Convert

Some funds provide automatic conversions from one class to another. This means that you will begin to pay the fees and expenses charged by the class to which your shares have converted. Typically, the class before conversion has higher annual expenses than the class after conversion.

Often, a fund's Class B shares convert to Class A shares after a period of time. The mutual fund's prospectus will tell you whether the class you are evaluating converts to another class after a period of time. The fund's profile also may tell you whether the class you are evaluating converts to another class after a period of time in a footnote to the fee and expense table.

http://www.sec.gov/investor/tools/mfcc/convert-help.htm