Hi, I submitted an option limit order with a price within the bid-ask spread. My trade was posted at CBOE. ISE immediately posted a quote with the same price but different size. I canceled my order. The corresponding quote from ISE disappeared. I tried another option. Similar experience. Does anyone know how ISE determine its bid and ask prices ? Does any honorable ET member have a handy computer virus that I can send to ISE so that they won't interfere with my trading in the future ? Thanks.