Compared with the after-hours net value of commonly traded open-end funds, etf has an additional indicator called "IOPV", which is actually close to the net value of funds. Generally, ordinary open-end funds only announce their net value after the daily closing, usually after 8: 00 pm on each trading day. As an exchange-traded fund, etf will not only announce the net value of the fund after the daily closing. The exchange will also announce the iopv of etf in real time. Etf involves three key indicators, namely iopv, net worth and price, so ipov can be understood as the real-time net worth reference of etf funds in the market. Ipov is the current net value of etf. Since ETFs can be traded in the primary market and the secondary market at the same time, iopv can be used to measure whether the real-time trading price of ETFs deviates from the price of the primary market of funds. If the primary market value of etf deviates from the secondary market value, there will be arbitrage opportunities. For example, if the primary market price is lower than the ipov price, the etf will be discounted, that is, sold at a discount. Investors can buy ETFs in the secondary market, exchange them for a package of securities, and then sell them in the primary market to earn the difference. When the etf price is higher than the iopv price, the ETF premium is generated, that is, the ETF is sold at a higher price, and investors can exchange a package of securities for the ETF to sell arbitrage in the secondary market. Because etf arbitrage has certain requirements for the amount of funds, for ordinary investors, the most direct role of iopv is to reflect whether there is a discount premium for intraday ETFs. Iopv can be calculated by the following formula: discount premium rate of funds = transaction price of fund shares-current reference net value of ETF/current reference net value of ETF * 100%. If the discount premium rate is positive, it means ETF premium, if it is negative, it means discount. If the premium rate of an etf fund is too high, it means that the etf is hot in the market.