It is bot trading (robot or computer trading, sometimes also...

It is bot trading (robot or computer trading, sometimes also intertwined/combined with HFT (high frequency trading), and also called algorithmic trading), it is a pretty big subject for me to explain all the ins and outs here, try googling some of those terms, or even search some of these terms on Hot Copper, using the advanced search function, and see what you get. Some people get very upset about bot trading, as it can be used detrimentally, but it can also be used in a positive manner as well, although the real unfairness (when compared to the retail market), IMO, is that each trade can be less than $500 for them (it can be 1 cent if they choose)......... if the playing field was leveled here, it would not be anyway near as bad.

cheers