U.S. stocks added to Friday gains as the unemployment rate in the world's biggest economy fell unexpectedly to 7.8% in September, down from 8.1% in the previous month. The Dow Jones Industrial Average surged 0.5%, to 13,636.54; the Standard & Poor 500 Index added 0.4%, to 1,467.78, while Nasdaq 100 futures jumped 0.3%, to 3,159.32.