That question may be the key to the future actions of the Federal Reserve. One estimate of "How Low Will Housing Go?" comes from Jan Hatzius, Chief Economist of Goldman Sachs:
"Our working assumption has been that US home prices are about 15% overvalued. This relies on a simple "affordability" measure which essentially adjusts the home price/income ratio by the level of (nominal) mortgage rates. Depending on one’s assumption about income growth, the likelihood of overshooting on the downside, and the length of the adjustment process, this suggests cumulative nominal home price declines of 5-15% in the next few years.
However, affordability is becoming an increasingly problematic concept because it ignores changes in credit availability and changes in nonconforming mortgage rates. Hence, it may be better to look at simpler price/income or price/rent ratios to get a sense of house price valuation. These paint a more dire picture.
Even if we assume that the long-term trend for price/income and price/rent is higher now than the average of the 1975-2000 period (because interest rates are likely to stay lower), cumulative nominal price declines of 15%-30% are possible."
That’s not so different from what HSBC HomePulse wrote back in January 2006:
"We suggest that about half of the US housing market is frothy and that this ‘bubble zone’ may be overvalued by as much as 35-40%, after taking into account low interest rates and tax advantages.
Current valuations imply a large permanent reduction in the risk premium and/or a sizable step up in future capital gains, not all of which, we think, is justified. The ‘bubble zone’ accounts for 50% of US GDP, or over USD, nearly the size of the German, French, and UK economies put together. In other words, it’s big. Therefore, when these housing bubbles begin to deflate, it is likely to have substantial macroeconomic consequences.
What’s troubling is that even a perfect ‘soft landing’ in the form of flat national house prices would be consistent with a 35-40% collapse in existing home sales. The gush of liquidity from mortgage equity withdrawal would dry up, resulting in a growth drag worth over 3% of GDP. If this adjustment can be managed over many years (and hopefully it will), the economy can avoid recession and get away with soft growth.
If the process is squeezed into a shorter time frame instead, then recession is probable, forcing the Fed to once again consider unconventional policy options – a probability that would only rise if the money supply were to decline at the same time the ‘bubble zone’ deflates."
Whenever I hear anyone suggest that these events were totally unforeseeable, I know that person is full of $%#*.
A Froth-Finding Mission: Detecting US housing bubbles
HSBC Macro US Economics, January 2006