Existing-home sales tumbled in January, according to the National Association of Realtors, as buyers were likely waiting to see how details of the economic stimulus package would pan out. Existing-home sales – including single-family, townhomes, condominiums and co-ops – fell 5.3 percent month-over-month to a seasonally adjusted annual rate of 4.49 million units, compared to 4.74 million units in December and 4.91 million units in January 2008.