If you are short at the opening on the date goes ex- dividend you have to pay the dividend? if you go short during the day you do not have the pay dividend? are these statements correct?
If you are short Before ex date (ex date-1),you have to pay the dividend. If Tuesday is ex date and you are holding short on Monday closing of after hours trading (20:00 Hours) than only you pay dividend. Trading on ex div date (pre market or opening or during day) has no affect.