In order to better understand how limit and stop limit orders work on Globex, I have found the following links to be of help : http://www.cme.com/get/abtglx/enterorder987.html http://www.cme.com/get/abtglx/matalgorit965.html http://www.elitetrader.com/vb/showthread.php?s=&threadid=19650 http://www.elitetrader.com/vb/showthread.php?s=&threadid=10982 http://www.elitetrader.com/vb/showthread.php?s=&threadid=10610 Assume for the moment that my interest lies in a "fat finger" event and not a price shock due to some external event (eg. Saddam etc). In other words, assume for the purposes of this example that for the small delta in time before and after an order to, say, sell 100,000 ES is executed, there are no additional protective measures undertaken by other market participants (how could they know), and the market depth picture stays more or less the same. Also assume before the button is pressed that : (a) the market is at 1008.00 X 1008.25, last price 1008.00. (b) Mr. Fat Finger's (MFF) order is to sell 100,000 ES limit 993.00. (c) I am long and have a stop limit order (native to Globex) to sell at 1003.00 with a 5 tick limit. My questions are : (1) Does MFF's order have priority over any of the pre-existing stops below 1008.00? (2) Assuming that when it reaches 1003.00 there are still some stops limit orders unexecuted (eg. sell at 1003.50, 5 tick limit), do these have priority over my order? (3) Assuming no new orders are placed after the "event", who else, apart from (1) and (2) above, can get priority over my order? (4) Assuming new orders are placed after (and because of) the "event", who else can get priority over me? I appreciate your replies - however, when answering, please just refer to the mechanics of the system and not to the general philosophy of stop protection against fat finger events given that the price usually quickly reverts to pre-event levels, trades are broken under certain circumstances etc.