First of all, the principle of arbitrage lies in the change of price difference. What you said is that the price difference has changed, but what you said is equal to not saying, because between two contracts or varieties, you can't tell who is rising fast and who is rising slowly. What you see is the past tense, and you don't know if it will happen again. If you do it by speculation or expectation, it is not arbitrage, but bilateral speculation.

Strictly speaking, arbitrage does not pay attention to the ups and downs of megatrends, nor to the ups and downs of each variety or contract. We only study one data, which is the price difference. Usually, the method of probability research is used to find out the fluctuation range from the historical price difference, and then we can know whether it is too big or too small now. For example, in history, the price difference between beans and soybean meal was 500 to 2000, and now it is 2000, so we say that the price difference is too big and the soybean meal is empty.

Of course, there are many ways to study the price difference. You can find relevant information about this.

The common arbitrage method is risk-free arbitrage, usually intertemporal arbitrage, such as copper 1007 and copper 1008. The reasonable price difference between the two contracts can be calculated, which is nothing more than interest, storage fees, transaction fees and so on. If the actual price difference is higher than the reasonable price difference, it is to buy short months and long months. If the price difference is settled, close the door and make money. The price difference will not be settled, and finally it will be delivered to make money.

I said a lot, I don't know if you can understand. Contact me if you have any questions. I hope it helps you.