It refers to signing a contract with a (designated investment) bank, opening a trust investment account, depositing a sum of money (margin) as a guarantee, and setting a credit operation limit (that is, 20-400 times) by the (investment) bank (or brokerage house) leverage effect, more than 400 times is illegal). Investors can freely buy and sell spot foreign exchange of the same value within the quota, and the profit and loss caused by the operation will be automatically deducted or deposited from the above investment account. Allow small investors to use smaller funds to obtain larger transaction quotas, enjoy the same use of foreign exchange transactions as global capital to avoid risks, and create profit opportunities in exchange rate changes. Generally speaking, foreign exchange speculation is an investment behavior.