A new approach to the understanding of the complex behavior of financial
markets index using tools from thermodynamics and statistical physics is
developed. Physical complexity, a magnitude rooted in the Kolmogorov-Chaitin
theory is applied to binary sequences built up from real time series of
financial markets indices. The study is based on NASDAQ and Mexican IPC data.
Different behaviors of this magnitude are shown when applied to the intervals
of series placed before crashes and in intervals when no financial turbulence
is observed. The connection between our results and The Efficient Market
Hypothesis is discussed.Comment: 13 pages, 4 figures, submitted to European Physical Journal