New York ? UAL’s bankruptcy filing and a brokerage downgrade of IBM put investors in a black mood Monday, sending stocks sharply lower and the Dow Jones industrials down more than 170 points.

Analysts said many investors were tempted to sell after the market’s recent two-month rally, while others were nervous about the United Nations’ search for weapons of mass destruction in Iraq.

“The market is still in a malaise,” said Charles Pradilla, chief investment strategist at SG Cowen Securities. “You inject the recent news into a market still in the process of taking profits, and you get this real choppy action.”

The Dow slid 172.36, or 2 percent, to close at 8,473.41, having fallen 2.8 percent last week to snap an eight-week winning streak. Blue-chip stocks have now declined in the last six of seven sessions to a level not seen since Nov. 13.

The Nasdaq composite index declined 55.30, or 3.9 percent, to 1,367.14, also the lowest since Nov. 13. The Standard & Poor’s 500 index dropped 20.23, or 2.2 percent, to 892.00.