Sign of the times...
The damage was exacerbated by the growing use on Wall Street of automated programs that trigger stock trades without any human interaction. The so-called algorithmic trading mechanisms, which buy and sell stocks based on news headlines and earnings data, were responsible for roughly a quarter of New York Stock Exchange trades in the last week of August.
Investors said simple human scrutiny would have indicated the UAL story was old, but computerized trading systems don't make such determinations.
"A trader can pull back before proceeding, but some of these less sophisticated [automated trading systems] can't do that," said Bernie McSherry, a senior vice president with New York institutional brokerage Cuttone & Co.