 One choice would be to continue to hold the stock overnight, and risk a large loss of capital.The other choice would be to close the position, protecting his capital, and (perhaps inappropriately) fall under the day-trading rule, as this would now be a 4th day trade within the period.Of course, if the trader is aware of this well-known rule, he should not open the 4th position unless he or she intends to hold it overnight.