NEW YORK (CNNMoney.com) -- National U.S. home prices fell a record 15.4% in the second quarter compared with last year, according to a report released Tuesday.

The latest S&P/Case-Shiller national home price index is down 18.2% from its peak in the second quarter of 2006, and there are no signs that the pace of home-price declines is easing. The second-quarter loss was even larger than the record 14.2% drop posted in the first three months of 2008.

Both the Case-Shiller 10-city index (down 17%) and 20-city index (down 15.9%) also posted record year-over-year losses in the second quarter.

A small piece of good news: In June the pace of monthly declines slowed ever so slightly compared with May. Prices for the 10-city index declined 16.9% year-over-year and the 20-city index was down 15.8%.

NEW YORK (CNNMoney.com) -- The government offered more discouraging news about the housing sector on Tuesday, reporting that new home sales rose slightly in July only after revising the previous month's number sharply lower.

Sales for July came in at a seasonally adjusted annual rate of 515,000, up 2.4% from 503,000 in the previous month, the Census Bureau reported. Last month, Census had put the June figure at 530,000.

The change marks the fourth of the past five reports that Census has slashed the previous month's number. The trend worries economists who say a hoped-for stabilization of the housing market remains elusive.

NEW YORK (CNNMoney.com) -- The problems plaguing mortgage finance giants Fannie Mae and Freddie Mac could cause another big financial drain on banks.

Shares of Fannie and Freddie have plunged in recent weeks due to fears that the two companies may need to turn to the Treasury Department to raise more capital.

Some even speculate that Fannie and Freddie may wind up being nationalized, which would cause the stocks to lose most, if not all, of their value.

This is a problem for several banks since they own a big chunk of the estimated $36 billion in preferred shares of Fannie (FNM, Fortune 500) and Freddie (FRE, Fortune 500).

Preferred shares typically offer higher dividend payments than common stock and holders of the preferred shares would, in theory, be paid before common shareholders in the event of a government bailout.

NEW YORK (CNNMoney.com) -- More homeowners than ever are selling at a loss, propelling the real estate market deeper into crisis.

In the 12 months that ended June 30, nearly 25% of all homes sold nationwide fetched less than sellers originally paid, according to real estate Web site Zillow.com.

While the nation's double-digit decline in home prices has been well documented, the new report underscores the economic force of those price declines. Homeowners are walking away with much less in their pocket when they sell. And that affects more than the real estate market.

"It's stunning what's happening out there," said Stan Humphries, Zillow's vice president of data and analytics, who looked at statistics that date back to 1996. "The numbers are the worst we've seen and it's not just the magnitude of the problem but the scope - so many markets are affected."