  We test whether the futures prices of some commodity and energy markets are
determined by stochastic rules or exhibit nonlinear deterministic endogenous
fluctuations. As for the methodologies, we use the maximal Lyapunov exponents
(MLE) and a determinism test, both based on the reconstruction of the phase
space. In particular, employing a recent methodology, we estimate a coefficient
$\kappa$ that describes the determinism rate of the analyzed time series. We
find that the underlying system for futures prices shows a reliability level
$\kappa$ near to $1$ while the MLE is positive for all commodity futures
series. Thus, the empirical evidence suggests that commodity and energy futures
prices are the measured footprint of a nonlinear deterministic, rather than a
stochastic, system.
