Buying entrustment and selling entrustment in futures trading. Buy one refers to the commission with the highest price among buying commissions, and sell one refers to the commission with the lowest price among selling commissions. This is a term used in futures trading to describe the entrustment relationship between buyers and sellers in the market. In futures trading, investors can earn profits by buying and selling futures contracts, so buying one and selling one refers to the buying and selling commission in futures trading.