Wednesday's stock market computer shutdown at the New York Stock Exchange was exaggerated in part by a very human problem.
As the market's complicated computer infrastructure went into meltdown, the exchange announced it would cancel any affected trades.
One problem: All of those electronic trades had to be nullified manually.
"At the NYSE this is a manual process," said Sal Arnuk, a principal at Themis Trading. "Is the NYSE technologically the most (robust) exchange in the world? No. The fact of the matter is the different exchange operators have diverse standards, different architecture. Some of them are more legacy than others. This is to be expected from time to time."