A lot of the insto's run algo execution systems instead of placing the order with a dealer.
The algo system then "manages' the order into the market.
The overwhelming "strategy" is a simple VWAP execution. Ie Complete my order and beat the VWAP for the day (or from order placement time). The execution system will do this by splitting up the order into multiple trades over the course of the day. They dont have to pay brokerage on each trade.
