"The insiders are able to move faster than you," Lewis said on "60 Minutes" on Sunday night. "They're able to see your order and play it against other orders in ways that you don't understand. They're able to front run your order."
The advantage adds up to less than a second -- in some cases a fraction of a millisecond -- but thanks to the powerful computers masterminding the trades, it's enough time to make serious money.
"One hedge fund manager said, 'I was running a hedge fund that was $9 billion and that we figured that the, just our inability to, to make the trades the market said we should be able to make was costing us $300 million a year.' That was $300 million a year in someone else's pocket," Lewis said.