A more widely used device is the buying and selling of futures contracts on the commodities exchange. All individuals or firms holding agricultural commodities for which futures markets are available may guard -- "hedge" -- against price changes. Essential marketing services are performed by the people who run the futures exchange and enforce its trading rules, the brokers who act as agents on the floor of the exchange, and the speculators who assume the risks and thus make hedging possible. Retailers are protected to a degree against change in price by the practice of pricing goods on.
