If the net value of the fund is lower than the investor's position cost after the fund falls, then the investor can increase the position, which can reduce the investor's cost. The lower the cost, the smaller the risk that investors bear, and the higher the probability of fund's subsequent recovery and making money.

If the net value of the fund is higher than the investor's position cost after the fund falls, then the investor can lighten or hold the position without adding the position. At this time, adding positions will increase the cost of investors, which is not cost-effective for investors.