The money market mutual fund portfolio is comprised of short-term (less than one year) securities representing high-quality, liquid debt and monetary instruments, for example, bank certificates of deposits, bank time deposits, commercial paper etc. The maturity of these funds on an average is 90 days. Investors who want to invest their short term money in extremely low but stable returns over a short period of time invest in these funds. These funds are also one of the best options for those investors who would like to balance their risk ratio by investing in a low risk low return fund. These funds will generally endeavour to deliver marginally higher returns as compared to a fixed deposit on a post-tax basis.