It is better to add positions when the fund falls, which can reduce costs. After that, the probability of the fund returning to the capital to make money is higher. Funds are traded on a net basis. After the fund fell, the net value decreased, and investors gained more fund shares with the same funds, which diluted the transaction cost of the fund.

Investors can decide whether to increase their positions a few minutes before the close, depending on the fund's net worth estimate. If the net value is estimated to rise, it will not increase the position, and if it falls, it will increase the position.