U.S. stocks slid on Friday as investors worried the economy's recovery might not be sustainable and financials sank as an influential bank analyst projected a $10 billion write-down for Citigroup.

Investors unloaded shares across the board. Wall Street's favorite measure of investor fear, the CBOE Volatility Index <.VIX> vaulted to 31.25 -- its highest level since July.

Citigroup fell more than 5 percent to $4.08 after CNBC reported that Calyon's bank analyst Mike Mayo is forecasting the U.S. bank will write down $10 billion in deferred tax assets in the fourth quarter.

The KBW bank index <.BKX> fell 4.8 percent, while the S&P financial index <.GSPF> lost 4.5 percent. Other sectors taking a beating were technology, industrials and materials.

The market's slide, coinciding with technical glitches on the New York Stock Exchange, wiped out Thursday's gains, which represented the best one-day rally for stocks in three months.

Analysts said there were doubts that the recovery would be strong enough to justify higher stock prices.

Financials have been and continue to be the lightning rod for the stock market, said Ted Weisberg, trader with Seaport Securities in New York. There are political and fundamental issues that make that sector vulnerable to weakness and that weakness will spread throughout the rest of the market.

The Dow Jones industrial average <.DJI> slid 235.79 points, or 2.37 percent, to 9,726.79. The Standard & Poor's 500 Index <.SPX> dropped 27.71 points, or 2.60 percent, to 1,038.40. The Nasdaq Composite Index <.IXIC> tumbled 50.01 points, or 2.38 percent, to 2,047.54.

A huge influx of orders prevented the New York Stock Exchange from disseminating quotes shortly after the start of trading on Friday.

NYSE Euronext , the parent of the New York Stock Exchange, said the delays followed an inordinate influx of orders received as Friday's session got under way. Later in the session, the company had to temporarily transfer quote processing to a backup system.

The interruption on the NYSE and in the NYSE Amex cash equities trading was later resolved.

The benchmark S&P 500 is up 53.7 percent from the 12-year closing low of March 9. It has shed 5.3 percent from its post-March peak it reached on October 19.

(Reporting by Ellis Mnyandu; Additional reporting by Leah Schnurr; Editing by Jan Paschal )

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