It appears this article was written and slated for a September publication before the Knight incident. While the Knight incident is mentioned in the leading editor's note, the crash most prominently dicussed in the article is the May 2010 'flash crash'. The title as submitted is vague and misleading.
I remember that. I was working in HFT at the time, so I certainly noticed when it happened.
But I decided to try an exercise. I went to google finance and graphed the S&P. From the graph (weekly data points) I can't tell when the flash crash occurred.
It's almost as if the flash "crash" was just a flash in the pan...
