  Changes (returns) in stock index prices and exchange rates for currencies are
argued, based on empirical data, to obey a stable distribution with
characteristic exponent $ \alpha < 2 $ for short sampling intervals and a
Gaussian distribution for long sampling intervals. In order to explain this
phenomenon, an Ehrenfest model with large jumps (ELJ) is introduced to explain
the empirical density function of price changes for both short and long
sampling intervals.
