Predatory algorithmic trading
Wonky PDF. Here's one of the effects:
High frequency trading strategies have become a stealth tax on retail and institutional investors. While stock prices will probably go where they would have gone anyway, toxic trading takes money from real investors and gives it to the high frequency trader who has the best computer. The exchanges, ECNs and high frequency traders are slowly bleeding investors, causing their transaction costs to rise, and the investors don’t even know it.
Maybe that's what Goldman Sachs' stolen software was doing, and not front-running?