It's a long time ago I tried it, but I think IB still doesn't allow this. Which I consider kind of strange as, if I remember well, Datek does allow you to do this. Datek thus misses commissions, whereas for IB it wouldn't make no difference.
that's correct, yes. i'm not sure what you mean. although datek allows you to reverse position in one order, it charges double commission for it. - jaan
In your example it would be $10. Had you not changed the price (or tampered with the remaining 500 shares in any way), it would have been 7.50. When you change the conditions/terms, the old order is cancelled and replaced with the new one.
That's not true. The charge will still be $7.50. As long as the order is not fully executed it is always treated as a single order no matter what changes are applied after partial executions. E.g. if you start out with a 500 shares order, receive a partial execution of 400 and then change the limit price and increase the share size to 600 you will end up paying $7.50 for the full order of 1000 shares.
that's really cool. with datek, the corresponding commission would be $9.99/2 + $9.99 + SEC fee = $14.99 + SEC fee. they used to waive the fee for partials, but since this summer they don't any more. - jaan
I have not specifically tried this at IB, but at every other broker I have used, it has been treated as a new order when the parameters are changed. By your example, it seems as if I could buy shares almost endlessly (at .5 cents instead of 1 cent) by just moving the price around. I start with a limit order of 1,000 shares where the shown size is 200. I get filled for 200 and my 800 is sitting...now I change the price to further away from the inside. When I want more, I change the price again to get filled for a bit more but never my full amount (I can also keep adding to it in your example). Am I understanding you correctly...that IB (or others) would allow this?