Why does the futures have to pay back the principal? This stems from the margin system of futures. In the process of contract trading, futures investors do not need to pay the full contract value, but only need to pay a certain percentage of margin to participate in investment trading. For example, the price of a soybean meal futures contract is 2800 yuan per ton, and a contract represents 10 ton. Without the margin system, it costs 2800X 10=28000 yuan to buy a first-hand contract. With the margin system, the margin rate is 15%. Then, the amount to be paid for purchasing a contract is: 2800 x10x 15% = 4,200 yuan, which is equivalent to the original price of the goods and can be bought at the price of15%. If the contract price drops by 10%, that is, the price per ton of soybean meal drops by 280 yuan, the investors in the next contract will lose 2,800 yuan, and if the investors only contribute 4,200 yuan, they will lose 2,800 yuan, accounting for 66% of the loss. If the contract price drops by 500 yuan, the investor has already lost 5,000 yuan, which has exceeded the principal paid before, so that we can. Due to the existence of the deposit system, the fluctuation of the contract value itself is much higher than the principal invested by us, which leads to the situation of paying back the money after the loss of the principal. Margin trading of futures is to increase the leverage in trading and amplify the risk of trading. You may lose more and earn more. In the actual operation process, except in extreme cases, such a situation rarely occurs. Generally speaking, futures companies will do a good job in risk control and remind customers in time. Nevertheless, investors involved in futures trading should be reminded of the risks.