I need some help. I never paid attention to this rule, because nobody ever obeys rule, but a very good source tells me to pay attention to the rule implemented February 5, 2007 that has to do with buy ins, etc. I saw it posted on Elitetrader, and I let it slip. With the huge day the SHO stocks had, I really want to find it and study it.
I wouldn't even pay attention, but this guy is very, very good. So it must really have been implemented. All I remember is the date, that it had to do with mandated buyins. Help.