Simple question: If the current Bid is 24.78 and I place a Buy Limit order at that price, should the size of the Bid increase immediately? In other words, am I bidding so that somebody selling at Market can sell to me right away, or is my order simply going to not exist and then be converted to a Market order once the Ask price hits it? Sub-question: I ask this because I've been paper trading with eSignal and IB, and it seems that my Buy Lmt often gets above the Bid, and it seems to be getting hit more around at where the Ask is at the time, though I'm not entirely sure as it happens quite fast. I'm guessing this would change when using my real account (since it would be a real bid and would have to show in T&S), so that the Bid cannot go under my Buy Limit order. Does this mean paper trading isn't quite as "realistic" as it should be?