NEW YORK — Stocks moved to the threshold of a bear market Friday, triggering debate on Wall Street on how long a downturn could last and how much damage it could wreak.
A day after losing 358.41 points, the Dow Jones industrial average shed an additional 106.91 points, or 0.9%, to close out a dismal week at 11,346.51.
The blue-chip indicator is now down 19.9% from its high last October -- a tick away from the 20% decline that is the widely held definition of a bear market.
"It looks and feels like a bear market," said Howard Silverblatt, senior index analyst at Standard & Poor's Corp. in New York.
Wall Street has weathered five of these downturns since 1973. The most recent one followed the bursting of the tech bubble and lasted from March 24, 2000, to Oct. 9, 2002.
During that period, the Standard & Poor's 500 index of blue-chip companies tumbled 49.1%.
How far the market will fall this time, and for how long, is anyone's guess. But stock market analysts point out that all the major signs of trouble appear to be in place, including a widespread weakening of stocks across market sectors and a lack of enthusiasm, even on up days.
And rallies, such as the one from March to May, end with vicious spasms of selling.
"We're nowhere near the bottom," said Tony Kolton, chief executive of MarketHistory.com. "We've got a long way to go."
Friday's downturn came as crude oil closed above $140 a barrel for the first time, finishing up 57 cents at $140.21.
Financial stocks were weak again on concerns that banks and brokerages would report a spate of sizable mortgage-related write-offs during the next few weeks.
Throughout the downturn, bulls have contended that the market could soar at the first hint of an economic turnaround, such as a retreat in oil prices or good news from a beleaguered investment bank. They've contended that investors have plenty of money on the sidelines that would become fresh powder once fears of a recession subside.
Such talk has stirred investor optimism and has helped explain why the major averages haven't already fallen 20% or more.
But the daily trading patterns of stocks themselves paints a more ominous picture, experts say.
Rather than setting the foundation for a sustainable recovery, trading patterns indicate that a bear market is underway even though the losses haven't met the textbook definition.
For example, the percentage of stocks trading above their 200-day moving average -- a basic measure of strength -- has steadily weakened since last year, said Phil Roth, a technical analyst at Miller Tabak & Co. in New York.
In February 2007, 84% of stocks were above their 200-day line.
That fell to 53% last October and to 42% during the rally that ended last month. Thus, even though the major averages rose from March to May, most stocks did not, Roth said.
Only 27% of stocks are currently above that mark, Roth said.
Another classic sign of a bear market is when trading volume is heavier in declining stocks than in advancing ones. That indicates sellers are more anxious to get out of the market than buyers are to get in.
That's the case now, said Paul Desmond, president of Lowry Research Corp., a stock-research firm in North Palm Beach, Fla.
There's been "a continual withdrawal of buying interest," Desmond said.
Bear markets vary in duration, with some lasting just a few months and others stretching more than two years. The current downturn appears to be of the drawn-out variety, Desmond said.
Though the major averages officially peaked last October, the market essentially topped last July, many market watchers say.
A hallmark of lengthy bear markets is interim rallies that start promisingly but eventually fizzle, such as the one that petered out last month, Desmond said.
Investors try to jump in at the lows but get burned when stocks keep cratering. Their selling then prolongs the downturn and deprives the market of buying power later on because they're hesitant to step back in.
Desmond's advice to investors is to be patient and be willing to sit on the sidelines until the market is in a clear uptrend.
"You see so many situations of people jumping the gun and saying, 'Are we there yet?' " Desmond said. "They want to see a bottom. We haven't even met the standard definition of a bear market yet, much less met the average decline. And investors need to at least be prepared that this could be an extended decline."
In other market highlights:
Among other major indexes, the Standard & Poor's 500 fell 4.77 points, or 0.4%, to 1,278.38. It's 18.3% off its peak. The Nasdaq composite index declined 5.74 points, or 0.3%, to 2,315.63. It has tumbled 19% from its high.
The finance sector suffered broad losses. Bank of America declined 22 cents to $24.59 and Wachovia slipped 70 cents to $16.22. On Wall Street, Goldman Sachs dropped $1.70 to $174.56 and JP Morgan Chase retreated $1.27 to $35.05.
Some oil companies were helped by rising crude prices. Exxon Mobil gained 14 cents to $86.55. Chevron added 39 cents to $97.80.
Among tech issues, Google lost 75 cents to $528.07 and IBM fell $1.08 to $120.05. Apple added $1.83 to $170.09.
Big Three automaker Ford fell below $5, dropping 9 cents to $4.98.
The yield on the 10-year U.S. Treasury note fell to 3.97%, from 4.04% on Thursday.