Forecasting commodity futures returns with stepwise regressions: Do commodity-specific factors help?

Abstract

The aim of this paper is to assess whether three well-known commodity-specific variables (basis, hedging pressure, and momentum) may improve the predictive power for commodity futures returns of models otherwise based on macroeconomic factors. We compute recursive, out-of-sample forecasts for the monthly returns of fifteen commodity futures, when estimation is based on a stepwise model selection approach under a probability-weighted regime-switching regression that identifies different volatility regimes. We systematically compare these forecasts with those produced by a simple AR(1) model that we use as a benchmark and we find that the inclusion of commodity-specific factors does not improve the forecasting power. We perform a back-testing exercise of a mean–variance investment strategy that exploits any predictability of the conditional risk premium of commodities, stocks, and bond returns, also consider transaction costs caused by portfolio rebalancing. The risk-adjusted performance of this strategy does not allow us to conclude that any forecasting approach outperforms the others. However, there is evidence that investment strategies based on commodity-specific predictors outperform the remaining strategies in the high-volatility state.

Appendix

The first group of macroeconomic variables includes output and income series, such as personal income, retail sales, and real consumption, taken from The Conference Board’s Indicator (TCB), and total industrial production, extrapolated from the Global Insights Basic Economics Database (GIBED). The second group contains labour market series. The series of average weekly hours of production or non-support workers on private non-farm payrolls, total employees in civilian labour force, and unemployment average duration in weeks are taken from the database GIBED, while the source of average weekly initial claims for unemployment insurance is TCB. The third group contains housing series. The series of total new private housing units are taken from GIBED, while the manufacturing and trade inventories are taken from TCB. The fourth group includes consumption, orders, and inventories series, such as manufacturers’ new orders series and National Association Of Purchasing Managers (NAPM) new orders index, National Association Of Purchasing Managers (NAPM) vendor deliveries index, and National Association Of Purchasing Managers (NAPM) inventories index. The fifth group includes money and credit variables. The series of monetary base, S&P 500, commercial and industrial loans, and average effective exchange rates of this group are taken from GIBED. To this series, we add the historical news-based policy index and the economic policy uncertainty index. The historical news-based policy index is a proxy of the economic policy uncertainty for the US, based on three types of underlying components: the newspaper coverage of policy-related economic uncertainty, the number of federal tax code provisions set to expire in future years, and the disagreement among economic forecasters. The economic policy uncertainty index represents the US movements in policy-related economic uncertainty. This index indicates that when the uncertainty increases, stock prices rise and the level of investment, employment, and country’s outcome go down.

The sixth group includes stock market series. They are S&P 500 Index and S&P 500 industrials series. We also include dividend yield (DY), earning price ratio (EP), and dividend pay-out ratio (DP) of S&P 500 index. The dividends used here are the 12-month moving sums of dividends paid on the S&P 500 Index. Earning price ratio is obtained as the log of earnings minus the log of stock prices where the earnings are the 12-month moving sums on the S&P 500 Index. The dividend pay-out ratio is computed as the log of dividends minus the log of earnings. We also consider stock return volatility (SVOL), which is the monthly sum of the squared daily stock returns on the S&P 500 index, and book-to-market ratio (BM), that is the ratio of the book value to market value for the Dow Jones Industrial Average. We also take into account the net equity expansion (NTIS), which is the ratio of the 12-month moving sums of net issues by New York Stock Exchange (NYSE) listed stocks to the total market capitalization of NYSE stocks.

The seventh group includes bond and exchange rate series. We additionally consider Treasury Bill Rate (TBL), which relates to the interest rate on a three-month Treasury bill, the long-term government bond yield (LTY), the long-term return government bond (LTR) returns, the term spread (TMS), the default yield spread (DFY), calculated as the difference between Moody’s BAA- and AAA-rated bond yields, and the default return spread (DFR), calculated as the difference between long-term corporate and government bond returns.

The eighth group includes prices series. They represent producer price index series, National Association of Purchasing Managers (NAPM) commodity price index, consumer of price index series, personal consumption expenditures series, and average hourly earnings of production and nonsupervisory employees series. To these, we add the crude oil price (COP), computed using the logarithmic changes in the nominal price of West Texas Intermediate crude oil, provided by the Federal Reserve Bank of St. Louis.