We address the issue of stock market fluctuations within Langevin Dynamics
(LD) and the thermodynamics definitions of multifractality in order to stud
y its second-order characterization given by the analogous specific heat C-
q, where q is an analogous temperature relating the moments of the generati
ng partition function for the financial data signals. Due to non-linear and
additive noise terms within the LD, we found that C-q can display a should
er to the right of its main peak as also found in the S&P500 historical dat
a which may resemble a classical phase transition at a critical point.