By Ellis Mnyandu

Citigroup , down more than 15 percent to $4.98, was a standout drag on the financial sector, while shares of JPMorgan and Bank of America fell 5 percent and 3.5 percent respectively.

The fall in Citigroup, a Dow component, followed a deal by the embattled bank to sell a controlling stake in its crown jewel unit, the Smith Barney retail brokerage, to Morgan Stanley for $2.7 billion.

Analysts reckon the Smith Barney sale was a precursor to a break-up of Citigroup and that the bank must be urgently seeking to replenish capital due to mounting losses.

"You'd think the news on banks is baked in, but there's still a lot of headwinds," said Rich Parker, head of trading, Stanford Group, in New York.

"The write-downs are starting to really scare people outside of the banking area as well. Is there a balance sheet out there that you can really trust? By all indications, it seems the recession is going to be a historically long one."

The Dow Jones industrial average <.DJI> slid 277.01 points, or 3.28 percent, to 8,171.55. The Standard & Poor's 500 Index <.SPX> tumbled 29.99 points, or 3.44 percent, to 841.80. The Nasdaq Composite Index <.IXIC> dropped 48.07 points, or 3.11 percent, to 1,498.39.

The sell-off marked another hindrance to the market's push to recover from its November bear market low. The benchmark S&P 500 began 2009 up more than 20 percent from that low but is now up about 11.5 percent. The S&P financial index <.GSPF> fell nearly 6 percent.

Sales at U.S. retailers fell 2.7 percent in December, government data showed on Wednesday, as a deteriorating economic climate forced consumers to cut back on spending during the key holiday period.

Consumer spending accounts for about two-thirds of U.S. economic activity and as such is a key pillar of corporate profits. The S&P retail index <.RLX> declined 3.7 percent.

Investors also sold off shares of economic bellwethers including big manufacturer Caterpillar Inc , down 6 percent. On Nasdaq, shares of iPhone maker Apple Inc led the slide, falling 2.4 percent to $85.64.

Even more unnerving to investors was a forecast by Morgan Stanley analysts that HSBC , Europe's biggest bank, is likely to halve its dividend and may need to raise up to $30 billion of capital.

Additionally, Germany's Deutsche Bank posted a loss of about $6.4 billion for the last three months of 2008, hitting markets in Europe.

JPMorgan is due to post quarterly results on Thursday after it moved up its reporting date, followed by Citigroup on Friday after it also moved up its results date.

Thomson Reuters data show expectations for JPMorgan have crumbled: A month ago it was expected to earn 27 cents per share in the fourth quarter. Two days ago that view was down to 5 cents. Before the bell, the view was a penny before special items.

On Tuesday, Federal Reserve Chairman Ben Bernanke said more steps were needed to stabilize banks, reviving the idea of authorities sopping up toxic assets from banks' books.

(Editing by James Dalgleish)