If you plan to invest in a long-term fund and your income source is relatively stable, you may wish to invest in the fund by stages, that is, invest a fixed amount of money every month (or regularly) regardless of market conditions. When the market rises, the net value of the fund is high, and the number of units you buy is small; When the market falls, the net value of the fund is low and more units are bought. In this long term, the average cost of purchased fund shares will be lower than the average market price, which is the so-called average cost method. The function of the average cost method can be brought into play mainly because when the stock market falls, investors passively invest and buy more units. As long as you believe that the long-term performance of the stock market should be an upward trend, buying low-cost stocks at the low end of the stock market will certainly bring rich profits. Just consult and buy a fund and go to the bank.