(Bloomberg News) The financial crisis wiped out 18 years of gains for the median U.S. household net worth, with a 38.8% plunge from 2007 to 2010 that was led by the collapse in home prices, a Federal Reserve study showed.

Median net worth declined to $77,300 in 2010, the lowest since 1992, from $126,400 in 2007, the Fed said in its Survey of Consumer Finances. Mean net worth fell 14.7% to a nine-year low of $498,800 from $584,600, the central bank said. Almost every demographic group experienced losses, which may hurt retirement prospects for middle-income families, Fed economists said in the report.

"The impact has been a massive destruction of wealth all across the board," said Lance Roberts, who oversees $500 million as chief executive officer of Streettalk Advisors LLC in Houston. "What you see is an economy that's really very, very stressed for the bottom 60% to 70% of the population that's struggling just to make ends meet."

The declines in household wealth in the course of the longest and deepest recession since the Great Depression have held back the consumer spending that makes up about 70% of the economy.

The Fed has already taken unprecedented steps to boost the economy as it battled the 18-month recession that ended in June 2009, cutting its key interest rate almost to zero and purchasing $2.3 trillion in debt to lower long-term borrowing costs. Even so, the jobless rate has stayed above 8% since February 2009, compared with the central bank's long-range goal of 4.9% to 6%.

"Although declines in the values of financial assets or business were important factors for some families, the decreases in median net worth appear to have been driven most strongly by a broad collapse in house prices," the Fed economists wrote.

The S&P/Case-Shiller U.S. Home Price Index fell 23% in the three years through December 2010. The Standard & Poor's 500 index lost 14% in the same period.

The proportion of families with retirement accounts decreased 2.6 points to 50.4% during the period, wiping out much of the 3.1 percentage-point increase over the prior three years, the report said.

"The most noticeable drops in ownership were among families in the middle-income, middle-wealth and middle-age groups," the economists said. "Retirement accounts had been growing in importance as a supplement to Social Security and other types of retirement income, and the decrease in ownership in the past three years may represent a setback."

Fed economists conduct the surveys every three years to produce a snapshot of household balance sheets, pensions, income and demographics that's more detailed than broader reports about the economy.