The Dow Jones Industrial Average fell 0.3 percent, the broad S&P 500 index fell 0.6 percent and the tech-heavy Nasdaq Composite fell 0.9 percent.
One of the big losers was software company Adobe, which, after Thursday's 13.7 percent drop, lost another 7.6 percent. The reason was a weak sales forecast.
After falling slightly during the day, oil prices rose again. Markets are having difficulty seeing clear signs that the war by Israel and the U.S. against Iran is in its final stages.
For the week as a whole, the Dow lost 1.2 percent, the S&P 500 fell 1.6 percent and the Nasdaq Composite fell 1.3 percent.
The Dow fell for the third week in a row, the first such long decline in about a year.
