I believe that it is largely predetermined what will happen on...

I believe that it is largely predetermined what will happen on an announcement, before the announcement takes place , depending on whether the big guys are ready to take a share up or not . Also I have noticed that if the sp is already in overbought territory , it is not usually going to go up and stay up on a good announcement. It has to come down first before it can go up, and have that rise sustained .  It would usually be a combination of what the news is , and where the share is sitting technically at the time of the news. Which is why we so often hear of shares not responding appropriately to good news . But then again , I am pretty useless at fundamental analysis. So it is hard for me to work out if news is good or not anyway . And the threads aren't much help , as lots of folks are usually there dogging the good shares . Or pumping the ones that are about to plunge .