Stock futures slid and oil prices surged above $100 a barrel on Thursday as Iran continued its assaults on U.S. Gulf allies and tankers in the Persian Gulf, with a massive release of oil supplies by the International Energy Agency doing little to calm jittery investors. "Iran's strategy of sowing economic chaos in the Gulf is working as tankers come under attack and Hormuz stays shuttered, pushing Brent up toward $100," Wall Street analyst Adam Crisafulli, head of Vital Knowledge, said in a