http://www.npr.org/2014/04/01/297686724/on-a-rigged-wall-street-milliseconds-make-all-the-difference
From the interview summary:
You'd be surprised to hear what investment banks do to get that nanosecond edge, and how they often use it in ways Lewis describes as predatory. The victims range from some investment houses to individual investors. Lewis says high-frequency trades can end up hurting the returns on your retirement accounts. The FBI, Wall Street regulators and New York's attorney general are investigating high-frequency trading, and whether it has created an uneven playing field.