Along with Mello and Parsons (1995a, b), Edwards and Canter (1995a,
b) argue that MGRM was overhedged because short-term oil futures prices
tend to be much more volatile than prices on long-term forward contracts.
According to these authors, MGRM’s managers could have—and should
have—designed a hedge that would have reduced the variability of the firm’s
short-term cash flows. Edwards and Canter find that the correlation of shortterm
energy futures and forward prices with long-term prices is approximately
50 percent. Thus, they argue that MGRM could have minimized the variance of its cash flows with a hedge approximately 50 percent smaller than the total of its
future delivery commitments.9 Mello and Parsons observe that the exact size of
a minimum-variance hedge is difficult to calculate because MGRM’s contracts
gave its customers options to terminate their contracts after three years. They
find that the minimum-variance hedge ratio could be as high as 75 percent if
one assumes that all such options would be exercised at the end of three years.