US STOCKS-Wall St falls on sovereign fears, rebound possible
April 18, 2011 at 16:25 PM EDT
* S&P revises U.S. outlook to 'negative' * Materials, oil fall after China's move to curb liquidity * Greece denies it is seeking debt-restructuring plan * Dow off 1.1 pct, S&P down 1.1 pct, Nasdaq off 1.1 pct
