Cobweb theory shows that under the condition of spontaneous adjustment of market mechanism, the agricultural product market will inevitably appear cobweb-like periodic fluctuations, thus affecting the stability of agricultural production and farmers' income. Generally speaking, the supply of agricultural products has a great response to price changes, while the demand is relatively stable and the response to price changes is small. In other words, generally speaking, the supply elasticity of agricultural products is greater than the demand elasticity. So divergent cobweb fluctuations are the most common in reality. It is an important reason for the instability of agricultural production.

In order to reduce or eliminate this fluctuation in the agricultural product market, there are generally two methods. First, the government uses relevant policies to intervene in the agricultural product market. The second is to use the adjustment mechanism of the market itself. This mechanism is the trading activity in the futures market.

The futures market is a market for trading standardized futures contracts. Futures contracts bought and sold in this market are delivered in the future. In other words, future agricultural products will be bought and sold in the futures market. In this way, we can find the future price in the process of buying and selling this future agricultural product. In other words, every trader in the futures market tries to find the future price according to the forecast of the supply and demand of the future agricultural products market. The more accurate their predictions of future prices are, the more they can benefit from futures trading. It is in their competitive activities that the futures market finds the future price. In other words, discovering future prices is one of the important functions of the futures market. Using this future price to guide production can avoid the output fluctuation caused by price fluctuation, thus slowing down or eliminating the cobweb fluctuation in the spot market of agricultural products. This is the reason why the futures market first came into being in agricultural products trading. Many economists believe that there are two reasons for the stability of American agriculture. First, the U.S. government has always been concerned about agriculture and adopted policies to protect agriculture, such as supporting prices. Second, the United States has the most developed and perfect agricultural futures market in the world.