If I understand correctly, accounts tagged as pattern day traders have 4:1 buying power. However, at the end of each day, Regulation T says that you must have 50% margin, which means that your max leverage at the end of the day cannot be greater than 2:1. Therefore the broker will start liquidating your account near the close if you're above 2:1. Is this how it works? IF yes, how can someone maintain 4:1 on overnight positions?