There are a few reasons that could cause your order to be cancelled:
- If your order is Immediate or Cancel, after the order matches against the book, any remaining shares will be canceled back.
- Similarly, if you place a Fill or Kill order, you are instructing the exchange to either execute the entire order or cancel it back to you.
- The duration of your order could also result in a cancellation if it has not been filled by the expiration date you've specified (i.e. GTC and GTD orders).
- If you specify Post only, on your order and it matches with an existing order on entry, your order will be canceled.
- Finally, if a symbol enters a halted trading state, any market orders or ‘Post only‘ orders will automatically be canceled.
If you have any questions regarding your canceled order please contact Support here.