SAN FRANCISCO - JUNE 06: For sale signs stand in front of condominium complex June 6, 2007 in San Francisco, California. The National Association of Realtors announced today that it is lowering its forecast of the U.S. housing market as home sales continue to be weak. The NAR predicts that existing home sales will drop 4.6 percent to $6.18 million instead of 2.9 percent as previously forecast and new home sales are expected to slip 18.2 percent to 860,000 compared to the previous prediction of 17.8 percent. San Francisco has seen an 11 percent increase in inventory of properties listed for sale.