The slumping housing market cannot find a floor: It is now burrowing into a previously unknown subbasement.

Economic data show how sick the market is. Sales of existing homes tumbled 8.6 percent in November, to an annual rate of 4.5 million homes, according to the National Association of Realtors. It was a steeper fall than expected and the sharpest decline on record.

The median sales price of a home fell 13.2 percent over the last 12 months, to $181,300. That is the biggest price decline since the trade group began collecting data in 1968.

Sales of new homes sank 2.9 percent in November, to an annual rate of 407,000, the Commerce Department said. It was also a weaker report than expected. The median price of a new home fell 11.5 percent, to $220,400 in November.

Foreclosures are swelling a glut of homes on the market. Despite new lows in mortgage interest rates, the weak economy and fears about the job market are limiting any buying. The N.A.R. report says that there is now 11.2 months' worth of homes on the market.

The oversupply and the slide in prices means that we have a long way to go before the market adjusts. Falling prices mean that millions more homes will be worth less than the value of the mortgages on them. These homeowners will have to decide whether to continue, in essence, throwing money away to keep to their contract. Others will have lost their jobs and can no longer afford their mortgages. Even more houses will come on the market as result.