Does changing limit size bump you to the back of the queue?

Discussion in 'Order Execution' started by Raul641, Feb 20, 2007.

  1. Raul641


    Suppose the last trade is at 105, and there are 20 bids at 100.

    If I have a limit order in place to buy, say, 1 contract at 100, I'm bid #21. Suppose 10 more bids come in at 100. If I change the quantity on my open order to 2, does that bump me to the end of the queue, or do I retain my position at 21? Do I then have one bid at slot 21 and one at slot 32? Does this work differently in different markets?

    Thanks in advance for any insight.
  2. Dogfish


    If you decrease your order size you remain in place, if you increase it you go to the back, you would be better submitting a new order at the back on top of the one already queuing. In pro rata markets it would depend on the algo.

    If you are spoofing the market you can keep increasing your order by 1 lot to keep you at the back of the queue and reduce your risk of being filled. You can see this happening if you join the back of a few thousand and get a fill when only a few hundred trade. This lucky fill is a warning tht the bulk of the order is a spoof or flipper
  3. Raul641


    Very interesting, thanks for the info.

  4. dbldown


    Hmmm. Interesting. But I believe when you say if you add size on to a working order (increase) you go to the back of the line, you are referring to opening up your "order book" (TT), and clicking the up arrow to increase the size of a selected working order.

    I was under the impression that if you are say for example working a 100 lot block at a given price, you can add another 50 at the same price (not via the order book function but rather by pointing and clicking in the DOM), and the 50 lot order would be treated as a completely separate resting order. In other words, the 100 lot still holds its original place in line, and the 50 lot takes on a completely new and independent place in line. In other words, now you are working two separate orders, a 100 lot and a 50 lot, at the same price, NOT one 150 lot order.

    Lets assume we are talking about FIFO futures markets and trading with the TT DOM.

    Am I mistaken???

  5. SDticks


    Yes that's completely correct. Adding another 50 lot to your DOM in TT will be considered a seperate 50 lot order. While increasing the quantity of your existing order in the order book will drop you to the back.
  6. Dogfish


    "Am I mistaken???"

    Not at all, you just gave a longer winded version, sorry if it wasn't clear. I think we all agree :)
  7. fredcom



    I've a question close to the subject...
    How does it work if I modify only the Price Limit (say initially at 10$ and modify at 10.5$) but no change in the quantity of this buy order on stock ???

    With IB, I can submit a "Discretionary order" which is "a limit order for which you define a discretionary amount (which is added to or subtracted from the limit price) that increases the price range over which the order is eligible to execute. The original limit price is displayed to the market."
    So, I think that IB probably "modify" (perhaps it's a cancel then a new order, but I don't think so) the order when the discretionary Limit is hit...
    It's why I would like to know if this "modify" bump me to the queue.

    In advance, thanks for your help.
  8. Dogfish


  9. fredcom


    I'm going to open a new discussion.
  10. changing limit or size on the NYSE or AMEX moves you to the back of the line.
    #10     Mar 2, 2007