A Preference-Free Formula to Value Commodity Derivatives

This paper studies a new model of commodity prices in which the stochastic convenience yield is an affine function of past commodity returns. While preserving market completeness, the model exhibits price nonstationarity and mean reversion under the martingale measure, and, as a consequence, it is able to fit a slowly de- caying term structure of futures return volatilities. The model nests mean reversion in levels and geometric Brownian motion, and renders preference-free formulas for the prices of futures contracts and European options.