I'm not in the industry. That said, it's my understanding that "front-running" as a term of art necessarily implies some sort of illegal behavior (at least in t

I'm not in the industry. That said, it's my understanding that "front-running" as a term of art necessarily implies some sort of illegal behavior (at least in the US and European markets), but being clever with physics (microwave towers, bouncing signals off the ionosphere, etc.) is fair game, and if you can pull off some profitable arbitrage trades with that sort of setup, you're in the clear.