A class in a family of multi-class mutual funds. This class is characterized by a back-end load structure that is paid only when the fund is sold.

Class B funds will generally have higher management expense ratios compared to front load funds within the same family. Fund companies attempt to increase their profits while the rear load is effective because it will normally decrease in value with time until no load is charged whatsoever.

Not all fund companies follow this class structure, but it is the prominent method of distinction.