Subject: Re: study on execution prices by popular brokerages
Interesting study, but bear in mind that it is entirely about at-market orders. So it is primarily a measure of how much and where the market pools were taking advantage of fools.

Use limits, or you're placing a large wager on someone you don't know being nice to you. It is a nice test of who is (was) nicest in that situation, but it's not a situation that is relevant to me.

Jim