I'm not familiar with Rival but I am with Spider Rock. When you enter a Vol order with or without a hedge (Buy 500 XYZ July 200 calls 31.3 Vol, it will cancel replace as the stock moves. I used Actant Quote. That can do bulk messages but exchanges only allow BDs to do that with equity options. http://www.actant.com/quote/ MAybe this will help. http://markets.cboe.com/resources/r...ng-Interface-and-Risk-Reset-Functionality.pdf
Not sure, I am only familiar with the one we are using in-house which is a registered BD and has a lot of MM-like functionality. There are a several of these services (I am blanking on several other firms that have spoken to us) and at least two others were a registered broker dealer too. It's not really about the software product they provide but rather a complete agency execution service, usually based on a complete (but somewhat dated) OMM infrastructure. If you trust a currently functional MM firm (I don't, unfortunately), either Wolverine or Ronin offers a similar service.