Monetary fund is an open-end fund that collects idle social funds, is operated by fund managers and kept by fund custodians. It specializes in investing in risk-free money market instruments, which is different from other types of open-end funds. It has the characteristics of high security, high liquidity, stable income and "quasi-savings". The assets of the Fund are mainly invested in short-term monetary instruments (generally within one year, with an average maturity of 120 days), such as government bonds, central bank bills, commercial bills, bank time deposit certificates, government short-term bonds, corporate bonds (with high credit rating), interbank deposits and other short-term securities.

In fact, the investment scope of these money market funds are all varieties with high safety factor and stable income, so for many enterprises and individuals who want to avoid the risks in the securities market, money market funds are a natural haven, which can not only obtain the income higher than the interest of bank deposits, but also ensure the safety of the principal.

The net asset value of money market funds is usually maintained at 1 yuan. Although this "1 yuan net value" is not a mandatory requirement or a guarantee requirement, due to the stability of the short-term securities income invested by it, the fund manager can maintain the unit net value at the level of 1 yuan for a long time, and the fluctuation is only the dividend level paid by the fund.