Its not the 'Why' but the 'How' you are dealing with in intraday trading.
There were 4 downmoves into the YM close (4pm): from 15.16 in sequence - 136, 200, 120 and 162 points down, separated of course by 3 reversals (upmoves). Lets deal with the last downmove. Starting at 15.47.40 and only...