From a report at the link below:
In one of the most dizzying half-hours in stock market history, the Dow plunged nearly 1,000 points before paring those losses—all apparently due to a trader error.
According to multiple sources, a trader entered a "b" for billion instead of an "m" for million in a trade possibly involving Procter & Gamble a component in the Dow.
CNBC's Jim Cramer noted suspicious price movement in P&G stock on air during the height of the market selloff.
Sources tell CNBC the erroneous trade may have been made at Citigroup.
Link
