U.S. stocks accelerated their losses on Friday with the S&P 500 down 3 percent as investors worried the economy's recovery might not be sustainable and shares of financials tumbled.

* Financials were hurt as an influential bank analyst projected a $10 billion write-down for Citigroup , which fell more than 6 percent.

* The Dow Jones industrial average <.DJI> fell 258.99 points, or 2.60 percent, to 9,703.59. The Standard & Poor's 500 Index <.SPX> tumbled 31.44 points, or 2.95 percent, to 1,034.67. The Nasdaq Composite Index <.IXIC> gave up 53.46 points, or 2.55 percent, at 2,044.09.

(Reporting by Leah Schnurr; Editing by Kenneth Barry)