Market value profit and loss is a virtual concept, which does not directly affect the disposable funds of investors. Generally speaking, the daily mark-to-market gains and losses will be calculated and tracked in real time, but in fact, these gains and losses are not really realized, but only reflect the current value changes of assets in the market. When the mark-to-market gains and losses occur in the account that the investor is responsible for, these funds will not be transferred into or out of the investor's account immediately. On the contrary, these gains and losses are accounted into the value of assets in the account, and only when investors choose to sell assets will the actual gains and losses be converted into the actual inflow or outflow of funds in the account.