[mmodahl]

The book picks up in the middle of the story after the first step in electronic trading has started, but before all participants are on a level playing field.

Human market makers at those exchanges are entering their quotes(by hand even). And Brad Katsuyama uses new electronic technology to crush them. Taking their entire inventories and moving the markets against them.

The human market makers fight back and make their computers do the market making for them and Brad is hurt because his technology is no longer the best way to trade.