Price Discovery in Commodity Futures and Cash Markets with Heterogenous Agents

The paper develops a price discovery model for commodity futures markets that accounts for two forms of limits to arbitrage caused by transaction costs and noise trader risk. Four market regimes are identified: (1) effective arbitrage, (2) transaction costs but no noise trader risk, (3) no transaction costs but noise trader risk and (4) both transaction costs and noise trader risk. It is shown that commodity prices are driven by both market fundamentals and speculative trader positions under the latter two regimes. Further, speculative effects spill over to the cash market under regime (3) but are confined to the futures market under regime (4). The model is empirically tested using data from six grain and soft commodity markets. While regime (4) is rare and short lived, regime (3) with some noise trader risk and varying elasticity of arbitrage prevails.