share. A representation of ownership in a company or investment fund. Also a synonym for stock. share classes. Some mutual funds offer investors different types of shares known as classes (e.g., Class A, institutional shares). Each class will invest in the same portfolio of securities and will have the same investment objectives and policies, but each class will have different shareholder services and/or distribution arrangements with different fees and expenses and, therefore, different performance results. A multiclass structure offers investors the ability to select a fee and expense structure that is most appropriate for their investment goals (including the time that they expect to remain invested in the fund).