Record Numbers, page-34

To anyone interested in why the SP tumbled so hard today, just need to dig deep into the intraday chart and see that a tiny gap down to 135.5 "needed" to be filled by an algo. This was followed by some hard and fast bouncing back up the charts on good volume (a good sign). There is still a small gap back to 137.0 that may "need" filling tomorrow, but I don't give much heed to intraday gaps on 5-minute charts.



Anyways, if you don't understand how algorithms and High-Frequency trading (HFT) work, I would suggest some study with Michael Lewis' Flash Boys: A Wall Street Revolt. Explains quite a bit of the intricacies of modern day trading and should be required reading for those trading stocks on very short timelines in order to avoid being shaken out by moves like this.