I think you're confusing two different issues. If a retail customer's order is actually sent to an internalizing firm, then trading ahead of it would be _actual

I think you're confusing two different issues. If a retail customer's order is actually sent to an internalizing firm, then trading ahead of it would be _actual_ front-running, is already illegal [1], and is taken very seriously by the regulators. What Lewis _calls_ front-running in his book is something completely different, and involves reacting quickly to public information rather than misappropriating private information. [1] http://en.wikipedia.org/wiki/Manning_rule http://en.wikipedia.org/wiki/Manning_rule