When working with a stochastic process based on brownian motion, the increments have normal (gaussian) distribution.
However, it seems that a Laplace distribution, with density:
$$f(t) = \frac{\lambda}{2} e^{-\lambda |t|} \qquad (t \in \mathbb R)$$
would fit much more returns of EUR/USD for example than a normal distribution. (Especially, it has fatter tails than normal distribution, as required).
Here in blue is the density of returns, based on 10 years of historical data of 5-minutes chart of EUR/USD. In green, the density of a Laplace distribution.
Are there some financial models, in which the stochastic process used is:
$$d \, X_t = ... + c \, d \, W_t$$
where $d\, W_t$ has a Laplace distribution instead of a normal distribution?
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