Several earlier studies (Ederington 1979; Johnson 1960) concluded that significant portions of the risk of price changes accompanying cash positions could be eliminated using futures contracts in various financial products over specific time periods. Based on these studies, it can be shown that the minimum-risk hedge ratio and hedging effectiveness are related to the covariance, or correlation, between spot and futures price changes, and the variance of futures price changes over the period of the hedge. This hedge ratio can be interpreted as the weight of the futures position in a portfolio consisting of both spot and futures positions, or the proportion of the predetermined spot position that is hedged contracts.