By Kate Gibson

U.S. stocks fell Monday, with the Dow Jones Industrial Average extending its losing streak into a fourth straight session, with investors leery ahead of Alcoa Inc.'s results in what could mark the unofficial start of a particularly grim earnings season.

Energy, financials and materials led the broad market declines.

The Dow Jones Industrial Average (DJI) fell 87.77 points to 8,511.44, with 23 of its 30 components trading lower.

Weighing the most on the blue-chip index, Citigroup Inc. (C) shares fell 12% with the banking powerhouse reportedly near a deal to combine its brokerage business with Morgan Stanley (MS). Shares of Morgan Stanley (MS) led all S&P 500 financial stock gainers, climbing 1.2%.

Another Dow laggard, Alcoa (AA) shares declined 6.9% after its downgrade by Deutsche Bank to a sell from a hold in the wake of last week's announced cuts in production and employees by the aluminum giant.

Alcoa reports its earnings after the market closes, with analysts expecting the company to report a loss of 10 cents a share.

Intel Corp.(INTC) reports its results on Thursday, with the chip maker and Wal-Mart Stores Inc. (WMT) among the companies offering bleak forecasts last week.

Shares of technology company Palm Inc. (PALM) gained 4.5% after its upgrade to hold by Citibank. .

The S&P 500 (SPX) fell 15.43 points to 874.92, and the Nasdaq Composite (RIXF) declined 26.15 points to 1,545.44.

Volume on the New York Stock Exchange topped 578 million, and decliners outpaced advancers more than 2 to 1. On the Nasdaq, 350 million shares traded, and decliners routed advancers almost 2 to 1.

Oil futures tumbled 6% below $40 a barrel as the global economic downturn continued to fuel worries about demand. Crude for February delivery were most recently off $2.93 to $37.94 a barrel on the New York Mercantile Exchange. .

Gold futures fell to near one-month lows, pacing sharp losses in crude oil and other commodities. Gold for February delivery was last down $33.1 at $821.9 an ounce.

Overseas, stocks in Europe declined for a fourth straight session, as worries over the global economy sent oil-sector companies lower. .

Asian shares also fell amid weakness among steelmakers and miners.

On Friday, stocks fell for a third consecutive day after the government reported the nation's unemployment rate climbed to 7.2% in December from 6.8% the prior month.

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