The impact of investors in agricultural commodity derivative markets

The objective of this paper was to test whether investing activity in the futures markets of different commodities (grains, sugar, coffee, cotton, cocoa, livestock) could be identified as a source of the increasing level and volatility of agricultural commodity prices. The causal link between trading activity and market factors (returns, volatility) can be investigated using weekly data, usually derived from the Commitment of Traders Reports released by the US Commodity Futures Trading Commission (CFTC), or daily data expressed as the ratio of volume to open interest (VOIR). To increase the power of the estimation process and investigate the role of causal variables to determine the trends of all the market factors, the authors tested the estimates obtained by seemingly unrelated regression (SUR). One innovation is represented by the evaluation of the inverse relationships between market factors and causal variables. The market factors were also tested as causal variables, avoiding giving priority to only one part of the relationship according to Granger's causality. The lack of significance revealed by the Granger causality test on weekly models could be due to the inappropriate frequency of the information. The ratio of volume to open interest in futures contracts performs better than other parameters extensively adopted in the literature. The likely reason is that it depends on the daily frequency of this parameter, which provides statistical evidence of phenomena that include their effect in weekly intervals. The estimations for the daily model provide statistical evidence of a mutual relationship only between trading activity and realized volatility. No causal relationships were found for returns. The behaviour of all 12 futures markets examined is quite similar and uniform with respect to the scale of the coefficients and their temporal profile.