes or no about him?” Ullrich questioned. “Right now he’s here, so if somebody asked me, I’d probably say yes, but in September I’d probably say no. I do wonder a little bit about how college-age kids are counted.” She noted the underlying trend is real regardless. “This has been going up over time, there’s no doubt about that.”

The same survey also tracks how financially comfortable households say they feel. According to FRED’s series on the measure, the share of households reporting they were “doing okay” or “living comfortably” spiked to 78% in 2021, which Ullrich attributes to pandemic-era stimulus payments and enhanced unemployment benefits rather than any underlying strength. It has held at 72-73% every year since. “I wouldn’t take that as a real signal. To me that’s an outlier,” she said. “What’s actually more amazing to me is that it hasn’t gone down more, given how high inflation has been.”

She added that, in the survey, the decline in financial comfort is concentrated among those without a high school diploma, while those with a diploma have held roughly steady since 2016. This is evidence, she said, of a K-shaped economy playing out generationally as well as by income.

Ullrich said this broader trend will structurally alter the economy and is likely to show up for years in migration patterns and lifetime earnings as much as in survey data. Young adults who expected to move to major cities for their first jobs are instead staying closer to home while they search, something she said could be financially sound for individual families even as it reshapes broader economic patterns.

“These decisions at the micro level just impact households and family decisions, but at the macro level they do impact more things: home buying, fertility rates, all the things we talked about. When you have that larger percentage living at home, you will see some of those impacts.”