NEW YORK (AFP) - The tech-rich Nasdaq Composite Index led Wall Street sharply lower again Friday, closing out a dreary week at its lowest level in more than two months.

The Nasdaq sank 54.37 points (1.34 per cent) to 3,999.73, the lowest close since February 3, when the index settled for one session below the psychologically important 4,000 level.

The Dow Jones Industrial Average tumbled 140.32 (0.87 per cent) to 16,029.90, while the broad-based S&P 500 shed 17.28 (0.94 per cent) to 1,815.80.

US equities were in the red most of the day, but losses deepened in the last 90 minutes of trade.

Highflying technology stocks and biotechnology stocks are "driving an overall correction in the market," said Alan Skrainka, chief investment officer at Cornerstone Wealth Management.

"And how far that goes, and how fast, no one can know."