An importer imported copper from abroad at the price of 17000 yuan/ton in May, and has not found a buyer yet. In order to avoid the risk of future price decline, the importer hedges in the futures exchange and sells a futures contract that expires in three months at the price of 17500 yuan/ton, then the basis at this time is -500 yuan/ton, and actively seeks buyers in the spot market. In mid-June, a copper factory thought that copper prices would continue to fall, and was unwilling to set prices at that time. Through negotiation, both parties agree that the price of futures contracts that expire in August is 100 yuan/ton, and the buyer, that is, the copper pipe factory, determines that the futures contracts will expire on any day from the trading hours of Shanghai Futures Exchange in August to August 1 5. In August, the August copper contract price of Shanghai Futures Exchange fell to 15700 yuan/ton, and the spot price was 15 150 yuan/ton. The copper factory thinks that the copper price has fallen to the bottom, and decides to calculate the spot transaction price at this price, so it informs the importer's futures broker to buy the August copper futures contract in the name of the importer (the buyer and the seller have an authorization agreement in advance). At this time, the importer sells at the spot price of 15700 yuan/ton-100 yuan/ton = 15600 yuan/ton, and closes the futures market at the price of 15700 yuan/ton, thus ending the hedging transaction. Based on the above, the details of the importer's transactions are shown in the following table: the basis of the spot market futures market. In May, the importer imported electrolytic copper from abroad at the price of 17500 yuan/ton and sold the expired futures contract -500 yuan/ton in August at the price of 15600 yuan/ton, and the agreed basis for closing the position was-100 yuan/ton, resulting in losses 1400 due to the importer's At this time, the hedger can stably obtain the profit per ton of 400 yuan, so as to increase the profit and realize hedging. Assuming that the copper price rises instead of falling in August, the copper factory decides to take this price as the benchmark, and there are: in May, the spot market futures market basis imported electrolytic copper at 17000 yuan/ton, and in June, the expired futures contract was sold at 17500 yuan/ton -500 yuan. The buyer takes the transaction price from August 1 to August 15 as the benchmark price. The basis difference is-100 yuan/ton. In August, it was sold at 17900 yuan/ton [17250] and closed at 18000 yuan/ton. The agreed base price is-100 yuan/ton, resulting in a profit of 900 yuan/ton and a loss of 500 yuan/ton of 400 yuan/ton). The importer will generate a profit in the spot market (18000-100)-17000 = 900 (yuan/ton). Although the futures market will lose 500 yuan per ton at this time, the importer will gain 400 yuan/ton steadily after the two are offset.

In this case, if the basis transaction is not completed, the selling hedger has to end the selling hedging transaction under the condition of narrowing the basis. At this time, the basis has changed from -500 yuan/ton in May to -550 yuan/ton in August, and the basis has expanded, so the ideal hedging effect cannot be obtained. Spot market futures market basis imported electrolytic copper 17000 yuan/ton from abroad in May, sold at 17500 yuan/ton -500 yuan/ton, and sold at 1565438 yuan/ton in August, bought at 15700 yuan/ton -550 yuan/ton.