1. Fund fees: ETFs usually charge management fees and other related fees, which will have an impact on the fund's net value.

2. Capital flow: the net value of ETF is calculated according to the net asset value of the fund, which is influenced by investors' buying and selling behavior.

3. Stock basket adjustment: ETF's portfolio usually tracks a specific index, but the constituent stocks of the index may change.

4. Market liquidity: the transaction price of ETF is determined according to the net fund value and the relationship between market supply and demand. The market liquidity is insufficient, and there is a certain difference between the transaction price and the net value of the fund.