"Half a second" was not meant to mean "enforce a delay of precisely 500000 microseconds". The point is that the problem would be solved if traders would chill out for the blink of an eye. The fact that it's hard to force people to chill out is a completely separate issue.
> To be clear, your concern is strictly that if a hedge fund is buying a very large amount of stock, this will cause the price to move against them as people react to it,
> in the specific case you list: No, I don't see why that's bad.
The original scenario has nothing to do with order size. The scenario is that X sends a simultaneous order to multiple exchanges, but while it's still in transit to most of the exchanges Y reacts to the order and submits their own on a faster cable, getting there before the order they're reacting to. I think such an outcome is clearly bad. I won't suggest a fix to avoid distraction. Do you disagree with it being bad? Picture it happening to an old lady if you have no sympathy for hedge funds.
> To be clear, your concern is strictly that if a hedge fund is buying a very large amount of stock, this will cause the price to move against them as people react to it,
> in the specific case you list: No, I don't see why that's bad.
The original scenario has nothing to do with order size. The scenario is that X sends a simultaneous order to multiple exchanges, but while it's still in transit to most of the exchanges Y reacts to the order and submits their own on a faster cable, getting there before the order they're reacting to. I think such an outcome is clearly bad. I won't suggest a fix to avoid distraction. Do you disagree with it being bad? Picture it happening to an old lady if you have no sympathy for hedge funds.