The fund principal refers to the funds that investors buy into the fund, that is, the investor's principal, and the fund income refers to the profits generated by the funds that investors buy. Fund income = (current net value-net value at the time of purchase) * fund share handling fee.

Fund income is determined by the investment target. For example, stock funds mainly invest in a basket of stocks, and the rise and fall of the fund is determined by this basket of stocks. Invested stocks go up, funds go up, investors get profits, invested stocks go down, and funds go down, which leads to investors' losses.