Twelve US cities, including Boulder, Colorado, and Providence, Rhode Island, are showing extended declines in housing values, reversing signs of a sustained recovery last year, according to Zillow.com.

The number of markets in a “double dip” jumped in January from five in December, data released today by Seattle-based Zillow show. The real estate information provider defines a double dip as five consecutive price drops after at least five straight monthly increases. The gains must be preceded by a period where values fell in at least 10 of 12 months.

The prospect of rising interest rates may be reducing home prices after the government boosted sales in 2009 with tax credits, increased federal housing agency lending and purchases of mortgage-backed securities by the Federal Reserve, said Stan Humphries, Zillow’s director of advanced analytics.

bloomberg.com