After part of the fund is sold, the cost of holding the fund may change. For example, an investor buys a fund 1000 at the price of 5 yuan, and the cost of holding the fund is 5 yuan. When the fund rose to 6 yuan, investors sold 500 shares. At this time, the investment holding cost is (5000-3000)/500=4 yuan, and the holding cost is reduced.

If it falls to 500 points in 4 yuan, the cost of holding positions is (5000-2000)/500=6 yuan, and the cost of holding positions will increase.

To sum up, the cost of selling some positions by the fund may change. If it becomes lower, investors will make money. On the contrary, if you increase it, you will lose. If it doesn't change, it won't lose money.