NEW YORK - The Nasdaq Composite Index <.IXIC> confirmed on Friday it is in a bear market for the first time since 2008, underscoring fears that the longest bull run in history for U.S. stocks could soon be over.

The index finished the day down 21.9 percent from its Aug. 29 record closing high, exceeding the 20 percent decline considered the threshold for a bearmarket.

The Nasdaq is the first of the three major U.S. stock indexes to cross that threshold, with its drop in less than four months the latest sign that the bullmarket that began during the financial crisis a decade ago could be almost done.

Several other key indexes in recent days have confirmed they were in bear markets, among which are the Russell 2000 small-cap index <.RUT> and the Dow Jones transportation average <.DJT>.

The S&P 500 <.SPX>, the benchmark for U.S. stocks, is not yet in a bear market, though more than 60 percent of its components are.

The S&P 500 is down 17.5 percent from its Sept. 20 record high close, while the Dow Jones Industrial Average <.DJI> is down 16.3 percent from its Oct. 3 record.

The Nasdaq's fall reflects a sharp move by investors away from what had been the market's leaders - the so-called FAANG group of five favourite technology and internet stocks.

"It's the old saying, the generals finally got hit," said Quincy Krosby, chief market strategist at Prudential Financial in Newark, New Jersey.