Can someone from IB please comment on this: With regard to futures trading, it has come to my attention that IB makes a practice of resubmitting already working orders to the exchange without your consent to modify a FIX tag (#77) that denotes whether you are opening/closing position. Here's a hypothetical example: ES is quoted 1300-1301, you place a limit order to short 1 at 1300.75 and are now top of book, best offer. One minute later, 2000 lots join your offer. Next, you decide to place a limit order to buy 1 at 1300.25 and are filled. Now the market is 1300-1300.75, 2001 lots on the offer and you see a 100 lot trade at 1300.75 and surprisingly you don't receive a fill. It is my understanding that upon being filled and going long, IB will cancel the opposing order and resubmit it to GLOBEX to change the FIX tag to "close position" from "open position." This causes your order to lose time priority, going to the back of the line. --- This is horrible for customers for two obvious reasons: 1) There is a huge opportunity cost in instruments such as ES where you are placed behind a huge order queue. 2) It generates excessive message traffic, which I thought IB was keen on reducing. I can only imagine how many thousands of wasteful messages are generated from cancel/replaces to modify an optional FIX tag. --- And here's my final point, correct me if I'm wrong, FIX tag #77 is optional at every US futures exchange, certainly at GLOBEX. I'm not aware of a single other futures broker that cancels your resting, working orders without your consent to modify optional FIX tags. Can someone from IB please confirm/deny if this is happening, and if so why?