The role of inventory in explaining the shape of the forward curve and spot price volatility in commodity markets is central in the theory of storage developed by Kaldor [Kaldor, N. (1939) "Speculation and Economic Stability", The Review of Economic Studies 7, 1-27] and Working [Working, H....

The goal of this paper is to present a model for the joint evolution of correlated commodity forward curves. Each forward curve is directed by two state variables, namely slope and level, and the model is meant to capture both the local and global dependence structures between slopes and levels....