NEW YORK (AP) — There is a clear trend home prices declines are moderating — another sign the beleaguered housing market is stabilizing, according to data released Tuesday.

While the Standard & Poor's/Case-Shiller index of 20 major cities tumbled by 18.1 percent in April from the year before, it marked the third straight month the decline was not a record. And yearly losses in 13 metros improved compared to March.

"The stock market bottomed in March and measures of consumer confidence have turned upward. This report shows that these better spirits are also appearing in the housing market," said David M. Blitzer, chairman of the S&P index committee.

But rising foreclosures fueled by layoffs could derail a meaningful turnaround. The number of homeowners at least two months behind or in foreclosure jumped in the first quarter from the previous quarter, a Treasury Department report said Tuesday.

Defaults from borrowers with good credit contributed to much of the increase in seriously delinquent loans, echoing data last month from the Mortgage Bankers Association. As the recession claims more jobs, borrowers in good standing are more likely to miss their mortgage payments.

Efforts to modify home loans have been slow and easily outpaced by the number of new delinquencies. In the first quarter, loan companies modified 185,156 mortgages, up 55 percent from the previous quarter. But the number of foreclosures in process increased to 844,389, up 22 percent.

And nearly one in four borrows who received a mortgage payment reduction fell behind again within six months, the report found.

"So far (the modification program) isn't showing large numbers, which tells me that it's not working and that's a problem," said Patrick Newport, an economist with IHS Global Insight.