That great sucking sound you may be hearing is the sound of the US economy and Wall Street tumbling further into the black hole known as the housing slump.

News of the accelerating slide in US housing prices is contained in the latest Standard & Poor’s/Case Schiller index.

The index of single-family shows house prices contracted by 13.6% year-on-year in February, the biggest since records began in 1987. That compares to an annual rate for the 10 city index of 11.4% in January.

The broader 20-city index fell 12.7% compared with the year to February, 2007, the biggest drop since the index’s inception in 2001. This index was falling at an annual rate of 10.7% in January, so there has been a significant acceleration in price falls.

It shows that despite confidence that the worst is over with the credit crunch and high expectations for a rebound in the economy later this year; the depression in the American housing market is intensifying, not easing.

It’s no longer a subprime problem, analysts at Barclays investment bank reckon around $US800 billion of debt linked to subprime and higher quality so-called Alt-A mortgages could become problematic this year, putting further pressure on housing prices and mortgage values.

In fact US house prices have now fallen by more over the past year than the US stockmarket: the Standard & Poor’s 500, the major index is off around 8% since its peak late last year. US economists say house prices are now falling faster than anyone had previously thought possible and are acting like equity prices in the speed of the decline.