For example, if you buy some kind of copper now and plan to sell it or use it for yourself in three months, you will have to pay the cost of storage and custody during these three months. And if you buy a contract in the futures market after 3 months, then you only need to wait until 3 months after delivery, you can get the spot and handle it yourself. For these three months, you have no expenses.

So you can see that the futures price should be based on the spot price plus the so-called position cost (that is, if you buy the spot and hold it for 3 months), so the futures price is higher than the spot most of the time.

However, the market factor that affects the price is the relationship between supply and demand. When demand exceeds supply, spot prices will soar. In other words, if the supply exceeds the demand, the market's expectation of future prices will drop, so the response of futures will be more sensitive and the decline will be greater. In both cases, the futures price will be lower than the spot price.