Unless otherwise noted, the opinions provided are those of the speaker or author and not necessarily those of Fidelity Investments or its affiliates. Related Terms Mutual Fund Definition A mutual fund is a type of investment vehicle consisting of a portfolio of stocks, bonds, or other securities, which is overseen by a professional money manager. Furthermore, if you invest in «dividend aristocrats,» those companies that have been increasing dividends for 25 consecutive years, you can be virtually certain that these companies will up the yearly payout while bond payouts remain the same. Stock portfolios that include 12, 18 or even 30 stocks can eliminate most, if not all, unsystematic risk, according to some financial experts. Your Money.