rrk, i agree, but i think its more of a case of 'informed'...

rrk, i agree, but i think its more of a case of 'informed' trading i.e., someone knows WHEN the announcement is going to be released, but dont know the exact details of whether it will be good or bad. Could easily have come from a friend of a friend that knows him that works for the company or did some work for them and overheard a conversation, blah blah blah. OR Other traders/investors can also see the movement in share price before the ann is made and just jump onto the bandwagon, not knowing really whether the news is good or bad - still a case of 'informed' trading
Insider trading on the the other hand is illegal - people get sent to prison if caught..