An extra fee charged by some mutual funds to cover promotion, distributions, marketing expenses, and sometimes commissions to brokers. A genuine no-load fund does not have Rule 12b-1 fees, although some funds calling themselves "no-load" do have Rule 12b-1 fees (as do some load funds). Rule 12b-1 fee information is disclosed in a fund's prospectus, is included in the stated expense ratio, and is usually less than 1%. also called 12b-1 fee.