Quote from def:
No, TH does not trade against clients.
...
However, given TH is a market maker that does a substantial share of business providing liquidity globally. there is a chance that TH may be on the other side of your trade that takes place on an exchange. There also is a chance that the other side of your trade might be another IB client or perhaps Goldman Sachs, SAC, Renaissance, Knight, CSFB, etc.
You're either being disingenuous, or you haven't read your company's own Web site:
http://www.interactivebrokers.com/en/general/education/faqs/timberhillAutoExeService.php
D) of its own clients sending their orders to a real exchange?