What is a mutual fund? It's an investment company! It is an indirect investment where the mutual fund portfolio managers choose the stocks or bonds or other investment choices for us. Mutual funds are...What is a mutual fund? It's an investment company! It is an indirect investment where the mutual fund portfolio managers choose the stocks or bonds or other investment choices for us. Mutual funds are truly investments for the masses. With mutual funds, investors get two important benefits, professional money management and diversification.