NEW YORK, Nov 27, 2007 (AFP) - US stock markets opened higher Tuesday following heavy falls a day earlier after banking giant Citigroup said it would receive a 7.5 billion dollar infusion from an Abu Dhabi investment fund.

The Dow Jones Industrial Average was up 56.65 points (0.44 percent) at 12,800.09 in initial trades as Wall Street opened for business.

The Nasdaq composite gained 20.45 points (0.80 percent) to 2,561.44 and the Standard & Poor's 500 broad-market index was up 6.51 points (0.46 percent) at 1,413.73.

Shares surged higher after Citigroup revealed late Monday that it had raised a multibillion-dollar injection from the Abu Dhabi Investment Authority which is controlled by the the largest emirate in the United Arab Emirates.

Citigroup's finances have been ravaged by the US housing slump. The bank warned earlier this month that it would probably have to write off between eight and 11 billion dollars largely due to soured mortgage investments.

Investors said they would be watching to see if Citigroup's announcement helps shore up the financial markets which have tumbled dramatically this month due to the lingering housing slump and a related credit crunch.

Fears about weakening economic growth have also weighed on Wall Street.