Stock losses speed up

NEW YORK (CNNMoney.com) -- Stock losses accelerated Monday morning as worries about the banking sector and another spike in oil prices gave investors a reason to bail out of equities.

The Dow Jones industrial average (Charts) lost over 1 percent over an hour into the session. The S&P 500 (Charts) index lost 1.2 percent. The Nasdaq composite (Charts) declined 1 percent.

Small cap stocks were hit harder with the Russell 2000 (Charts) falling 2.1 percent.

Goldman Sachs downgraded Citigroup (Charts, Fortune 500) to "sell" from "neutral" Monday and said the bank will likely have to take $15 billion in writedowns over the next two quarters due to bets on risky debt. Citigroup shares fell 3.3 percent.

Goldman also cut its price target on Merrill Lynch (Charts, Fortune 500), Morgan Stanley (Charts, Fortune 500) and others in the sector, AP reported.

Among other stock movers, Lowe's (Charts, Fortune 500) slipped after posting lower quarterly earnings that topped estimates and warning that its fourth-quarter earnings won't meet estimates.

In merger news, Celgene (Charts) said it will buy Pharmion (Charts) for around $2.9 billion in cash and stock.

Market breadth was negative. On the New York Stock Exchange, losers topped winners five to one on volume of 390 million shares. On the Nasdaq, decliners topped advancers by more than three to one on volume of 540 million shares.

Oil prices reversed course, giving up early gains. U.S. light crude oil for January delivery fell 49 cents to $93.35 a barrel on the New York Mercantile Exchange.

Treasury prices rose, lowering the yield on the 10-year note to 4.14 percent from 4.16 percent late Friday. Treasury prices and yields move in opposite directions.

In currency trading, the dollar rebounded a bit against the euro and declined further versus the yen.

COMEX gold for December delivery fell $7.20 to $779.80 an ounce.