A closely watched measure of future U.S. economic activity fell slightly in April after six consecutive months of increases, a private research organization reported Thursday, signaling continued modest economic growth. The Conference Board said its index of leading economic indicators declined 0.1 percent in April from the previous month to 95.5. The March reading had been the highest level since mid-2008. However, before the 2007-2009 recession began, the index routinely topped 100. The index, designed to predict activity three to six months in the future, fell in April because of weakness in housing and hiring. Conference Board chief economist Ken Goldstein said last month's drop reflected an economy that is still struggling to gain momentum.