As filed with the Securities and Exchange Commission on April 30, 2025

Securities Act File No. 333-81209

Investment Company Act File No. 811-09397

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

THE GABELLI UTILITIES FUND

(Exact Name of Registrant as Specified in Charter)

One Corporate Center, Rye, New York 10580-1422

(Address of Principal Executive Offices)

Registrant’s Telephone Number, including Area Code: 1-800-422-3554

John C. Ball

Gabelli Funds, LLC

One Corporate Center

Rye, New York 10580-1422

(Name and Address of Agent for Service)

Copies to:

It is proposed that this filing will become effective:

If appropriate, check the following box:

SUMMARY OF THE FUND

Investment Objective

Fees and Expenses of the Fund:

Expense Example

Portfolio Turnover

Principal Investment Strategies

Principal Risks

Performance

THE GABELLI UTILITIES FUND 
(Total Returns for Class AAA Shares for the Years Ended December 31)

Management

The Adviser. Gabelli Funds, LLC

The Portfolio Managers. Mr. Mario J. Gabelli, CFA, Chief Investment Officer — Value Portfolios of the Adviser, has served as portfolio manager of the Fund since its inception on August 31, 1999. Mr. Timothy M. Winter, CFA, has served as an associate portfolio manager of the Fund since May 2018. Mr. Justin Bergner has served as associate portfolio managers of the Fund since July 1, 2021. Mr. Robert D. Leininger has served as a portfolio manager of the Fund since August 31, 2023. Mr. Ashish Sinha has served as a portfolio manager of the Fund since October 23, 2023.

Purchase and Sale of Fund Shares

The minimum initial investment for Class AAA, Class A, and Class C shares is $1,000 ($250 for IRAs or Coverdell Education Savings Plans). There is no minimum initial investment for Class AAA, Class A, and Class C shares in an automatic monthly investment plan. Class I shares are available to investors with a minimum investment of $50,000 when purchasing the shares directly through G.distributors, LLC, the Fund’s distributor (“G.distributors” or the “Distributor”), or investors purchasing Class I shares through brokers or financial intermediaries that have entered into selling agreements with the Distributor specifically with respect to Class I shares, and which have different minimum investment amounts. If you transact in Class I shares through a broker or financial intermediary, you may be required to pay a commission and/or other forms of compensation to the broker or financial intermediary. The Distributor reserves the right to waive or change minimum investment amounts. There is no minimum for subsequent investments.

You can purchase or redeem shares of the Fund on any day the New York Stock Exchange (“NYSE”) is open for trading (a “Business Day”). You may purchase or redeem Fund shares by written request via mail (The Gabelli Funds, P.O. Box 219204, Kansas City, MO 64121-9204), personal or overnight delivery (The Gabelli Funds, c/o SS&C Global Investor & Distribution Solutions, Inc., 801 Pennsylvania Avenue, Suite 219204, Kansas City, MO 64105-1307), Internet, bank wire, or Automated Clearing House (“ACH”) system. You may also purchase Fund shares by telephone at 800-GABELLI (800-422-3554), if you have an existing account with banking instructions on file.

Fund shares can also be purchased or sold through registered broker-dealers or financial intermediaries that have entered into appropriate selling agreements with the Distributor. The broker-dealer or other financial intermediary will transmit these transaction orders to the Fund on your behalf and send you confirmation of your transactions and periodic account statements showing your investments in the Fund.

Tax Information

The Fund expects that distributions will generally be taxable as ordinary income or long term capital gains, unless you are investing through a tax deferred arrangement, such as a 401(k) plan or an IRA.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of the Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

INVESTMENT OBJECTIVE, INVESTMENT STRATEGIES, AND RELATED RISKS

The Fund’s investment objective is to seek to provide a high level of total return through a combination of capital appreciation and current income. The investment objective of the Fund may not be changed without shareholder approval.

Under normal circumstances, the Fund invests at least 80% of its net assets in securities of Utility Companies that the Adviser believes have the potential to provide either capital appreciation or current income (the “80% Investment Policy”). The 80% Investment Policy may be changed by the Board of Trustees (the “Board”) without shareholder approval. Shareholders will, however, receive at least sixty days prior notice of any change in this policy. Generally, Utility Companies generate relatively predictable streams of revenue and income, and in the view of the Adviser, are likely to pay dividends. However, the Fund focuses on those companies in this industry whose common stocks may be undervalued and thus have the potential for capital appreciation. The Fund’s performance is expected to reflect conditions affecting the utilities industry. This industry is sensitive to factors such as interest rates, local and national government regulations, the price and availability of materials used in the particular utility, environmental protection or energy conservation regulations, the level of demand for services, and the risks associated with constructing and operating certain kinds of facilities, such as nuclear power facilities. These factors may change rapidly. The Adviser emphasizes quality in selecting utility investments, and looks for companies that have proven dividend records and sound financial structures. Believing that the industry is under consolidation due to changes in regulation, the Fund seeks to position itself to take advantage of trends in consolidation.

Undervaluation of the stock of a Utility Company with good intermediate and longer term fundamentals can result from a variety of factors, such as a lack of investor recognition of:

Actual events that may lead to a significant increase in the value of a company’s securities include:

In selecting investments, the Adviser will consider factors such as: (i) the market price of the issuer’s common stock, earnings expectations, earnings and price histories, balance sheet characteristics, perceived management skills, and the conditions affecting the industry in which the issuer practices; (ii) the level of interest rates, local and national government regulations, the price and availability of materials used in the particular utility, environmental protection or energy conservation regulations, the level of demand for services, and the risks associated with constructing and operating certain kinds of facilities such as nuclear power facilities; (iii) the potential for capital appreciation of the stock; (iv) the dividend income generated by the stock; (v) the prices of the stock relative to other comparable stocks; and (vi) the diversification of the portfolio of the Fund as to issuers. The Adviser will also consider changes in economic and political outlooks as well as individual corporate developments. The Adviser will sell any Fund investments that lose their perceived value relative to other investments in the judgment of the portfolio management team.

The Fund’s assets will be invested primarily in a broad range of readily marketable dividend-paying common stocks in the utilities industry. Although many of the common stocks will pay above average dividends, the Fund will buy stock of those companies whose securities have the potential for their prices to increase, providing either capital appreciation or current income for the Fund. The value of common stocks will fluctuate due to many factors, including the past and predicted earnings of the issuer, the quality of the issuer’s management, general market conditions, the forecasts for the issuer’s industry, and the value of the issuer’s assets. Holders of common stocks only have rights to the value in the company after all issuer debts have been paid, and they could lose their entire investment in a company that encounters financial difficulty. The Fund may also invest in MLPs.

The Fund’s policy of concentration in companies in the utilities industry is a fundamental policy of the Fund. Fundamental policies may not be changed without the authorization of a vote of a majority (as defined in the Investment Company Act of 1940, as amended (the “1940 Act”)) of the Fund’s outstanding shares.

The Fund may also use the following investment techniques:

The Fund may also engage in other investment practices in order to achieve its investment objective. These are discussed in the Statement of Additional Information (“SAI”), which may be obtained by calling 800-GABELLI (800-422-3554), your financial intermediary, or free of charge through the Fund’s website at www.gabelli.com.

Investing in the Fund involves the following risks:

Utility Companies may continue to be subject to attempts to gain unauthorized access to or through their operating systems and physical attacks on industry and company infrastructure, property and equipment. Any physical damage, system failure, cybersecurity breach, ransomware attack, system disruption or other material harm could interrupt or delay operations and impact a Utility Company’s ability to manage its operations and report financial performance, which could have a materially adverse effect on existing and future business. These and other developments may adversely impact the value of the Fund’s investments in Utility Companies.

The rating agencies look closely at the business profile of utilities. Ratings for companies are expected to be affected to a greater extent in the future by how their asset base is utilized. Electric utility companies that focus more on the generation of electricity may be assigned less favorable ratings as this business is expected to be competitive and the least regulated. On the other hand, companies that focus on transmission and distribution, which is expected to be the least competitive and the more regulated part of the business, may see higher ratings given the greater predictability of cash flow.

The United Kingdom ceased to be a member of the European Union (the “EU”) on January 31, 2020 (“Brexit”). A Trade and Cooperation Agreement between the EU and the United Kingdom (the “TCA”) took effect on May 1, 2021, and now governs the relationship between the EU and the United Kingdom. While the TCA regulates a number of important areas, significant parts of the United Kingdom economy are not addressed in detail by the TCA, including in particular the services sector, which represents the largest component of the United Kingdom’s economy. As such, there remains uncertainty as to the scope, nature and terms of the relationship between the United Kingdom and the EU and the effect and implications of the TCA. Brexit may have a negative impact on the economy and currency of the United Kingdom and EU as a result of anticipated, perceived or actual changes to the United Kingdom’s economic and political relations with the EU. Brexit may also have a destabilizing impact on the EU to the extent other member states similarly seek to withdraw from the union. Any further exits of member states from the EU, or the possibility of such exits, would likely cause additional market disruption

globally and introduce new legal and regulatory uncertainties. Any or all of these challenges may affect the value of a Fund’s investments that are economically tied to the United Kingdom or the EU, and could have an adverse impact on a Fund’s performance.

Portfolio Holdings. A description of the Fund’s policies and procedures with respect to the disclosure of the Fund’s portfolio securities is available in the SAI, which may be obtained by calling 800-GABELLI (800-422-3554), your financial intermediary, or free of charge through the Fund’s website at www.gabelli.com.

ReFlow Liquidity Program. The Fund may participate from time to time in a program offered by ReFlow Fund, LLC (“ReFlow”). Pursuant to the program and subject to certain conditions, ReFlow provides participating mutual funds with a source of cash to meet net shareholder redemptions by purchasing fund shares at net asset value in an amount up to the value of the net shares redeemed. Following purchases

of fund shares, ReFlow then redeems those shares when a fund experiences net sales, at the end of a maximum holding period determined by ReFlow, or at other times at a fund’s or ReFlow’s discretion. While ReFlow holds a fund’s shares, it has the same rights and privileges with respect to those shares as any other shareholder. However, investments in the Fund by ReFlow are exempt from the Funds’ 2.00% short term trading fee policy as described in this Prospectus.

In the event a Fund uses the ReFlow program, such Fund will pay a fee to ReFlow each time ReFlow purchases Fund shares, calculated by applying to the purchase amount a fee rate determined through an automated daily auction among participating mutual funds seeking liquidity that day. The current minimum fee rate is 0.14% of the value of a Fund’s shares purchased by ReFlow. ReFlow’s purchases of Fund shares through the liquidity program are made on an investment-blind basis without regard to a Fund’s investment objective, policies or anticipated performance. In accordance with federal securities laws, ReFlow is prohibited from acquiring more than 3% of the outstanding voting securities of a Fund. When ReFlow redeems all or part of a position in a Fund, such Fund may pay all or a portion of such redemption in kind. Each Fund expects that in-kind redemptions will comprise a significant portion of redemptions paid to ReFlow.

MANAGEMENT OF THE FUND

The Adviser. Gabelli Funds, LLC, with its principal offices located at One Corporate Center, Rye, New York 10580-1422, is a New York limited liability company that serves as investment adviser to the Fund. The Adviser makes investment decisions for the Fund and continuously reviews and administers the Fund’s investment program and manages the Fund’s operations under the general supervision of the Fund’s Board. The Adviser also manages several other open-end and closed-end investment companies in the Gabelli family of funds (“Gabelli Fund Complex” or “Fund Complex”). The Adviser is a wholly owned subsidiary of GAMCO Investors, Inc. (“GAMI”), a publicly held company listed on the OTCQX.

As compensation for its services and related expenses borne by the Adviser for the fiscal year ended December 31, 2024, the Fund paid the Adviser a fee computed daily and payable monthly equal to 1.00% of the value of the Fund’s average daily net assets.

The Fund’s Form N-CSR for the period ended June 30, 2024 contains a discussion of the basis of the Board’s determination to continue the investment advisory agreement.

The Portfolio Managers. Mr. Mario J. Gabelli, CFA, is primarily responsible for the day to day investment management of the Fund. Mr. Gabelli is Chairman and Co-Chief Executive Officer of GAMI and Associated Capital Group, Inc.; Chief Investment Officer — Value Portfolios of GAMI, Gabelli Funds, LLC, and GAMCO Asset Management, Inc., another wholly owned subsidiary of GAMI; Chief Executive Officer and Chief Investment Officer of GGCP, Inc.; and an officer or director of other companies affiliated with GAMI. The Adviser relies to a considerable extent on the expertise of Mr. Gabelli, who may be difficult to replace in the event of his death, disability, or resignation.

Mr. Timothy M. Winter, CFA, has served as portfolio manager of the Fund since May 2018. He joined Gabelli & Company in April of 2009 and covers the utility industry. He has over 20 years’ experience as an equity research analyst covering this industry, including the years 1992-2007 at AG Edwards from where he received industry recognition as a 3 time Wall Street Journal All-Star and was a senior member of the

Institutional Investor (I.I.) #1 ranked Electric Utility Team for the years 2001, 2002, 2003, 2004 and 2005. He was most recently recognized in the 2017 Thomson Reuters US Analyst Awards as a “Top Stock Picker” in the gas utility industry. Mr. Winter received his BA in Economics in 1991 from Rollins College and MBA in Finance from Notre Dame in 1992.

Mr. Justin Bergner joined the portfolio management team as an associate portfolio manager effective July 1, 2021. Mr. Bergner has been a research analyst at GAMCO Investors, Inc. since 2013. Mr. Bergner graduated cum laude from Yale University with a BA in Economics & Mathematics and received an MBA in Finance and Accounting from the Wharton School at the University of Pennsylvania.

Mr. Robert D. Leininger, CFA, joined the portfolio management team effective August 31, 2023. He joined GAMI in 1993 as a security analyst. Mr. Leininger moved to Rorer Asset Management LLC in Philadelphia in 1997, where he was a partner in the firm and member of the investment policy committee. In August 2009, he joined Copeland Capital Management as a partner and portfolio manager before rejoining GAMI in 2010 where he currently serves as a portfolio manager for the Adviser and on GAMCO’s institutional and high net worth separate accounts team. He is a member of the Financial Analyst Society of Philadelphia. Mr. Leininger is a magna cum laude graduate of Amherst College with a degree in Economics and holds an MBA from the Wharton School at the University of Pennsylvania.

Mr. Ashish Sinha joined the portfolio management team effective October 23, 2023. He joined GAMCO UK in 2012 as a research analyst. Prior to joining the Firm, Mr. Sinha was a research analyst at Morgan Stanley in London for seven years and has covered European Technology, Mid-Caps and Business Services. He also worked in planning and strategy at Birla Sun Life Insurance in India. Currently Mr. Sinha is a portfolio manager of Gabelli Funds, LLC and an Assistant Vice President of GAMCO Asset Management UK. Mr. Sinha has a BSBA degree from the Institute of Management Studies and an MBA from the Indian Institute of Foreign Trade.

The Fund’s SAI provides additional information about the portfolio managers’ compensation, other accounts managed by them, and their ownership of securities, if any, in the Fund.

INDEX DESCRIPTIONS

The S&P 500 Utilities Index is an unmanaged market capitalization-weighted index consisting of the gas, electric, and telephone stocks that are included in the S&P 500 Index, a market capitalization-weighted index of common stocks. The index figures do not reflect any deduction for fees, expenses, or taxes. You cannot invest directly in the S&P 500 Utilities Index.

The Lipper Utility Fund Average reflects the average performance of mutual funds classified in this particular category.

CLASSES OF SHARES

Four classes of the Fund’s shares are offered in this prospectus — Class AAA shares, Class A shares, Class C shares, and Class I shares. The Fund is not designed for market timers; see the section entitled “Redemption of Shares.” Each class of shares has different costs associated with buying, selling, and holding Fund shares. Your broker or other financial professional can assist you in selecting which class of shares best meets your needs based on such factors as the size of your investments and the length of time you intend to hold your shares.

The minimum initial investment for Class AAA, Class A, and Class C shares is $1,000.

The Fund’s Class AAA shares are offered only to (1) clients of broker-dealers or other financial intermediaries (i) that charge such clients an ongoing fee for advisory, investment, consulting, or similar service or (ii) where the Distributor has entered into an agreement permitting the financial intermediary to offer Class AAA shares through its mutual fund supermarket network or platform, and (2) customers of the Distributor.

Class I shares are available to investors with a minimum investment of $50,000 and purchasing shares directly through the Distributor, or investors purchasing Class I shares through brokers or financial intermediaries that have entered into selling agreements with the Distributor specifically with respect to Class I shares. Such brokers or financial intermediaries may have different requirements as to the investment minimum. If you transact in Class I shares through a broker or financial intermediary, you may be required to pay a commission and/or other forms of compensation to the broker or financial intermediary.

The Distributor or its affiliates may, in their discretion, accept investments from purchasers that do not meet the qualification requirements.

There is no minimum for subsequent investments.

The table that follows summarizes the differences among the classes of shares.

In selecting a class of shares in which to invest, you should consider:

The following sections and Appendix A to this prospectus include important information about sales charges and sales charge reductions and waivers, and describe information or records you may need to provide to the Fund or your broker in order to be eligible for sales charge reductions and waivers. Intermediaries may have different policies and procedures regarding the availability of sales charge reductions and waivers; please refer to Appendix A to this prospectus, which describes all such intermediaries. Information about sales charges and sales charge reductions and waivers to the various classes of the Fund’s shares is also available free of charge and in a clear and prominent format on our website at www.gabelli.com. You should consider the information below as a guide only, as the decision on which share class is best for you depends on your individual needs and circumstances.

Sales Charge — Class A Shares. Unless you are eligible for a sales charge reduction or a waiver as set forth in Appendix A to this prospectus, the sales charge is imposed on Class A shares at the time of purchase in accordance with the following schedule. It is the purchaser’s responsibility to notify the Fund, the Distributor, or the purchaser’s financial intermediary at the time of purchase of any relationship or other facts qualifying the purchaser for sales charge reductions or waivers.

No sales charge is imposed on reinvestment of dividends and distributions if you selected that option in advance of the distributions.

Breakpoints or Volume Discounts

The Fund offers you the benefit of discounts on the sales charges that apply to purchases of Class A shares in certain circumstances. These discounts, which are also known as breakpoints, can reduce or, in some instances, eliminate the initial sales charges that would otherwise apply to your Class A shares investment. Mutual funds are not required to offer breakpoints and different mutual fund groups may offer different types of breakpoints.

Breakpoints or volume discounts allow larger investments in Class A shares to be charged lower sales charges. If you invest $50,000 or more in Class A shares of the Fund, then you are eligible for a reduced

sales charge. Initial sales charges are eliminated completely for purchases of $1,000,000 or more, although a 1% CDSC may apply if shares are redeemed up to and including the last day of the eighteenth month after purchase.

Sales Charge Reductions and Waivers — Class A Shares

Reduced sales charges are available to (1) investors who are eligible to combine their purchases of Class A shares to receive volume discounts and (2) investors who sign a Letter of Intent (“Letter”) agreeing to make purchases over time. Certain types of investors, as set forth below, are eligible for sales charge waivers.

Class A shares may be available for purchase by clients of certain financial intermediaries without the application of a front-end sales load, as described in Appendix A to the prospectus.

You may qualify for a reduced sales charge, or a waiver of sales charges, on purchases of Class A shares. The requirements are described in the following paragraphs. To receive a reduction that you qualify for, you may have to provide additional information to your broker or other service agent. For more information about sales charge discounts and waivers, consult with your broker or other service provider.

Volume Discounts/Rights of Accumulation. In order to determine whether you qualify for a volume discount under the foregoing sales charge schedule, you may combine your new investment and your existing investments in Class A shares with those of your immediate family (spouse and children under age 21), your and their IRAs, and other employee benefit plans and trusts and other fiduciary accounts for your and their benefit. You may also include Class A shares of any other open-end investment company managed by the Adviser or its affiliates that are held in any of the foregoing accounts. The Fund uses the current net asset value per share (“NAV”) of these holdings when combining them with your new and existing investments for purposes of determining whether you qualify for a volume discount.

Letter of Intent. If you initially invest at least $1,000 in Class A shares of the Fund and submit a Letter to your financial intermediary or the Distributor, you may make purchases of Class A shares of the Fund during a thirteen-month period at the reduced sales charge rates applicable to the aggregate amount of the intended purchases stated in the Letter. The Letter may apply to purchases made up to ninety days before the date of the Letter. If you fail to invest the total amount stated in the Letter, the Fund will retroactively collect the sales charge otherwise applicable by redeeming shares in your account at their then current NAV. For more information on the Letter, call your broker.

Required Shareholder Information and Records. In order for you to take advantage of sales charge reductions, you or your broker must notify the Fund that you qualify for a reduction. Without notification, the Fund is unable to ensure that the reduction is applied to your account. You may have to provide information or records to your broker or the Fund to verify eligibility for breakpoint privileges or other sales charge waivers. This may include information or records, including account statements, regarding shares of the Fund or shares of any other open-end investment company managed by the Adviser or its affiliates held in:

You should therefore keep copies of these types of records.

Investors Eligible for Sales Charge Waivers. Class A shares of the Fund may be offered without a sales charge to: (1) employees of the Distributor and its affiliates, The Bank of New York Mellon Corporation, SS&C Global & Distribution Solutions, Inc. (“SS&C GIDS” or the “Transfer Agent”), State Street Bank and Trust Company, (“State Street”), BNY Mellon Investment Servicing (US) Inc., and Soliciting Broker-Dealers, employee benefit plans for those employees and their spouses and minor children of such employees when orders on their behalf are placed by such employees (the minimum initial investment for such purchases is $500); (2) the Adviser, its affiliates and their officers, directors, trustees, general partners, and employees of other investment companies managed by the Adviser, employee benefit plans for such persons and their immediate family when orders on their behalf are placed by such persons (with no required minimum initial investment) — the term “immediate family” for this purpose refers to a person’s spouse, children and grandchildren (adopted or natural), parents, grandparents, siblings, a spouse’s siblings, a sibling’s spouse, and a sibling’s children; (3) any other investment company in connection with the combination of such company with the Fund by merger, acquisition of assets, or otherwise; (4) shareholders who have redeemed shares in the Fund and who wish to reinvest in the Fund, provided the reinvestment is made within ninety days of the redemption; (5) employee benefit plans; (6) any unit investment trusts registered under the 1940 Act which have shares of the Fund as a principal investment; (7) investment advisory clients of GAMCO Asset Management, Inc. and their immediate families; (8) financial institutions purchasing Class A shares of the Fund for clients participating in a fee based asset allocation program or wrap fee program; and (9) investment advisers or financial planners who place trades for their own accounts or the accounts of their clients and who charge a management, consulting, or other fee for their services; and clients of such investment advisers or financial planners who place trades for their own accounts if the accounts are linked to the master account of such investment adviser or financial planner on the books and records of a broker or financial intermediary.

Additional categories of sales charge reductions and waivers are also set out in Appendix A to this prospectus.

Investors who qualify under any of the categories described above or those set out in the Appendix A to this prospectus should contact their broker or financial intermediary. Some of these investors may also qualify to invest in Class I shares.

Contingent Deferred Sales Charges

You will pay a CDSC when you redeem:

The CDSCs payable upon redemption of Class A shares in the circumstances described above are 1.00% for investments of $1 million but less than $2 million, 0.50% for investments of $2 million but less than $5 million, and 0.25% for investments of $5 million or more. The CDSC payable upon redemption of Class C shares in the circumstances described above is 1.00%. In each case, the CDSC is based on the NAV at the time of your investment or the NAV at the time of redemption, whichever is lower.

The Distributor pays sales commissions of up to 1.00% of the purchase price of Class C shares of the Fund at the time of sale to brokers and financial intermediaries that initiate and are responsible for purchases of such Class C shares of the Fund.

You will not pay a CDSC to the extent that the value of the redeemed shares represents reinvestment of distributions or capital appreciation of shares redeemed. When you redeem shares, we will assume that you are first redeeming shares representing reinvestment of dividends and capital gain distributions, then any appreciation on shares redeemed, and then any remaining shares held by you for the longest period of time. We will calculate the holding period of shares acquired through an exchange of shares of another fund from the date you acquired the original shares of the other fund. The time you hold shares in the Gabelli money market fund, however, will not count for purposes of calculating the applicable CDSC.

We will waive the CDSC payable upon redemptions of shares for:

The CDSC may be waived if you purchase your shares through intermediaries identified in Appendix A to this prospectus.

Rule 12b-1 Plan. The Fund has adopted distribution plans under Rule 12b-1 for Class AAA, Class A and Class C shares of the Fund (“Plans” or each, a “Plan”). Under these Plans, the Fund may use its assets to finance activities relating to the sale of its Class AAA, Class A and Class C shares and the provision of certain shareholder services. To the extent any activity is one that the Fund may finance without a distribution plan, the Fund may also make payments to compensate for such activities outside a Plan and not be subject to its limitations.

The Class AAA and Class A Plans authorize payments by the Fund at an annual rate of 0.25% of its average daily net assets attributable to Class AAA and Class A shares to finance distribution of its Class AAA and Class A shares or pay shareholder service fees. The Class C Plan authorizes payments by the Fund at an annual rate of 0.75% of its average daily net assets attributable to Class C shares to finance distribution of its Class C shares and 0.25% for shareholder service fees.

Because the Rule 12b-1 fees are higher for Class C shares than for Class AAA or Class A shares, Class C shares will have higher annual expenses. Because Rule 12b-1 fees are paid out of the Fund’s assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of sales charges. Due to the payment of Rule 12b-1 fees, long term shareholders may indirectly pay more than the equivalent of the maximum permitted front-end sales charge.

Redemption Fee. Generally, if you sell or exchange your shares within seven days or less after the purchase date, you will be charged a redemption fee of 2.00% of the total redemption amount which is payable to the Fund. See “Redemption of Shares” herein.

PURCHASE OF SHARES

You can purchase the Fund’s shares on any Business Day.

You can obtain a subscription order form by calling 800-GABELLI (800-422-3554). Checks made payable to a third party and endorsed by the shareholder are not acceptable. For additional investments, send a check to the above address with a note stating your exact name and account number, the name of the fund(s), and class of shares you wish to purchase.

State Street Bank and Trust Company
225 Franklin Street, Boston, MA 02110
ABA #011-0000-28 REF DDA #99046187
Re: The Gabelli Utilities Fund
Account # __________________
Account of [Registered Owners]

If you are making an initial purchase, you should also complete and mail a subscription order form to the address shown under “By Mail.” Note that banks may charge fees for wiring funds, although the Fund’s transfer agent, SS&C GIDS, will not charge you for receiving wire transfers.

You may purchase shares directly through registered broker-dealers or other financial intermediaries that have entered into appropriate selling agreements with the Distributor.

Your broker-dealer or financial intermediary can obtain a subscription order form by calling 800-GABELLI (800-422-3554). The broker-dealer or other financial intermediary will transmit a purchase order and payment to SS&C GIDS on your behalf. Broker-dealers or other financial intermediaries may send you confirmations of your transactions and periodic account statements showing your investments in the Fund.

Share Price. The Fund sells its shares based on the NAV next determined after the time as of which the Fund receives your completed subscription order form but does not issue the shares to you until it receives full payment, subject to a front-end sales charge in the case of Class A shares. See “Pricing of Fund Shares” herein for a description of the calculation of the NAV, as described under “Classes of Shares — Sales Charge — Class A Shares.”

Minimum Investments. The minimum initial investment for Class AAA, Class A, and Class C shares is $1,000 ($250 for IRAs or Coverdell Education Savings Plans). The minimum initial investment for Class I shares is $50,000 for investors purchasing Class I shares directly through the Distributor. Investors who wish to purchase Class I shares through brokers or financial intermediaries that have entered into selling agreements with the Distributor specifically with respect to Class I shares should consult their broker or financial intermediary with respect to any minimum investment amount required for their account. The Distributor or its affiliates may, in their discretion, waive the minimum investment requirement under certain circumstances. There is no minimum for subsequent investments. Broker-dealers and financial intermediaries may have different minimum investment requirements.

General. SS&C GIDS will not issue share certificates unless you request them. The Fund reserves the right to (i) reject any purchase order if, in the opinion of the Fund’s management, it is in the Fund’s best interest to do so, (ii) suspend the offering of shares for any period of time, and (iii) waive the Fund’s minimum purchase requirements. Except for differences attributable to these arrangements, the shares of all classes are substantially the same.

Customer Identification Program. Federal law requires the Fund to obtain, verify, and record identifying information, which may include the name, residential or business address, date of birth (for an individual), social security or taxpayer identification number, or other identifying information, for each investor who opens or reopens an account with the Fund. Applications without the required information may be rejected or placed on hold until the Fund verifies the account holder’s identity.

Third Party Arrangements. In addition to, or in lieu of amounts received by broker-dealers or other financial intermediaries as reallowances of a portion of sales commissions, the Adviser and its affiliates may utilize a portion of their assets, which may include revenues received under the Plans, to pay all or a portion of the charges of various programs that make shares of the Fund available to their customers. These payments, sometimes referred to as “revenue sharing,” do not change the price paid by investors to purchase the Fund’s shares or the amount the Fund receives as proceeds from such sales. Revenue sharing payments may be made to broker-dealers and other financial intermediaries that provide services to the Fund or to shareholders in the Fund, including (without limitation) the following programs: shareholder servicing to Fund shareholders, transaction processing, sub-accounting services, marketing support, access to sales meetings, sales representatives, and management representatives of the broker- dealer or other financial intermediaries. Revenue sharing payments may also be made to broker-dealers and other financial intermediaries for inclusion of the Fund on a sales list, including a preferred or select sales list, and in other sales programs. These payments take a variety of forms, including (without limitation) compensation for sales, “trail” fees for shareholder servicing and maintenance of shareholder accounts, and finders’ fees that vary depending on the share class and the dollar amount of shares sold. Revenue sharing payments may be structured: (i) as a percentage of sales; (ii) as a percentage of net assets; and/or (iii) as a fixed dollar amount.

The Adviser may also provide non-cash compensation to broker-dealers or other financial intermediaries in accordance with applicable rules of the Financial Industry Regulatory Authority, Inc. (“FINRA”), such as the reimbursement of travel, lodging, and meal expenses incurred in connection with attendance at educational and due diligence meetings or seminars by qualified registered representatives of those firms and, in certain

cases, their families; meeting fees; certain entertainment; advertising or other promotional expenses; or other permitted expenses as determined in accordance with applicable FINRA rules. In certain cases these other payments could be significant.

Subject to tax limitations and approval by the Board, the Fund may also make payments to third parties out of its own assets (other than Rule 12b-1 payments) for a portion of the charges for those programs that generally represent savings of expenses experienced by the Fund resulting from shareholders investing in the Fund through such programs rather than investing directly in the Fund.

The Adviser negotiates the level of payments described above to any particular broker-dealer or other financial intermediary. Currently, such payments (expressed as a percentage of net assets) range from 0.10% to 0.40% per year of the average daily net assets of the Fund attributable to the particular firm depending on the nature and level of services and other factors. In the case of Class I shares, the Fund may not make any payments for distribution related services.

In addition, in certain cases, broker-dealers or other financial intermediaries, may have agreements pursuant to which shares of the Fund owned by their clients are held of record on the books of the Fund in omnibus accounts maintained by each intermediary, and the intermediaries provide those Fund shareholders with sub-administration and sub-transfer agency services. Pursuant to the Fund’s transfer agency agreement, the Fund pays the transfer agent a fee for each shareholder account. As a result, the use of one omnibus account for multiple beneficial shareholders can create a cost savings to the Fund. The Board may, from time to time, authorize the Fund to pay for a portion of the fees charged by these intermediaries if (i) a cost savings to the Fund can be demonstrated and (ii) the omnibus account of the intermediary has net assets in the Fund in excess of $10 million. In these cases, the Board may authorize the Fund to pay a portion of the fees to the intermediary in an amount no greater than the lower of the transfer agency cost savings relating to the particular omnibus account or 0.10% of the average daily net assets of that omnibus account. These payments compensate these intermediaries for the provision of sub-administration and sub-transfer agency services associated with their clients whose shares are held of record in this manner.

Additional Purchase Information

Retirement Plans/Education Savings Plans. The Fund makes available IRAs and Coverdell Education Savings Plans for investment in Fund shares. Applications may be obtained from the Distributor by calling 800-GABELLI (800-422-3554). Self-employed investors may purchase shares of the Fund through tax-deductible contributions to existing retirement plans for self-employed persons, known as “Keogh” or “H.R.-10” plans. The Fund does not currently act as a sponsor to such plans. Fund shares may also be a suitable investment for other types of qualified pension or profit sharing plans which are employer sponsored, including deferred compensation or salary reduction plans known as “401(k) Plans.” For Class AAA, A, and C shares, the minimum initial investment in all such retirement and education savings plans is $250. There is no minimum subsequent investment for retirement or education savings plans.

Automatic Investment Plan. The Fund offers an automatic monthly investment plan. For Class AAA, A, and C shares, there is no minimum initial investment for accounts establishing an automatic investment plan. Call your financial intermediary or the Distributor at 800-GABELLI (800-422-3554) for more details about the plan.

Telephone or Internet Investment Plan. You may purchase additional shares of the Fund by telephone and/or over the Internet if your bank is a member of the ACH system. You must have a completed and approved Account Options Form on file with the Transfer Agent. There is a minimum of $100 for each telephone or Internet investment. However, you may split the $100 minimum between two funds. To initiate an ACH purchase, please call your financial intermediary or 800-GABELLI (800-422-3554) or 800-872-5365 or visit our website at www.gabelli.com.

Voluntary Conversion. Shareholders may be able to convert shares to Class I shares of the Fund, which have a lower expense ratio, provided certain conditions are met. For Class A and Class C shares, this conversion feature is intended for shares held through a financial intermediary offering a fee-based or wrap fee program that has an agreement with the Adviser or the Distributor specific for this purpose. Shareholders who currently hold Class AAA shares and are eligible to purchase Class I shares may convert existing Class AAA shares of the same Fund through their financial intermediary if their financial intermediary has a specific agreement with the Distributor. In such instances, Class AAA, Class A and Class C shares may be converted under certain circumstances. Generally, Class C shares are not eligible for conversion until the applicable CDSC period has expired. Under current interpretation of applicable federal income tax law by the Internal Revenue Service, voluntary conversions to a different class of shares generally should not be treated as a taxable event. Please contact your financial intermediary for additional information. Not all share classes are available through all financial intermediaries.

If shares of the Fund are converted to a different share class of the Fund, the transaction will be based on the respective NAV of each class as of the trade date of the conversion. Consequently, a shareholder may receive fewer shares or more shares than originally owned, depending on that day’s NAVs. Please contact your tax adviser regarding the tax consequences of any conversion.

Conversion of Class C shares to Class A shares. Investors whose accounts are held at the Fund’s transfer agent are eligible to hold Class C shares of the Fund only until the month of the 8-year anniversary of the purchase date. In the month of the 8-year anniversary of the purchase date, the Fund will convert such an investor’s Class C shares into Class A shares. This conversion will not be subject to any sales charge, fee, or other charge, and will be based on the relative NAVs of the two classes in question. The Internal Revenue Service currently takes the position that such conversions are not taxable. Should its position change, the conversion feature may be suspended. If this were to happen, you would have the option of instructing the Fund to continue to convert your Class C shares of the Fund to Class A shares of the Fund at the anniversary date described above. This conversion would also be based on the relative NAVs of the two classes in question, without the imposition of a sales charge or fee, but you might face certain tax consequences as a result. Shareholders should consult with their tax advisor regarding the state and local tax consequences of such conversions.

Investors holding Class C shares of the Fund through a financial intermediary in “street name” may be subject to different eligibility requirements regarding the holding of Class C shares of the Fund. In this regard, a financial intermediary may sponsor and/or control accounts, programs or platforms that impose a different conversion schedule or different eligibility requirements for the conversion of Class C shares into Class A shares. In these cases, Class C shares of the Fund may be converted to Class A shares under the policies of the financial intermediary and the conversion may be structured as an exchange of Class C shares for Class A shares of the Fund. Financial intermediaries will be responsible for making such exchanges in those circumstances.

Please consult with your financial intermediary if you have any questions regarding your shares’ conversion from Class C shares to Class A shares. To the extent a financial intermediary’s policies provide for no such conversion, or for a conversion schedule that extends beyond the month of the 8-year anniversary of the purchase date, investors holding Class C shares through such financial intermediary may be disadvantaged relative to investors holding Class C shares either at the Fund’s transfer agent or through another financial intermediary. Because Class C shares pay higher ongoing asset-based distribution and shareholder servicing fees than Class A shares, financial intermediaries may have a conflict of interest in establishing their relevant conversion schedules and eligibility requirements. Additional information can be found in Appendix A, “Sales Charge Reductions and Waivers Available Through Certain Intermediaries,” attached to the Fund’s prospectus.

Conversion Among Classes Based on Eligibility Criteria. Shareholders who hold their shares of the Fund directly at the Fund’s transfer agent are only eligible to hold the class of Fund shares with the lowest Distribution and Service (Rule 12b-1) Fees for which such shareholders are otherwise eligible to purchase or hold based on the minimum investment requirements and other eligibility criteria for that class.

In determining whether a shareholder is eligible to continue to hold any particular class of Fund shares, the Adviser considers each class’s minimum investment requirements and other eligibility criteria. See “Classes of Shares” herein.

The Adviser will make the foregoing eligibility determinations at least once per calendar year (the “Determination Date”). Based on this determination, if a shareholder who holds its shares directly at the Fund’s transfer agent is eligible to hold a class of Fund shares with lower Distribution and Service (Rule 12b-1) Fees, any of such shareholder’s shares not already held as that class will be converted to that class within approximately 30 calendar days following the Determination Date. In no event will a shareholder’s shares be converted to a class of shares bearing higher Distribution and Service (Rule 12b-1) Fees, irrespective of the foregoing eligibility determinations.

For U.S. federal income tax purposes, the conversion of a shareholder’s investment from one class of shares of the Fund to another class of shares of the Fund generally should not result in the recognition of gain or loss. Thus, in general, the shareholder’s tax basis in the new class of shares immediately after the conversion should equal the shareholder’s tax basis in the converted shares immediately before the conversion, and the holding period of the new class of shares should include the holding period of the converted shares.

REDEMPTION OF SHARES

You can redeem shares of the Fund on any Business Day. The Fund may temporarily stop redeeming its shares beyond seven (7) days when the NYSE is closed, when trading on the NYSE is restricted (as determined by the Securities and Exchange Commission (“SEC”)), or when an emergency exists (as determined by the SEC), and the Fund cannot sell its portfolio securities or accurately determine the value of its assets, or if the SEC orders the Fund to suspend redemptions.

The Fund redeems its shares based on the NAV per share next determined after the time as of which the Fund or, if applicable, its authorized designee, receives your redemption request in proper form, subject in some cases to a redemption fee or a CDSC, as described under “Classes of Shares — Contingent Deferred Sales Charges” or a redemption fee as described below in this section. See “Pricing of Fund Shares”

herein for a description of the calculation of NAV. A redemption is a taxable event to you on which you would realize gain or loss (subject to certain limitations on the deductibility of losses). In instances where a redemption fee is triggered, a CDSC may also apply, as described in greater detail in other parts of this prospectus. The purchase and redemption of shares under the ReFlow Liquidity Program are exempt from the 2.00% short term trading fee policy that is described below, as these transactions do not raise market timing or excessive trading concerns.

You may redeem shares through a broker-dealer or other financial intermediary that has entered into a selling agreement with the Distributor. The broker-dealer or other financial intermediary will transmit a redemption order to SS&C GIDS on your behalf. The redemption request will be effected at the NAV next determined (less any applicable CDSC) after the Fund or, if applicable, its authorized designee, receives the request in proper form. If you hold share certificates, you must present the certificates endorsed for transfer.

The Fund is intended for long term investors and not for those who wish to trade frequently in Fund shares. The Fund believes that excessive short term trading of Fund shares creates risks for the Fund and its long term shareholders, including interference with efficient portfolio management, increased administrative and brokerage costs, and potential dilution in the value of Fund shares.

In addition, because the Fund may invest in foreign securities traded primarily on markets that close prior to the time the Fund determines its NAV, frequent trading by some shareholders may, in certain circumstances, dilute the value of Fund shares held by other shareholders. This may occur when an event that affects the value of the foreign securities takes place after the close of the primary foreign market, but before the time that the Fund determines its NAV. Certain investors may seek to take advantage of the fact that there will be a delay in the adjustment of the market price for a security caused by this event until the foreign market reopens (referred to as price arbitrage). If this occurs, frequent traders who attempt this type of price arbitrage may dilute the value of the Fund’s shares to the extent they receive shares or proceeds based upon NAVs that have been calculated using the closing market prices for foreign securities, if those prices have not been adjusted to reflect a change in the fair value of the foreign securities. In an effort to prevent price arbitrage, the Fund has procedures designed to adjust closing market prices of foreign securities before it calculates its NAV when it believes such an event has occurred that will have more than a minimal effect on the NAV. Prices are adjusted to reflect what the Fund believes are the fair values of these foreign securities at the time the Fund determines its NAV (called fair value pricing). Fair value pricing, however, involves judgments that are inherently subjective and inexact since it is not always possible to be sure when an event will affect a market price and to what extent. As a result, there can be no assurance that fair value pricing will always eliminate the risk of price arbitrage.

In order to discourage frequent short term trading in Fund shares, the Fund has adopted policies and procedures that impose a 2.00% redemption fee (short term trading fee) on shares that are redeemed or exchanged within seven days of a purchase. This fee is calculated based on the shares’ aggregate NAV on the date of redemption and deducted from the redemption proceeds. The redemption fee is not a sales charge; it is retained by the Fund and does not benefit the Fund’s Adviser, the Distributor, or any third party. For purposes of computing the redemption fee, shares will be redeemed in reverse order of purchase (the latest shares acquired will be treated as being redeemed first). Redemptions to which the fee applies include redemption of shares resulting from an exchange made pursuant to the Fund’s exchange privilege. The redemption fee will not apply to redemptions of shares where (i) the shares were purchased through

automatic reinvestment of dividends or other distributions, (ii) the redemption is initiated by the Fund, (iii) the shares were purchased through programs that collect the redemption fees at the program level and remit them to the Fund, or (iv) the shares were purchased through programs that the Adviser determines to have appropriate anti-short term trading policies in place or as to which the Adviser has received assurances that look through redemption fee procedures or effective anti-short term trading policies and procedures are in place.

While the Fund has entered into information sharing agreements with financial intermediaries which contractually require such financial intermediaries to provide the Fund with information relating to their customers investing in the Fund through non-disclosed or omnibus accounts, the Fund cannot guarantee the accuracy of the information provided to it from financial intermediaries and may not always be able to track short term trading effected through these financial intermediaries. In addition, because the Fund is required to rely on information provided by the financial intermediary as to the applicable redemption fee, the Fund cannot guarantee that the financial intermediary is always imposing such fee on the underlying shareholder in accordance with the Fund’s policies. Subject to the exclusions discussed above, the Fund seeks to apply these policies uniformly.

Certain financial intermediaries may have procedures which differ from those of the Fund to collect the redemption fees or that prevent or restrict frequent trading. Investors should refer to their intermediary’s policies on frequent trading restrictions.

The Fund continues to reserve all rights, including the right to refuse any purchase request (including requests to purchase by exchange) from any person or group who, in the Fund’s view, is likely to engage in excessive trading or if such purchase is not in the best interest of the Fund and to limit, delay, or impose other conditions on exchanges or purchases. The Fund has adopted a policy of seeking to minimize short term trading in its shares and monitors purchase and redemption activities to assist in minimizing short term trading.

If you hold shares directly through the Distributor, you may redeem shares:

If you redeem shares through your broker or other financial intermediary, the broker or financial intermediary will transmit a redemption order to SS&C GIDS on your behalf. The redemption request will be effected at the NAV per share next determined (less any applicable CDSC and redemption fee, if applicable) after the Fund receives the request in proper form. If you hold share certificates, you must present the certificates endorsed for transfer.

Automatic Cash Withdrawal Plan. You may automatically redeem shares on a monthly, quarterly, or annual basis if you have at least $10,000 in your account and if your account is directly registered with SS&C GIDS. Please call 800-GABELLI (800-422-3554) for more information about this plan.

Involuntary Redemption. The Fund may redeem all shares in your account (other than an IRA or Coverdell education savings account) if the value falls below $1,000 as a result of redemptions (but not as a result of a decline in NAV). You will be notified in writing before the Fund initiates such action and you will be allowed thirty days to increase the value of your account to at least $1,000.

Reinstatement Privilege. A shareholder in the Fund who has redeemed Class A shares may reinvest, without a sales charge, up to the full amount of such redemption at the NAV determined at the time of the reinvestment within ninety days of the original redemption. A redemption is a taxable transaction and a gain or loss may be recognized for federal income tax purposes even if the reinstatement privilege is exercised. However, any loss realized upon the redemption will not be recognized as to the number of shares acquired by reinstatement within thirty days of the redemption, in which case an adjustment will be made to the tax basis of the shares so acquired.

Redemption Proceeds. The Fund expects to meet redemption requests typically by selling portfolio assets, with holdings of cash and cash equivalents, or by drawing on its line of credit. In certain circumstances, the Fund may meet a redemption request in-kind, as described under “Redemption In Kind.” These methods of meeting redemption requests are expected to be used in both normal and stressed market conditions. A redemption request received by the Fund will be effected based on the NAV per share next determined after the time as of which the Fund or, if applicable, its authorized designee, receives the request. If you request redemption proceeds by wire, the Fund will normally wire the funds according to the wire instructions you

provide, within three business days after receipt of your redemption request. If you request redemption proceeds by check, the Fund will normally mail the check to you within seven days after receipt of your redemption request. If you purchased your Fund shares by check or through the Automatic Investment Plan you may not receive proceeds from your redemption until the check clears or ten days following the purchase, whichever is earlier. While the Fund will delay the processing of the redemption payment until the check clears, your shares will be valued at the next determined NAV after receipt of your redemption request. Typically, the Fund receives redemption requests through the National Securities Clearing Corporation (“NSCC”) system, which is utilized by financial intermediaries to submit requests on behalf of their clients or customers who hold shares of the Fund in “street name.” In such circumstances, the Fund expects redemption proceeds to be delivered via the NSCC system within three business days after receipt of a redemption request. The NSCC system is not used for shareholders whose accounts are held at the Fund’s transfer agent (as opposed to shareholders whose accounts are held in “street name” at a broker or other financial intermediary).

Redemption In Kind. The Fund may pay your redemption proceeds wholly or partially in portfolio securities. Specifically, the Fund may pay your redemption proceeds in portfolio securities if (a) you redeem more than $250,000 over the preceding three months, and (b) either the Adviser believes that economic conditions exist which would make payments in cash detrimental to the best interests of the Fund or you have indicated a preference to the Fund for redemptions in kind. In either such an instance, the Fund would communicate to you its intention to meet your redemption request in portfolio securities. The Fund intends to honor requests from shareholders for in kind redemptions where it is practicable to do so and otherwise in the best interest of the Fund.

Securities received in kind will remain subject to the risk of market fluctuations until sold; however, the Fund’s policy is only to distribute securities to you from its portfolio of investments that meet the following criteria: (i) traded on a major stock exchange and have a free float of at least $500 million, or (ii) the subject of a publicly announced takeout transaction pursuant to which each party thereto has executed a binding transaction agreement and in which there is no pending litigation challenging the completion of the transaction. In either case, the Fund will not distribute an amount of securities of a particular issuer that exceeds 25% of the average daily trading volume of such security over the preceding 20 trading days.

The specific security or securities to be distributed will be selected by an ad hoc committee of independent Board members pursuant to a written policy adopted by the Board, including the independent Board members. Subject to the Fund’s redemption in kind policy, and any applicable laws or regulations, the securities to be distributed could be individual securities, a representative basket of securities or a pro-rata slice of the Fund’s portfolio securities that are traded on a major stock exchange and have a free float of at least $500 million. In identifying potential individual securities to be distributed, the Fund’s redemption in kind policy favors securities with significant levels of unrealized capital appreciation and, within that category, further favors securities that are the subject of a publicly announced takeout transaction pursuant to which each party thereto has executed a binding transaction agreement and in which there is no pending litigation challenging the completion of the transaction. Any additional remainder in value owed to you between such securities and Fund shares that you submitted for redemption would be paid to you in cash. The ad hoc committee of independent Board members also has the authority to reject a redemption in kind, and require a cash redemption.

Shareholders would be paid in portfolio securities without their prior consent or request only in instances where the ad hoc committee of independent Board members believes that it would be in the Fund’s best interest not to pay the redemption proceeds in cash. A redemption in kind would be a taxable event to you on which you would realize a capital gain or capital loss on your shares redeemed. Additionally, you may incur brokerage costs in converting any of the securities received to cash. The foregoing considerations apply in both normal and stressed market considerations. Redemptions in kind by ReFlow are subject to the procedures described in the section titled “Investment Objectives, Investment Strategies, and Related Risks — ReFlow Liquidity Program.” Please see “Redemption of Shares” in the SAI for additional information.

EXCHANGE OF SHARES

You can exchange shares of the Fund for shares of the same or similar class of certain other funds managed by the Adviser or its affiliates based on their relative NAVs at the time of exchange. To obtain a list of the funds whose shares you may acquire through an exchange, call 800-GABELLI (800-422-3554) or contact your broker. Class C shares will continue to age from the date of the original purchase of such shares and will assume the CDSC rate such shares had at the time of exchange. You may also exchange your shares for shares of the same class of a money market fund managed by the Adviser or its affiliates, without imposition of any CDSC at the time of exchange. Upon subsequent redemption from such money market fund or the Fund (after re-exchange into the Fund), such shares will be subject to the CDSC calculated by excluding the time such shares were held in a Gabelli money market fund. The Fund may impose limitations on, or terminate, the exchange privilege with respect to any investor at any time. You will be given notice at least sixty days prior to any material change in the exchange privilege. An exchange of shares is a taxable event to you on which you would realize a capital gain or capital loss (subject to possible limitations of deductibility).

In effecting an exchange:

You may exchange shares through the Distributor, directly through the Transfer Agent, or through a financial intermediary that has entered into the appropriate selling agreement with the Distributor.

Your financial intermediary may charge you a processing fee for assisting you in purchasing or redeeming shares of the Fund. This charge is set by your financial intermediary and does not benefit the Fund, the Distributor, or the Adviser in any way. It would be in addition to the sales charges and other costs, if any, described in this prospectus and must be disclosed to you by your broker-dealer or other financial intermediary.

PRICING OF FUND SHARES

The Fund’s NAV is calculated separately for each class of shares on each Business Day. The NYSE is open Monday through Friday, but currently is scheduled to be closed on New Year’s Day, Martin Luther King, Jr. Day, Presidents’ Day, Good Friday, Memorial Day, Juneteenth National Independence Day, Independence Day, Labor Day, Thanksgiving Day, and Christmas Day and on the preceding Friday or subsequent Monday when a holiday falls on a Saturday or Sunday, respectively.

The Fund’s NAV is determined as of the close of regular trading on the NYSE, normally 4:00 p.m. Eastern Time. The NAV of each class is computed by dividing the value of the Fund’s net assets, i.e., the value of its securities and other assets less its liabilities, including expenses payable or accrued but excluding capital stock and surplus attributable to the applicable class of shares by the total number of shares of such class outstanding at the time the determination is made. The price of Fund shares for the purpose of purchase and redemption orders will be based upon the calculation of the NAV of each class next made after the time as of which the purchase or redemption order is received in proper form. Because the Fund may invest in foreign securities that are primarily listed on foreign exchanges that trade on weekends or other days when the Fund does not price its shares, the NAV of the Fund’s shares may change on days when shareholders will not be able to purchase or redeem the Fund’s shares.

Equity securities listed or traded on a nationally recognized securities exchange or traded in the U.S. over-the-counter market where trades are reported contemporaneously and for which market quotations are readily available are valued at the last quoted sale or a market’s official closing price at the close of the exchange’s or other market’s regular trading hours, as of or prior to the time and day as of which such value is being determined. Portfolio securities traded on more than one national securities exchange or market are valued according to the broadest and most representative market as determined by the Adviser. If there has been no sale on the day the valuation is made, the securities are valued at the mean of the closing bid

and ask prices on the principal market for such security on such day. If no ask prices are quoted on such day, then the security is valued at the closing bid price on the principal market for such security on such day. If no bid or ask prices are quoted on such day, the Fund’s accounting agent will notify the Adviser and the security will be valued based on written or standing instructions from the Adviser.

Equity securities that are primarily traded on foreign markets, except for those that trade primarily in Latin America or South America, are generally valued at the preceding closing values of such securities on their respective exchanges. Equity securities which are primarily traded in Latin American or South American markets are valued each day approximately at the time of the close of regular trading on the NYSE as though such time were the close of trading on such Latin American or South American market and such Latin American or South American market were a U.S. market. When the NYSE is open, but the foreign market on which an equity security primarily trades is closed, such as for a foreign national holiday, the security will generally be valued at the last available closing value (subject to the Fair Value Procedures adopted pursuant to Rule 2a-5 under the 1940 Act) using the prevailing exchange rate as described below. If some event occurs affecting or likely to affect the price of an equity security or group of equity securities to a significant extent including but not limited to material market movement, changes in market conditions after a foreign market closes, but prior to 4:00 p.m. Eastern Time, or a company development, such as a material business development, dividend declaration, stock split or rights offering, and if adequate and timely information relating to the event is not available or is not taken into account by the pricing service, the Adviser should review the pricing furnished by the pricing service to determine whether it is appropriate in the circumstances. In such case, the Adviser will obtain market quotations from another source or will make a fair value determination of such securities using other appropriate value measurements. If the primary market for such an equity security suspends or limits trading or price movements, whether for the market as a whole or the particular security, and trading also occurs on a secondary market which has not suspended or limited trading or price movement, valuation will be based on information from the secondary market provided by the Adviser. If all markets on which such an equity security have suspended trading, the Adviser will fair value such security as provided above. Information that becomes known after the close of the NYSE, normally 4:00 p.m. Eastern time, on any business day may be assessed in determining NAV per share after the time of receipt of the information, but will not be used to retroactively adjust the price of the security determined earlier or on a prior day.

Initial public offering securities are initially valued at cost. Upon commencement of trading, these securities are valued like any other equity security.

Debt obligations (including convertible debt) for which market quotations are readily available are valued at the average of the latest bid and ask prices. If there were no ask prices quoted on such day, the security is valued using the closing bid price. Such debt obligations are valued through prices provided by a pricing service overseen by the Adviser.

Assets and liabilities denominated in foreign currencies will be translated into U.S. dollars at the prevailing exchange rates as provided by an appropriate pricing service. Forward currency exchange contracts will be valued using interpolated forward exchange rates. Prevailing foreign exchange rates and forward currency foreign exchange rates may generally be obtained on a consistent basis at approximately 11:00 a.m. Eastern time, which approximates the close of the London Exchange. As available and as provided by an appropriate pricing service, translation of foreign security and currency market values will also occur with the use of foreign exchange rates obtained at the close of the NYSE, normally 4:00 p.m. Eastern time.

Certain securities are valued principally using dealer quotations. Futures contracts are valued at the closing settlement price of the exchange or board of trade on which the applicable contract is traded.

Over-the-counter futures and options on futures for which market quotations are readily available will be valued by quotations received from a pricing service or, if no quotations are available from a pricing service, by quotations obtained from one or more dealers in the instrument in question by the Adviser.

Securities and other assets for which market quotations are not readily available are fair valued as determined by the Adviser, as Valuation Designee, pursuant to Fair Value Procedures adopted pursuant to Rule 2a-5 under the 1940 Act. Fair valuation methodologies and procedures may include, but are not limited to: analysis and review of available financial and non-financial information about the company; comparisons with the valuation and changes in valuation of similar securities, including a comparison of foreign securities with the equivalent U.S. dollar value American Depositary Receipt securities at the close of the U.S. exchange; and evaluation of any other information that could be indicative of the value of the security.

DIVIDENDS AND DISTRIBUTIONS

The Fund intends to pay dividends, if any, monthly, and to distribute, at least annually, substantially all net capital gain. You may have dividends and/or capital gain distributions that are declared by the Fund reinvested automatically at NAV in additional shares of the Fund. You will make an election to receive dividends and distributions in cash or Fund shares at the time you first purchase your shares. You may change this election by notifying the Fund or your financial intermediary in writing at any time prior to the record date for a particular dividend or distribution. There are no sales or other charges by the Fund in connection with the reinvestment of dividends and capital gain distributions. Shares purchased through dividend reinvestment will receive a price without sales charge based on the NAV on the reinvestment date, which is typically the date dividends are paid to shareholders. There can be no assurance that the Fund will realize any capital gains or other income with which to pay dividends and distributions. Distributions are taxable to you whether received in cash or additional shares. This policy may be changed by the Board at any time. To the extent that distributions are in excess of the Fund’s current and accumulated earnings and profits, the distributions will be treated as a non-taxable return of capital. A dividend or capital gain distribution paid on shares purchased shortly before the record date for that dividend or distribution will generally be subject to income taxes even though the dividend or capital gain distribution represents, in substance, a partial return of capital. Dividends sourced from paid-in capital should not be considered as dividend yield or the total return from an investment in the Fund. Dividends and distributions are taxable whether paid in cash or reinvested in additional shares. Dividends and distributions may be different for different classes of shares of the Fund.

Fixed Distribution Policy Risk. The Fund generally seeks to distribute a fixed amount each month to each class of shares, which amount may differ from class to class (the “Fixed Distribution Policy”). Section 19(b) of the 1940 Act and Rule 19b-1 promulgated thereunder limit the number of distributions of long-term capital gain a fund may make in any particular year. Depending on the circumstances, in order to remain in compliance with Rule 19b-1, the operation of the Fund’s monthly Fixed Distribution Policy may require shareholders to pay tax on distributions at a higher rate than they otherwise would experience or

may require them to make special tax filings to offset additional tax payments made by the Fund. In extreme circumstances, compliance with Rule 19b-1 could have a material adverse effect on the Fund’s investment program.

Rule 19b-1 contains a mechanism for a fund to request relief from the SEC to spread its long-term capital gain over up to all of its distributions in the event of unforeseen circumstances. Due to a very high level of net redemptions in 2015 compared to prior years while having very large amounts of unrealized long-term capital gain and very small amounts of unrealized long-term capital loss, in order to avert adverse consequences for the Fund and its shareholders, the Fund sought and received such SEC relief for 2015. However, the Fund believes it is unlikely to be able to obtain such relief in similar circumstances in the future. Accordingly, the Fund will monitor its distribution, estimated sources of income and tax situation carefully and may modify its Fixed Distribution Policy from time to time in an effort to reduce the likelihood of material adverse impacts in the future.

TAX INFORMATION

The Fund expects that distributions will consist primarily of investment company taxable income and net capital gain. Dividends out of investment company taxable income (including distributions of net short term capital gains, i.e., gains from securities held by the Fund for one year or less) are taxable to you as ordinary income if you are a U.S. shareholder, except that certain qualified dividends may be eligible for a reduced rate (provided certain holding period and other requirements are met). Properly reported distributions of net capital gain, i.e., net long term capital gains minus net short term capital loss (“Capital Gain Dividends”), are taxable to you at long term capital gain rates no matter how long you have owned your shares. To the extent distributions are made from current earnings and profits, they are considered ordinary income or long term capital gains. Currently, distributions are expected to include return of capital distributions, which are distributions in excess of current and accumulated earnings and profits. A return of capital distribution is tax-free to the extent of a shareholder’s basis in its Fund shares and reduces the shareholder’s basis to that extent. After that basis has been reduced to zero, any excess return of capital distributions will generally be treated as capital gain. The current policy of paying a monthly distribution in excess of net investment income, together with 1940 Act limitations on the Fund’s ability to designate Capital Gain Dividends, may restrict the Fund’s ability to pay out all of its net capital gains as a Capital Gain Dividend. The Fund’s distributions, whether you receive them in cash or reinvest them in additional shares of the Fund, generally will be subject to federal and, if applicable, state and local taxes. A redemption of Fund shares or an exchange of the Fund’s shares for shares of another fund will be treated for tax purposes as a sale of the Fund’s shares, and any gain you realize on such a transaction generally will be taxable. Foreign shareholders may be subject to a federal withholding tax.

A dividend declared by the Fund in October, November, or December and paid during January of the following year may in certain circumstances be treated as paid in December for tax purposes.

After the end of each year, the Fund will provide you with the information regarding any shares you redeemed and the federal tax status of any dividends or distributions you received during the previous year.

Certain non-corporate U.S. shareholders whose income exceeds certain thresholds will be required to pay a 3.8% Medicare tax on dividend and other investment income, including dividends received from the Fund and capital gains from the sale or other disposition of the Fund’s stock.

By law, the Fund must withhold, as backup withholding, a percentage of your taxable distributions and redemption proceeds if you do not provide your correct social security or taxpayer identification number and certify that you are not subject to backup withholding, or if the Internal Revenue Service instructs the Fund to do so.

This summary of tax consequences is intended for general information only and is subject to change by legislative, judicial, or administrative action, and any such change may be retroactive. A more complete discussion of the tax rules applicable to you and the Fund can be found in the SAI that is incorporated by reference into this prospectus. You should consult a tax adviser concerning the tax consequences of your investment in the Fund.

MAILINGS AND E-DELIVERY TO SHAREHOLDERS

In our continuing efforts to reduce duplicative mail and Fund expenses, we currently send a single copy of prospectuses and shareholder reports to your household even if more than one member in your household owns the same fund or funds described in the prospectus or report. Additional copies of our prospectuses and reports may be obtained by calling 800-GABELLI (800-422-3554). If you do not want us to continue to consolidate your fund mailings and would prefer to receive separate mailings at any time in the future, please call us at the telephone number above and we shall resume separate mailings, in accordance with your instructions within thirty days of your request. The Fund offers electronic delivery of Fund documents. Direct shareholders of the Fund can elect to receive the Fund’s annual, semiannual, and quarterly reports, as well as manager commentaries and prospectuses via e-delivery. For more information or to sign up for e-delivery, please visit the Fund’s website at www.gabelli.com. Shareholders who purchased shares of the Fund through a financial intermediary should contact their financial intermediary to sign up for e-delivery of Fund documents, if available.

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the financial performance of the Fund for the past five fiscal years of the Fund’s Class AAA, Class A, Class C, and Class I shares. The total returns in the table represent the percentage amount that an investor would have earned or lost on an investment in the designated class of shares (assuming reinvestment of all distributions). This information has been audited by Ernst & Young LLP, independent registered public accounting firm, whose report, along with the Fund’s financial statements and related notes, is included in the Fund’s Form N-CSR, which is available upon request.

The Gabelli Utilities Fund

Financial Highlights

Selected data for a share of beneficial interest outstanding throughout each year: