[kbelder]

I've wondered if introducing a small but omnipresent random delay in all trading requests might suffice. Something like 0-100 milliseconds. Just enough to moderate some of the advantage that physically co-located automated traders have, while not outright banning it.

[steveBK123]

It's an interesting idea, IEX basically did something non-random with introducing latency.

A consideration is once you do this, the business model of exchanges changes a lot (they make a ton of money on colo).

So they need revenue elsewhere, so maybe free retail trading goes away again, who knows.