Pending U.S. home sales fell to a new low in March, an industry group reported Wednesday, signaling the housing slump has not reached its bottom even as the spring selling season begins. The National Association of Realtors (NAR) index of pending sales for existing homes fell to 83.0 from February's 83.8, the index's previous record low. The index stood at 103.9 in March 2007. A reading of 100 is equal to the average level of sales activity in 2001, when the index started. Falling home prices and a tight credit environment have hurt the housing market and caused potential home buyers to wait for better conditions. So far, there has been no evidence that the traditionally strong spring selling season is improving sales activity. NAR forecasts that existing home sales activity and the broader economy will improve in the second half of the year as larger home loans backed by the Federal Housing Administration become more widely available. NAR expects existing-home sales to rise slightly to an annual pace of 5.82 million in the fourth quarter from 4.95 million in the first quarter. For the year, the group estimates sales will total 5.39 million and then increase 6.1 percent in 2009 to 5.72 million. It also expects median home prices to decline 2.4 percent this year before gaining 4.1 percent next year.