Semiconductor companies' shares fell after a trade group announced that sales had fallen.

The Semiconductor Industry Association reported that sales in February fell 6.5 percent to $20.09 billion from $21.48 billion in January. It described the fall as a typical seasonal weakness, although noted that there were declining prices and fewer unit shipments.

Sales were slightly up by 4.2 percent from $19.28 billion in February 2006, but this was much lower than sales levels in December.

AMD, Intel, Micron Technology, NSC shares fell on the back of news.