Before revision: In this work we develop a new measure to study the behavior of stochastic time series, which permits to distinguish events which are different from the ordinary, like financial crises.
After revision: Following the thermodynamic formulation of multifractal measure that was shown to be capable of detecting large fluctuations at an early stage, here we propose a new index which permits us to study the behavior of stochastic time series, which permits to distinguish events which are different from the ordinary, like financial crises.