Empty list originally means poor, poor. Extended meaning: in the foreign exchange and futures markets, even if there is no commodity, you can make a profit by selling it.

It is used in foreign exchange, futures market and stocks. The futures market is a place for futures trading and the sum of all kinds of trading relationships.

That is, when we sell a contract at a high price and then buy it back at a low price, the difference between the sale and the purchase is our profit. This kind of order is also called an empty order.