Typo, Glitches, Panic Blamed for Stock Market Mayhem

What's known in the business as a "fat finger" trade may have been responsible for yesterday's stock market chaos, analysts say. Multiple sources believe a trader at a major firm—possibly Citigroup—hit a "B" instead of an "M" while trading Procter & Gamble shares, selling a billion shares instead of a million, and sending the Dow Jones on a panicky rollercoaster ride. Major exchanges are also examining possible erroneous trades in multiple stocks that triggered glitches in the trading system, notes the Wall Street Journal.

Traders were already nervous and the Greek crisis had been sending prices downward even before the panic, the New York Times notes. The plunge "happened so quickly, it was like a torpedo," said a chief strategic officer at a top hedge fund. "It was mayhem." The lesson from yesterday's chaos should be that "any market can fail temporarily," writes Felix Salmon at Reuters, predicting that the panic that hit markets yesterday will result in "increased volatility and risk aversion." (More Wall Street stories.)