Gorton and Rouwenhorst (2006) examined commodity futures returns over the period July 1959 to December 2004 based on an equally-weighted index. They found that fully collateralized commodity futures had historically offered the same return and Sharpe ratio as U.S. equities, but were negatively correlated with the return on stocks and bonds. Reviewing these results ten years later, we find that our conclusions largely hold up out-of-sample. The in- and out-of-sample average commodity risk premiums are not significantly different, nor is the cross-sectional relationship between average returns and the basis. Correlations among commodities and commodity correlations with other assets experienced a temporary increase during the financial crisis which is in line with historical experience of variation of these correlations over the business cycle.
For this study of the simple properties of commodity futures as an asset class, an equally weighted index of monthly returns of commodity futures was constructed for the July 1959 through December 2004 period. Fully collateralized commodity futures historically have offered the same return and Sharpe ratio as U.S. equities. Although the risk premium on commodity futures is essentially the same as that on equities for the study period, commodity futures returns are negatively correlated with equity returns and bond returns. The negative correlation is the result, primarily, of commodity futures’ different behavior over a business cycle. Commodity futures are positively correlated with inflation, unexpected inflation, and changes in expected inflation.