Subject: Re: study on execution prices by popular brokerages
Ans if you use a limit and it is not executed and you miss a massive quick run-up it can cost you much more than you saved by using a limit order.

That is extremely unlikely and therefore hypothetical, unless you get greedy with your limits. I place me limit stock buy orders at the ask and sell orders at the bid, only to protect against being fleeced, not to shave a few pennies. With options I go deep inside the spread because it's more of a price negotiation with the market maker.

Elan