WASHINGTON — A soaring U.S. stock market and healthy home price gains lifted Americans’ net worth to $98.7 trillion in the final three months of last year, a gain that could increase household spending.

The value of U.S. stock portfolios jumped $1.3 trillion in the October-December quarter compared with the previous three months, the Federal Reserve said Thursday. That figure includes stocks held through mutual funds and in retirement accounts.

Home values, which make up the bulk of middle-class wealth, increased $500 billion.

The figures are at a record high, though they are not adjusted for inflation or population growth. They predate February’s sharp gyrations in the stock market, though stock market indexes are still up about 2 percent this year.

The solid gain in wealth could make many Americans more confident and lead them to spend more, which typically fuels economic growth.

Economic research has found that in the past, people spent roughly 3 to 5 cents of every dollar in additional wealth they accumulated. Since the recession, however, Americans have become more cautious with their wealth. Economists now estimate that roughly only 1 penny for every dollar is spent.

Overall U.S. wealth has grown steadily since the recession ended nearly nine years ago, but it isn’t widely shared. Edward Wolff, an economist at New York University, calculates that in 2016, average household wealth had fully recovered from the Great Recession and was 7 percent higher than it had been in 2007.

But median wealth was still 34 percent below its pre-recession level, Wolff calculated. The median is the point where half of households are richer, and half poorer, and gives a better sense of how typical families have fared. Average wealth was pulled up by the richest households.

Americans have become more confident about the economy and are spending at a robust pace.