Stocks finished near session lows in choppy trading Wednesday, with the Dow and S&P wiping out all of the previous session's gains led by financials, as investors continued to cautiously monitor developments in the European banks. The Dow Jones Industrial Average finished down over 500 points, wiping out the previous session's 429-point rally. The blue-chip index has had triple-digit moves in four of the last five trading days. The S&P 500 and Nasdaq also finished sharply lower. The CBOE Volatility Index, widely considered the best gauge of fear in the market, soared more than 25 percent.