======= Arl; Dont see anywhere it is written they couldnt do that, however; Ox, to put it simple has always filled my puts , or calls on one exchange, at a time. Differing perhaps from what you mentioned; separate scale in orders /, same strike, sure.
I believe the way we handle it is unique, as we take the risk of one side of the order not being filled. Here's a page where you can see the logic used for spread routing. Clicking on any of the boxes will reveal detailed information. http://www.interactivebrokers.com/php/webhelp/spreads.htm
Does anyone have a recommendation as to what the best platform/front end for executing these option spreads across markets on my own is (where I would accept the risk that the software may not get all the legs filled).
I don't know who the best is, but I can tell you that OXpress is flat-out awful. To leg a spread, you need serious speed. OXpress browser-based interface is slow and the ability to get out fast (cancel) is even slower. If it's going against you, you can get wiped out.
I couldn't understand the IB diagram on the example of partial fills, but I'm interested in this feature. Can you give an example of, say, an INTC option spread (any options within INTC), and walk us through how this would work on a partial fill? Thanks.
Say you want to buy a 5 lot straddle at a price of $7. If an best offer for the call is at the ISE with a price of 3.75 and the best for a put is on the PSE at 3.25 IB will send out orders to both exchanges in search of a fill. However, say 5 lots of the call get filled but in the split second it takes for the 5 lot order for the puts to reach the PSE, the size drops to 2 offered at 3.25 and only 2 get filled. If this should occur, IB will return an execution to you of 2 straddles and "eat" the 3 lots remaining on the call.