buy stars when they are cheap .
sell if they are pricy.
the price changes every hour .
it depends on BOX OFFICE HITS
suppose------------------------------
srk's price is Rs. 500
if his film do not get a good response or his movie is not good (obviesly not)
then his price will dip eg. 450
and after that he done some 2-3 good BLOCKBUSTER HITS
then
price will be reaching at the top eg.600-950
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PS : the price changes on purchase also