Investors have fled Wall Street as fear grows about the stability of the largest U.S. banks and worries mount about General Motors Corp. Stocks are ending at 12-year lows, more than wiping out a one-day rally. Investors are contending with more disheartening economic readings, new concerns about the stability of GM and ongoing uncertainty about the financial system. According to preliminary calculations, the Dow Jones industrial average is down 281 points at 6,594. The S&P 500 is down 30 at 682, while the Nasdaq composite index is down 54 at 1,299. About 10 stocks fell for every one that rose on the New York Stock Exchange. Volume was a heavy 1.8 billion shares.