Americans are more worried about having the wealth and income necessary to fund their retirements than they were at the end of the Great Recession, according to a Pew Research Center survey released on Monday.

Despite a slowly improving economy and a rebounding stock market, nearly four in 10 Americans are not confident that they will have the financial wherewithal to retire. A similar report in 2009 found that one in four adults were concerned that they would not be financially ready for retirement, Pew said.

Strikingly, that anxiety is now most pronounced among young adults, a marked shift over three years ago when workers in their 50s were most worried that they would outlive their retirement savings. More than half of adults aged 36 to 40 say that they are not confident that their nest eggs will last through retirement, three times the share who expressed similar doubts in 2009.

Pew researchers said the shift reflects seismic changes that have shaken the economy in recent times. Saddled with sharply declining home values, the median wealth of adults aged 35 to 44 was less than half of what it was for people who were in that age group in 2001, Pew said.

“The median net worth of this group has fallen at a far greater rate than for any other age group both in the past 10 years and since the beginning of the Great Recession,” the report said.

By contrast, people aged 55 to 64 lost just over a fifth of their wealth in that time period, according to Pew, which polled 2,508 adults in its survey.

The retirement concerns of younger workers are compounded by the reality that younger workers are less likely than their older counterparts to have guaranteed pensions, meaning they have to rely on their own assets to supplement Social Security in retirement.