In most stocks I have experienced people do weird orders at open...

In most stocks I have experienced people do weird orders at open or close. For example a stock might be trading for $1 or thereabouts all day and at close someone will put in a sell order at 50c. The difference here is that with a not very liquid stock those stupid orders dont necessarily get masked by all the other orders. In a way, I'm happy that happens sometimes, it serves them right and occasionally you can be on the other side of the trade. For heavily traded (liquid) stocks you have the other problem that open and close is controlled by non retail investors who have access to orders which we cannot use (hidden volume, dynamic orders, ...). If you are a trader you need to come to terms with how others operate but if you are a long term investor just brush it off - the SP will revert back to its true value soon enough.