World shares and U.S. futures have fallen after big technology shares that have thrived during the pandemic staged a comeback overnight. Hopes raised by news of potentially effective vaccines for COVID-19 have been countered by concerns over the logistical challenges of delivering the shots as meanwhile new cases of the virus surge in many countries. Shares declined Thursday in Paris, Frankfurt and Hong Kong but rose in Tokyo. Overnight, the S&P500 and Nasdaq composite pushed higher while the Dow Jones Industrial Average edged lower. Markets have been riding a wave of relief over the end to the U.S. presidential election and hopes for a potential vaccine to beat back the pandemic.