Market Rally in Peril as Iran Cease-Fire Unravels. Stock Futures Dive, Oil Prices Soar.

Stocks looked set to tumble and oil prices were rallying on Monday as a flare-up in tensions between the U.S. and Iran raised uncertainty about a looming second round of talks to end the war in the Middle East. S&P 500 and Nasdaq 100 futures were 0.5% lower. President Donald Trump said on Sunday that the U.S. intercepted an Iranian-flagged cargo ship trying to get past its blockade of the Strait of Hormuz.