A truly awful day on Wall Street erased any memory of yesterday’s rally, as indexes across the board dropped 4 percent. The Dow Jones Industrial Average slid 281.40 points, or 4.09 percent, to close at 6,594.44—its lowest since April 15, 1997—while the S&P 500 lost 4.25 percent and the Nasdaq 4 percent. Banks led the race to the bottom, with Citigroup dipping below $1 a share for the first time ever before closing at $1.02, and Moody’s put out a warning on Wells Fargo and JPMorgan Chase. “The banks are a disaster,” one trader told The Wall Street Journal. GM also fell under $2 a share after auditors warned of a possible bankruptcy.