I have an innovative stochastic process that I have been testing (paper-trading) with US equity options that is showing good gains. My VC backers are about to commit approx $1m for real-time testing. The strategy I have been employing is delta-neutral and relies on calibrating the model to the options market and trading contracts that are out of line. I am looking for a brokerage/electronic trading service that 1. Permits multiple small trades (even single contracts) daily 2. Has portfolio margining (separate margining of individual contracts would destroy my leverage) 3. Has fast execution 4. With minimal fees 5. Optimally (but perhaps not essential) gurantees full execution or none for multi-leg combos. Ideally there will be an electronic platform that enables me to get a full option chain (up to 2-300 contracts in some cases) into my own valuation software (VC++) and accepts trade orders by return. Suggestions have been made concerning high-priced brokers that seem, by my estimation, to require me to have at least $100m to trade! I have looked at Interactive Brokers' web-site. They look as though they can handle the job except that they might not provide me with a full option chain. I posted a request to them for a contact person, but no one has got back to me. I have seen some comments here regading IB, so I imagine there are some people with substantial experience of them. Can someone comment on their suitability for my requirements or on alternatives?