Non-gaussian behaviour of some commodities prices José Augusto M. de Andrade Jr Tabajara Pimenta Jr (PhD)
Agenda Introduction Stylized facts Impacts over financial engineering Data and methodology Discussion of empirical results Conclusions
Introduction Pareto law Bachelier(1900) Mandelbrot(1963) & econophysics Black & Scholes options pricing formula Stylized facts
Stylized facts High kurtosis (>3) – heavy tails – Noah effect Volatility clustering Long-term memory (Hurst & Joseph Effect) Scaling
Impacts over financial engineering Options & stocks pricing (B&S formula) Brownian motion – Wiener process S(T) = S(0) exp ( [ r – 1/2 σ 2] T + σW(T) ) CAPM Risk / Return – Covariance / Variance Risk Unconditional distribution Markovitz portfolio optimization model Variance / covariance
Data and methodology Data
Methods Non-parametric tests for normality BDS test for i.i.d. Kolgomorov-Smirnov Chi-square Shapiro-Francia Shapiro-Wilkinson Anderson-Darling BDS test for i.i.d.
Discussion of results
Results
Conclusions The commodities log-returns analysed are not gaussian They are not i.i.d. – so the underlaying process is nonlinear stochastic (non-Gaussian) or deterministic (chaos) The financial engineering tools are based on gaussian assumptions So, these tools cannot give reliable results as they are based on false assumptions
Further research Another distribution – stable paretian models Petrobras paper – the results