Leverage principle is the charm of futures investment. Futures market transactions do not need to pay all the funds, and domestic futures transactions only need to pay 5% margin to obtain future trading rights. Due to the use of margin, the original market has been enlarged ten times. Assuming that the daily limit of copper price closes on a certain day (the daily limit in futures is only 3% of the last trading day), the operation is correct. The return on capital is as high as 60%(3%÷5%), which is six times the daily limit of the stock market.