House prices fell 3.5 percent in January, according to an index released Tuesday by Integrated Asset Services LLC, a provider of default management and residential collateral valuation. The most recent IAS360 House Price Index found that home prices posted their worst single-month decline from December 2008 to January 2009 since the index's peak in November 2006. “These are unprecedented times to say the least,” said Dave McCarthy, President and CEO of Integrated Asset Services. “We’re seeing house prices plummet at a rapid pace throughout the country. We’ll be keeping a close eye on the data for signs of a bottoming out.” The decline seen in January represented some $610 billion in lost housing stock value, bringing the total value lost since "the start of the economic meltdown last September" to approximately $2.4 trillion. The national price index has fallen almost 25 percent from its peak in November 2006, according to IAS. House prices had posted a 13.8 percent decline overall in 2008 since 2007, the company reported in February. The IAS360 tracks home sales down to the neighborhood level, and then rolls up local totals in 360 counties, nine census divisions, four regions, and the nation overall. Counties in California and Florida overall have been hit hardest, IAS said, with six Californian counties and four Floridian counties posting declines of more than 41 percent from their peaks. The San Joaquin county in California has posted a 59.9 percent decline from its May 2006 peak, while the Pasco county in Florida posted a 57.3 percent decline from its July 2006 peak. Wealthy counties are not exempt from sweeping declines, IAS reported. Three Virginian counties -- Loudon, Stafford and Prince William -- have posted declines of more than 30 percent since their respective peaks in 2006. Two of the wealthiest counties posted month-over-month inclines since December. Douglas, Colo. saw house prices creep up 2.1 percent in January, when they held at 0.6 percent above the year-ago level. The Putnam, N.Y. county saw a 1.1 percent month-over-month increase in house prices, which are at a surprising 3.4 percent above the year-ago level. Visit or further details on the index. Write to Diana Golobay at