Worries about the war with Iran sent oil prices back to $100 per barrel and stocks sinking worldwide.

The S&P 500 fell 1.5% Thursday and returned to big swings following a couple days of relative calm. The Dow Jones Industrial Average dropped 1.6%, and the Nasdaq composite sank 1.8%.

The center of action was again the oil market, where the price of a barrel of Brent crude got as high as $101.59. Treasury yields climbed in the bond market on worries about higher inflation and fewer cuts to interest rates by the Federal Reserve.

On Thursday:

The S&P 500 fell 103.18 points, or 1.5%, to 6,672.62.

The Dow Jones Industrial Average fell 739.42 points, or 1.6%, to 46,677.85.

The Nasdaq composite fell 404.16 points, or 1.8%, to 22,311.98.

The Russell 2000 index of smaller companies fell 53.91 points, or 2.1% to 2,488.99.

For the week:

The S&P 500 is down 67.40 points, or 1%.

The Dow is down 823.70 points, or 1.7%.

The Nasdaq is down 75.70 points, or 0.3%.

The Russell 2000 is down 36.31 points, or 1.4%.

For the year:

The S&P 500 is down 172.88 points, or 2.5%.

The Dow is down 1,385.44 points, or 2.9%.

The Nasdaq is down 930.01 points, or 4%.

The Russell 2000 is up 7.08 points, or 0.3%.