NEW YORK, Nov 19, 2007 (AFP) - US shares swung lower at the opening Monday as market caution was heightened by a jump in oil prices and a downgrade of US financial giant Citigroup, highlighting fears about the banking sector.

In the first trades, the Dow Jones Industrial Average fell 88.93 points (0.68 percent) to 13,087.86 and the Nasdaq composite shed 21.46 points (0.82 percent) to 2,615.78.

The broad market Standard & Poor's 500 index retreated 11.30 points (0.78 percent) to 1,447.44.

With no economic news on tap, the market focused on a rise in oil prices, with crude futures up 93 cents at 94.77 dollars a barrel in New York, and the latest analyst report on Citigroup.

Goldman Sachs said in a note that Citi may have to write off an additional 15 billion dollars in soured mortgage investments, adding to the gloom in the finance sector.

"There is a slight bearish lean to the news this morning, but this as much as anything reflects the cautious tone," said Dick Green at Briefing.com.

Green said the market will focus on holiday retail sales, which are a key factor for the US economy.

"Almost every year recently, the talk and preliminary indications have been poor, only to ultimately have spending come in close to or above expectations," he said.