There are several kinds of funds, namely, money funds, mixed funds and stock funds. Except for the money fund, the other two funds are changeable and may lose money. According to your present situation, your forty thousand dollars must have bought some hybrid funds. If the fund you buy doesn't perform well, you will lose money, which is why your money is less.

If you want to stabilize your income, it is better to switch to a low-risk money fund.