We specify a principal-agent marketing channel involving producers, wholesalers, retailers and a futures market. Our hedge ratio for producers appears to be much lower than the common price-risk minimising ones as we account for producers' vertical contracts and, by using annual data, their production horizon. The Dutch ware potato marketing channel and its futures market in Amsterdam show that possibly through decreases in producers' and wholesalers' risk aversions, their optimal dynamic hedge ratios decreased from 38% and 12%, respectively, in 1982 to 18% and 10%, respectively, in 2003. These results comply with the decreased futures volume traded in Amsterdam over the years.