Shares of energy companies rose sharply alongside oil futures.
Oil surged by more than 3% in New York after Iran attacked a vessel near Qatar, likely slowing oil shipments through the Strait of Hormuz once again.
Hopes that Middle East exports could return to prewar levels have been dented in recent sessions by an escalation in Houthi attacks on Saudi Arabia and Iran's renewed focus on blockading Hormuz shipping lanes.
Major U.S. oil drillers were shutting in production on the Gulf of Mexico and evacuating workers as Hurricane Isaias bore down on the U.S. coast.