So, wouldn't this constitute a major transfer of wealth from individual investors with stop-loss orders to institutional investors like Goldman Sachs et al whose computers detected the dip and bought the stock back up?
(...) on December 8, 2005 in which a Mizuho dealer mistakenly sold 610,000 shares in J-Com, a recruitment business, at 1 yen instead of selling 1 share at 610,000 yen.
The dealer, understood to be a 24-year old woman, immediately realised the mistake but was unable to cancel the trade because of a technical glitch in the exchange's trading system. Mizuho was forced to buy back the shares, leaving it with a 40.7 billion yen loss, prompting the firm to cancel year-end bonuses for all staff in the trading unit.
Note in Japan executed trades cannot be canceled (though in this case the trader was supposed to be able to cancel the orders before they were executed). Many brokers made a big profit. Some institutional investors too. One particular day trader became quite rich and to this day is a sort of legend on internet trading boards.