It was interesting and slower than I expected when I first saw one. The types of options I used to trade were situations when the ask was 2x to 3x the bid. Before I was about to buy one, all of the sudden, the bid was rising by the minimum tick for what looked like a few ticks per second. The total bid size was high and fluctuating the entire time. It could have been multiple algorithms all more or less operating the same way and/or matching the lead bid since the leading algorithm had already tested that price. It must have not liked how high the market was willing to sell, so it stopped. I watched it for a little longer, gave up, and started working my order.