On the other, it has opened the possibility of nightmare events like flash crash of May 2010, when in 5 minutes the DJIA recorded its biggest intraday fall of about 1000 points (9%), to recover most of the losses 20 minutes later.
In August 2012, runaway trading by Knight Capital affected the shares of 148 companies and Knight Capital itself had to take a loss of USD 440 million in what has been attributed to “technology breakdown”.