In its latest email, IB sent out a link to a page with updated rules for option orders. Here's the link: http://www.interactivebrokers.com/index.html?html/companyInfo/opt_exch_rules.html~top.body In there, it talks about how you can only place one order on the same side of the market in the same option class every 15 seconds. So basically, if you wanted to increase your position, you'd have to wait 15 seconds before doing so. But even stranger is the rule about the CBOE where you can't send multiple orders on the same option at all. Is this common at other option firms?