As I understand it, the law is that they're not allowed to trade while in possession of material, non-public information, but beyond that most of the practices

As I understand it, the law is that they're not allowed to trade while in possession of material, non-public information, but beyond that most of the practices are there to just entirely avoid the suspicion or appearance of foul play. Sometimes executives are allowed to trade during windows immediately after announcing results, etc. The law would still dictate that they do not trade if they know about upcoming acquisitions or changes, etc. but someone would still have to prove that, and it's a risk that is removed if the executive just follows a preset schedule.