The broad S&P 500 index closed up 0.1 percent, the Dow Jones Industrial Average closed down 0.1 percent, and the tech-heavy Nasdaq Composite closed up 0.2 percent.
The oil price increases followed President Donald Trump's announcement on the night of Maundy Thursday that Iran would be bombed "back to the Stone Age."
U.S. WTI oil has risen 11.5 percent during the day, now trading at $111.60 per barrel. North Sea oil has risen 7.5 percent to $108.60 per barrel.
