Just to break the tedium a bitI have been doing some digging...

Just to break the tedium a bit

I have been doing some digging into bot's and have come up with some answers.

Basically some trade on technical rules - buy on one side of the bollinger bands sell at the other for example.

A big use though seems to be VWAP (Volume Weighted Average Price) trading which as it turns out is in fact intended to not manipulate the price. This came as a bit of a surprise. The argument is that you have a big parcel to sell or buy and you do not want your order to push the price around. So you have a program that breaks the order down into pieces and sells each piece at the days VWAP.



If you are curious do some googling on VWAP trading and algorithmic trading.

http://en.wikipedia.org/wiki/Algorithmic_trading

http://en.wikipedia.org/wiki/VWAP