John: I trade over 100K contracts per month and all of my orders are entered manually. I can tell you that what happened to you happens to me many times per day. Read FSU's post re the auction process (most Exchanges have this). Yes, this is yet another reason there are so many arb opportunities in the options market - no one will sell to you at $1.10 but then some idiot will sell at .96. Think about it - the seller was definitely a PRO. (virtually all liquidity trades in the auction process are from Pro's) The auction process (say 75% of the time) will result in a different fill (not always better). Think of it as two different markets (regular and auction). There are reasons why this "idiot" pro initially ignored your limit order. (none of them would matter to you) I've been doing Option Arb for over 20 years and the key to success is learning about these types of things. Over 70% of my fills come from MM types (machines). Very important to understand the machines and how they are programmed and also - NEVER overestimate the intelligence of the Pro's/MM's. Best of luck
Just curious how did you get this number? I know the other side of my trade is probably MM but I don't have that info in the trade reports.
estimate. There is no report as to who is on the other side of your trades. However, when you enter a buy order and get filled instantly (ie your order never shows up in the NBBO - at least you don't see it) - that is a machine selling to you. This is why you are likely better off using a fill or kill type order. Sitting limit orders typically are not the best type of order to enter. Probably 99% of all orders in the market are electronically generated
I doubt that 99% of orders are generated electronically, filled maybe but not generated. Besides very large options transactions are done OTC.