So just curious... The only stock I'm familiar wit

So just curious... The only stock I'm familiar with is ANDI.. Why would a company choose to put out info, PR's, etc after trading hours? I know Utopya likes to do that but not sure how other companies operate. I would think all new info would be put out right before trading hours or at least early in the morning so the stock prick goes up. Is there any rule on times of the day a PR or news could come out? Do other companies like to put out info after trading hours too?