Which economic hero can tell me how the two tycoons lost their property in the final futures trading part of the movie "Upside Down"?

That is short selling. Generally, this kind of transaction is operated by paying a deposit. For example, I have 100 yuan to buy something at the original price. Under normal circumstances, I can only buy and sell one. Pay a certain percentage of deposit, such as 20%, and I can use 100 as 500( 100 yuan is 500 yuan's 20% deposit). If you think the price will drop in the future, you can pay a deposit of 100 yuan, borrow goods from 500 yuan and sell them. When the goods drop to 80, you can buy goods from 400 yuan and return them. At this time, you sold 500, bought 400, and earned 100 yuan. Leverage can greatly expand the benefits. The above reduction is 20%, and the principal income is doubled. Of course, the risks are also great. Once it rises by 20%, it will be completely lost, instead of just losing 20% of the principal. This is five times the leverage, and the risks and benefits will be expanded five times at the same time.

It is said that the recent decline in gold is manipulated by Wall Street bosses, who are more leveraged and have 20 partners.