additive source of noise. Depending on the parameters of the process, the additive or multiplicative contributions will play the dominant role. This gives rise to a rich spectrum of PDF shapes, in particular, a subclass with two-fold power-law behavior, both above and below the mode, providing a general realistic framework for describing the shape of empirical distributions. A comparison with experimental results is presented in Sect. \[Sec:empirical\]. Finally, Sect. \[Sec:final\] contains the main conclusions and general remarks.

Mean reversion and multiplicative fluctuations {#Sec:props}
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The reversion to the mean is one of the basic ingredients to describe the dynamics of several stochastic variables of interest in economy. It is fundamental since it concerns the behavior around a central value $\theta$ and reflects the global market response to deviations from a consensus or equilibrium level. It depends on monetary unit, market size, degree of risk aversion, etc., hence, it is characteristic of each market. The aversion to deviations from the mean needs not be linear, specially when large deviations are involved. Similarly, a nonlinear mechanism due to the cooperative behavior of traders, rules the way the market modulates the amplitude of fluctuations (mainly external) giving rise to innovations.

We consider the 