U.S. economic activity declined in August for the second time in three months, the Conference Board said Thursday, suggesting that the economy continues to be weak. The Conference Board said its index of leading economic indicators dropped 0.1 percent last month after rising 0.5 percent in July and falling 0.5 percent in June. August weakness came from declines in manufacturing orders, consumer confidence, and average weekly manufacturing hours. According to Conference Board economist Ken Goldstein, the index depicts an economy still facing the significant domestic and international weakness, the AP reported.