On 9/19 I sold IYF on the ARCA opening cross at 94.00. While the opening price was 35% higher than the previous close there was no reason to suspect that 94 was a bad price that would be canceled. 9/19 was a volatile day. Another stock I have, MS, opened up 42%. I can cite dozens of examples of extreme price moves. Now I find the trade has been busted. My datastream shows the trade corrections starting at 7:40 pm that evening. I had no chance to exit during the day. I feel screwed. I know ARCA posts many extreme executions that defy commonsense, but this one does not fit given the conditions on 9/19.