A money market mutual fund is a type of fixed income mutual fund that invests in debt securities characterized by their short maturities and minimal credit risk. Money market mutual funds are among the lowest-volatility types of investments. Income generated by a money market fund can be either taxable or tax-exempt, depending on the types of securities in which the fund invests.
The Money Market enables the commercial banks to use their excess reserves in profitable investment. The main objective of the commercial banks is to earn income from its reserves as well as maintain liquidity to meet the uncertain cash demand of the depositors. In the money market, the excess reserves of the commercial banks are invested in near-money assets (e.g., short-term bills of exchange), which are easily converted into cash. Thus, commercial banks earn profits without sacrificing liquidity.