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A mutual fund is a professionally managed firm of collective investments that collects money from many investors and puts it in stocks, bonds, short-term money market instruments, and/or other securities. The fund manager, also known as portfolio manager, trades the fund's underlying securities, realizing capital gains or losses and passing any proceeds to the individual investors. Currently, the worldwide value of all mutual funds totals more than $26 trillion. 
Since 1940, there have been three basic types of mutual fund investment companies in the United States. Similar funds also operate in Canada. However, in the rest of the world, mutual fund is used as a generic term for various types of collective investment vehicles, such as unit trusts, open-ended investment companies (OEICs), and unitized insurance funds.