Short selling refers to the phenomenon that market manipulators take advantage of capital or physical goods to sell a large number of futures contracts in the futures market, so that their short positions greatly exceed the ability of many parties to undertake physical goods, which leads to a sharp drop in futures market prices, forcing speculative bulls to sell their contracts at low prices, or being punished for breach of contract because of their financial strength. The phenomenon of forcing the air can make market manipulators reap huge profits. When the spot supply is sufficient and the investment capital is too small, it is easy to have too much vacant space. Spot traders may short the futures market to hedge, and market speculators have to close their positions and leave when the spot supply is sufficient and the hedging funds are strong.

"Forced liquidation" refers to the behavior of futures exchange members or customers who use their financial advantages to control futures trading positions or monopolize spot commodities that can be delivered, over-position and deliver, forcing the other party to breach the contract or close the position at an unfavorable price, so as to reap huge profits. Contrary to empty forcing, empty forcing is two ways to force positions.