Fixed investment in a fund refers to investing in a designated open-end fund at a fixed time and amount. By constantly buying, you can share the cost of holding the fund equally. It should be noted that if an investor makes a fixed investment in the process of fund rising, it will not reduce its position cost, but will increase its position cost; If investors make a fixed investment in the process of fund decline, it will reduce their position cost.

For example, when the net value of the fund is 1 yuan, investors start to make fixed investment, and the fixed investment amount is 1 1,000 yuan; When the net value of the fund is 0.8 yuan, they make a second fixed investment of 1 1,000 yuan; When the net value of the fund was 0.5 yuan, they made a fixed investment of 1 1,000 yuan for the third time. The cost price of investors' positions = 3000/(1000+1000/0.8+1000/0.5) = 0.706, which is lower than the initial fixed investment.

Generally speaking, it is best for investors to make a fixed investment when the fund falls.