The number of U.S. initial claims for unemployment insurance fell by 21,000, or 3.8%, in the week ended Sept. 19 from the previous week's revised number of 551,000, the U.S. Department of Labor reported today.

The four-week moving average of claims fell by 11,000, or 2.0%, to 553,500 from the previous week's revised average of 564,500.