From the San Francisco Association of Realtors:

Scarcity of Defaults Demonstrates Enduring Value of San Francisco Real Estate

Of all U.S. mortgage holders, about one quarter, or 11.3 million households, is underwater, meaning they owe more than their homes are worth. In California, the percentage is even greater—35 percent.

According to First American CoreLogic, the tipping point appears to come when a home owner has a negative equity of 25 percent or more. At that point, many owners choose to cut their losses and voluntarily walk away from their homes. To prevent this result and to avoid a costly and time-consuming foreclosure, banks typically encourage owners to market their property as a short sale.

So, how does San Francisco and the northern peninsula stack up against the rest of the country, and the State as a whole? These areas are doing much better. The percentage of home owners underwater in the San Francisco-San Mateo-Redwood City area is only 10.4 percent. And the percentage of home owners underwater by 25 percent or more is only 2.6 percent.

Real estate sales in San Francisco and the northern peninsula may be lagging previous years but real estate values have remained strong through one of the worst economic downturns since the Great Depression—a fact of which homeowners and prospective buyers should be reminded from time to time.