The idea that retail investors are losing out to sophisticated speed traders is an old claim in the debate over HFT, and it’s pretty much been discredited. Speed traders aren’t competing against the ETrade guy, they’re competing with each other to fill the ETrade guy’s order. While Lewis does an admirable job in the book of burrowing into the ridiculously complicated system of how orders get routed, he misses badly by making this assumption.

via What Michael Lewis Gets Wrong About High-Frequency Trading – Businessweek.