are available in the an- nual reports prepared by Wiesenberger Investment Companies Services or in Morningstars Mutual Fund Sourcebook, which can be found in many academic and public libraries. You should be aware of four general classes of fees.   Front-End Load A front-end load is a commission or sales charge paid when you pur- chase the shares. These charges, which are used primarily to pay the brokers who sell the funds, may not exceed 8.5%, but in practice they are rarely higher than 6%. Low-load funds have loads that range up to 3% of invested funds. No-load funds have no front-end sales charges. Loads effectively reduce the amount of money invested. For example, each $1,000 paid for a fund with an 8.5% load results in a sales charge of $85 and fund investment of only $915. You need cumulative returns of 9.3% of your net investment (85/915 = .093) just to break even.   Back-End Load A back-end load is a redemption, or "exit," fee incurred when you sell your shares. Typically, funds that impose back-end loads start them at 5% or 6% and reduce them by 1 percentage point for every year the funds are left invested. Thus an exit fee that starts at 6% would fall to 4% by the start of your third year. These charges are known more formally as "contingent deferred sales charges."   Operating Expenses Operating expenses are the costs incurred by the mutual fund in operating the portfolio, including administrative expenses and advisory fees paid to the investment manager. These expenses, usually expressed as a percentage of total assets un- der management, may range from 0.2% to 2%. Shareholders do not receive an explicit bill for these operating expenses; however, the expenses periodically are deducted from the assets of the fund. Shareholders pay for these expenses through the reduced value of the portfolio.   12b-1 Charges The Securities and Exchange Commission allows the managers of so- called 12b-1 funds to use fund assets to pay for distribution costs such as advertising, pro- motional literature including annual reports and prospectuses, and, most important, commissions paid to brokers who sell the fund to investors. These 12b-1 fees are named af- ter the SEC rule that permits use of these plans. Funds may use 12b-1 charges instead of, or in addition to, front-end loads to generate the fees with which to pay brokers. As with oper- ating expenses, investors are not explicitly billed for 12b-1 charges. Instead, the fees are de- ducted from the assets of the fund. Therefore, 12b-1 fees (if any) must be added to operating expenses to obtain the true annual expense ratio of the fund. The SEC now requires that all funds include in the prospectus a consolidated expense table that summarizes all relevant fees. The 12b-1 fees are limited to 1% of a funds average net assets per year.1 A recent innovation in the fee structure of mutual funds is the creation of different "classes"; they represent ownership in the same portfolio of securities but impose different combinations of fees. For example, Class A shares typically are sold with front-end loads of between 4% and 5%. Class B shares impose 12b-1 charges and back-end