Compared with the open foundation, the risk of closed foundation is relatively small. There are net value and market price on the back cover, which are traded at market price in the stock market. So there is a discount rate, discount rate = (net value-market value)/net value. Usually (referring to the general back cover, except the leveraged back cover), it can be bought and sold at a market price below the net value. This discount rate is equivalent to a safe boundary. The greater the discount rate, the greater the margin of safety. In addition, the scale of the base seal is fixed, which is conducive to the operation of the fund manager. In addition, in the case of unilateral decline, the stock position of the base can be lower than that of the stock type. These constitute the characteristics of relatively open base and relatively anti-falling. Understanding the risks from these aspects is relatively small. But there are still risks, so be careful!