First of all, we should understand the meaning of basis: basis refers to the difference between the spot price of a specific commodity at a specific time and place and the futures price of that commodity in the futures market, that is, basis = spot price-futures price.

Therefore, when investors think that the basis will become larger in the future, it means that the rate of rise (or fall) of spot is lower than that of futures. At this time, you can make a profit by buying spot and selling futures.

Supplementary expansion: buying spot and futures belongs to spot arbitrage.

Other related questions can be sent to me privately at any time, hoping to help you.