The bidders could be in possesion of material non-public information and could trade on it unless they made them sign a trading form before hand. If they didnt demand this, one or more parties could be trading on that info....legally I think.
But even obviously illegal insider trading happens fairly often.
I mean, you get to keep the money for a few years and then pay it back...if you still have it and they slap your wrist and make you promise not to do it again.
Im holding the shares I paid 70 cents for. I will wait it out & collect whatever Sellers does I guess. (Less his salary & kickbacks)