What type of fee does a mutual fund sponsor often reduce the longer an investor...

Back-end load funds often have a decreasing redemption fee (deferred sales charge) schedule, which reduces the longer the investor holds the fund. The feedback from the document states:

"Fund sponsors use a decreasing redemption fee (deferred sales charges) schedule to recover their costs from investors who opt out of the fund early. In most cases, redemption fees on a back-end load fund decrease the longer the investor holds the fund."