FTRSF Fortis Inc (PK)

Investing in the Common Shares involves certain risks that should be carefully considered. See the "Risk Factors" section of the Prospectus, as well as "Risks Related to the Common Shares" in this Prospectus Supplement.

The sale of the Offered Shares to the Subscribers will be settled under the book-based system through the facilities of The Depository Trust Company, or DTC, or by such other means as we and the Subscribers may agree. Unless otherwise determined by the Corporation and the Subscribers, the Subscribers will receive only a customer confirmation from the registered dealer that is a DTC participant through which the Offered Shares are purchased.

This Offering is being made by a Canadian issuer that is permitted, under the multi-jurisdictional disclosure system adopted by the U.S. and Canada, or MJDS, to prepare this Prospectus Supplement in accordance with Canadian disclosure requirements. You should be aware that such requirements are different from U.S. disclosure requirements. Financial statements incorporated by reference herein have been prepared in accordance with U.S. generally accepted accounting principles, or U.S. GAAP.

Table of Contents

The acquisition of the securities described herein may subject you to tax consequences in both the U.S. and Canada. This Prospectus Supplement does not describe these tax consequences. See "Certain Canadian and U.S. Federal Income Tax Considerations".

Your ability to enforce civil liabilities under U.S. federal securities laws may be affected adversely because Fortis is incorporated under the laws of the Province of Newfoundland and Labrador, Canada, some of the Corporation's officers and directors and some of the experts named in this Prospectus Supplement and the Prospectus are non-U.S. residents, and some of the Corporation's assets and some of the assets of those officers, directors and experts are located outside of the U.S. See "Enforceability of Civil Liabilities".

Six of our directors, Mr. Paul J. Bonavia, Mr. Lawrence T. Borgard, Ms. Maura J. Clark, Ms. Margarita K. Dilley, Ms. Julie A. Dobson and Mr. Joseph L. Welch, reside outside of Canada and each has appointed Fortis Inc., Suite 1100, 5 Springdale Street, P.O. Box 8837, St. John's, Newfoundland and Labrador A1B 3T2, as agent for service of process. You are advised that it may not be possible to enforce judgments obtained in Canada against any person that resides outside of Canada, even if such person has appointed an agent for service of process.

THE SECURITIES OFFERED HEREIN HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SEC, NOR HAS THE SEC OR ANY STATE OR CANADIAN SECURITIES REGULATOR PASSED UPON THE ADEQUACY OR ACCURACY OF THIS PROSPECTUS SUPPLEMENT OR THE PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

No underwriter or dealer has been involved in the preparation of, or has performed any review of, this Prospectus Supplement or the Prospectus.

The Corporation's head and registered office are located at Suite 1100, 5 Springdale Street, St. John's, Newfoundland and Labrador A1E 0E4.

Table of Contents

TABLE OF CONTENTS
Prospectus Supplement

Table of Contents

NOTICE TO READERS

        This document is in two parts. The first part is this Prospectus Supplement, which describes the specific terms of the Offering and also adds to and updates certain information contained in the Prospectus and the documents incorporated by reference herein and therein. The second part is the Prospectus, which gives more general information, some of which may not apply to the Offering. This Prospectus Supplement is deemed to be incorporated by reference in the Prospectus solely for the purpose of the Offering.

        If the description of the Common Shares varies between this Prospectus Supplement and the Prospectus, you should rely on the information in this Prospectus Supplement.

        You should rely only on the information contained in or incorporated by reference in this Prospectus Supplement and the Prospectus. We have not authorized anyone to provide you with different or additional information. We are not making an offer of Common Shares in any jurisdiction where the offer is not permitted by law. The information contained in this Prospectus Supplement, the Prospectus and the documents incorporated by reference herein and therein is accurate only as of the respective dates of those documents, and you should not assume otherwise.

        We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference into this Prospectus Supplement and the accompanying Prospectus were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties and covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

        Unless we have indicated otherwise, or the context otherwise requires, references in this Prospectus Supplement to "Fortis", the "Corporation", "we", "us" and "our" refer to Fortis Inc. and its consolidated subsidiaries.

SPECIAL NOTE REGARDING FORWARD-LOOKING INFORMATION

        This Prospectus Supplement and the Prospectus, including the documents incorporated by reference herein and therein, contain forward-looking information within the meaning of applicable Canadian securities laws and forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995 (collectively referred to herein as "forward-looking information"). The forward-looking information reflects our current expectations regarding our future growth, results of operations, performance, business prospects and opportunities. The words anticipates, assumes, believes, budgets, can, could, estimates, expects, forecasts, intends, may, might, opportunity, plans, projects, schedule, seeks, should, target, will, would and the negative of these terms and other similar expressions are often intended to identify forward-looking information.

        The forward-looking information in this Prospectus Supplement and the Prospectus, including the documents incorporated by reference herein and therein, includes, but is not limited to, statements regarding: the aggregate amount of the total proceeds that we will receive pursuant to the Offering and the expected uses of such proceeds; the expectation that the Concurrent Offering (as defined below) will be completed; the aggregate amount of the gross proceeds of the Concurrent Offering and the expected uses of such proceeds; the expectation that the Corporation's equity requirements will be satisfied through the Offering, the Concurrent Offering and the dividend reinvestment and share purchase plan, or DRIP and as a result, the ATM Distribution (as defined below) is no longer necessary; the expectation that the Corporation will eliminate the discount under its DRIP prior to payment of its March 1, 2020 dividend and that the rate of participation in the DRIP by the Corporation's shareholders may decrease as a result; targeted average annual dividend growth through 2024; forecast capital expenditures for 2019 and the period 2020 through 2024 and potential funding sources for the capital plan; expected timing of filing of regulatory applications and timing, outcome and impact of regulatory decisions; expected or potential funding sources for operating expenses, interest costs and capital expenditure plans; the expectation that maintaining the targeted capital structure of the regulated operating subsidiaries will not have an impact on its ability to pay dividends in the foreseeable future; expected consolidated fixed-term debt maturities and repayments over the next five years; the expectation that the Corporation and its

S-1

Table of Contents

subsidiaries will remain compliant with debt covenants throughout 2019; the nature, timing, benefits, funding sources and expected costs of certain capital projects including the Oso Grande Wind Project, Wataynikaneyap Transmission Power Project, Eagle Mountain Woodfibre Gas Line Project, Tilbury 1B, Multi-Value Regional Transmission Projects, 34.5 to 69 kilovolt Transmission Conversion Project, Southline Transmission Project, Lower Mainland Intermediate Pressure System Upgrade; Transmission Integrity Management Capabilities Project and additional opportunities beyond the base capital expenditure plan; the expectation that the adoption of future accounting pronouncements will not have a material impact on the Corporation's consolidated financial statements and the anticipated timing for adoption; forecast rate base for 2019 and the period 2020 through 2024; the expectation that capital investment will support growth in earnings and dividends; the expectation that the Corporation and its subsidiaries will continue to have reasonable access to long-term capital in 2019; the expectation that subsidiary operating expenses and interest costs will be paid out of subsidiary operating cash flows; the expected sources of cash required of our subsidiaries and Fortis to complete subsidiary capital expenditure programs; the intent of management to refinance certain borrowings under our and our subsidiaries' long-term committed credit facilities with long-term permanent financing; the expected timing and impact, if any, of the adoption of future accounting pronouncements; statements relating to the addition of renewable capacity at Tucson Electric Power Company, or TEP; the expectation that allocated revenues recognized by ITC Holdings Corp, or ITC, from Canadian entities reserving transmission over the Ontario or Manitoba interface are not expected to be material to ITC; the expectation that TEP has sufficient generating capacity, together with existing power purchase agreements and expected generation plant additions, to satisfy the requirements of its customer base and meet future peak demand requirements; the expectation that changes in energy supply costs may increase electricity prices in a manner that adversely affects Newfoundland Power Inc.'s, or Newfoundland Power, sales; and TEP's expected share of mine reclamation costs.

        The forecasts and projections that make up the forward-looking information included in this Prospectus Supplement and the Prospectus are based on assumptions which include, but are not limited to: the receipt of applicable regulatory approvals and requested rate orders, no material adverse regulatory decisions being received, and the expectation of regulatory stability; the implementation of the five-year capital expenditure plan; no material capital project and financing cost overrun related to any of our capital projects; the realization of additional opportunities; our board of directors, or the Board of Directors, exercising its discretion to declare dividends, taking into account our business performance and financial condition; no significant variability in interest rates; no significant operational disruptions or environmental liability due to a catastrophic event or environmental upset caused by severe weather, other acts of nature or other major events; the continued ability to maintain our electricity and gas systems to ensure their continued performance; no severe and prolonged downturn in economic conditions; no significant decline in capital spending; sufficient liquidity and capital resources; the continuation of regulator-approved mechanisms to flow through the cost of natural gas and energy supply costs in customer rates; the ability to hedge exposures to fluctuations in foreign exchange rates, natural gas prices and electricity prices; no significant changes in tax laws or proposed tax laws; no significant counterparty defaults; the continued competitiveness of natural gas pricing when compared with electricity and other alternative sources of energy; the continued availability of natural gas, fuel, coal and electricity supply; continuation and regulatory approval of power supply and capacity purchase contracts; the ability to fund defined benefit pension plans, earn the assumed long-term rates of return on the related assets and recover net pension costs in customer rates; no significant changes in government energy plans, environmental laws and regulations that may materially negatively affect us or our subsidiaries; no material change in public policies and directions by governments that could materially negatively affect us or our subsidiaries; maintenance of adequate insurance coverage; the ability to obtain and maintain licences and permits; retention of existing service areas; the continued tax deferred treatment of earnings from our foreign operations; continued maintenance of information technology infrastructure and no material breach of cybersecurity; continued favourable relations with Indigenous Peoples; favourable labour relations; that we can reasonably assess the merit of and potential liability attributable to ongoing legal proceedings; and sufficient human resources to deliver service and execute the capital expenditure program.

        The forward-looking information is subject to risks, uncertainties and other factors that could cause actual results to differ materially from historical results or results anticipated by the forward-looking information. These factors should be considered carefully and undue reliance should not be placed on the forward-looking information. Factors which could cause results or events to differ from current expectations include, but are not

S-2

Table of Contents

limited to: the price at which the Offered Shares are sold in the Offering and the aggregate net proceeds received by us as a result of the Offering and Concurrent Offering; failure to obtain TSX approval for the amendment of the DRIP to eliminate the discount thereunder; uncertainty regarding the outcome of regulatory proceedings at our utilities; the impact of fluctuations in foreign exchange rates; risks relating to pending and future changes in environmental regulations; interest rate risk; risks associated with the continuation, renewal, replacement and/or regulatory approval of power supply and capacity purchase contracts; risks relating to energy prices; provincial, state and federal regulatory legislative decisions and actions; risks relating to any potential downgrade of our credit ratings; risks relating to our ability to access capital markets on favourable terms or at all; the cost of debt and equity capital; risks associated with changes in economic conditions; changes in regional economic and market conditions which could affect customer growth and energy usage; risks relating to the impact of actual loads, forecasted loads, regional economic conditions, weather conditions, union strikes, labour shortages, material and equipment prices and availability; the performance of the stock market and changing interest rate environment; risks from regulatory approvals for reasons relating to rate construct, environmental, siting, regional planning, cost recovery or other issues or as a result of legal proceedings; risks arising from variances between estimated and actual costs of construction contracts awarded and the potential for greater competition; insurance coverage risk; risk of loss of licences and permits; risk of loss of service area; risks relating to derivatives; the continued ability to hedge foreign exchange risk; counterparty risk; environmental risks; competitiveness of natural gas; natural gas, fuel, coal and electricity supply risk; risks relating to human resources and labour relations; risk of unexpected outcomes of legal proceedings currently against us; risk of not being able to access Indigenous Peoples' lands; weather and seasonality risk; commodity price risk; capital resources and liquidity risks; changes in critical accounting estimates; risks related to changes in tax legislation; the ongoing restructuring of the electric industry; changes to long-term contracts; risk of failure of information technology infrastructure and cyber-attacks or challenges to our information security; risk associated with the impacts of less favourable economic conditions on our results of operations; risk associated with the completion of our 2019 capital expenditure plan, including completion of major capital projects on the timelines anticipated and at the expected amounts; uncertainty in the timing and access to capital markets to arrange sufficient and cost-effective financing to finance, among other things, capital expenditures and the repayment of maturing debt; and certain presently unknown or unforeseen risks, including, but not limited to, acts of terrorism. This list is not exhaustive of the factors that may affect any of our forward-looking information. For additional information with respect to our risk factors and risk factors relating to the Offered Shares, reference should be made to the section of this Prospectus Supplement entitled "Risks Related to the Common Shares", the section of the Prospectus entitled "Risk Factors", to the documents incorporated by reference herein and therein and to our continuous disclosure materials filed from time to time with Canadian securities regulatory authorities and with the SEC.

        Although the Corporation has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in the forward-looking information, there may be other factors that cause actions, events or results not to be as anticipated, estimated or intended. This forward-looking information is made as of the date of this Prospectus Supplement. There can be no assurance that the forward-looking information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such information. Accordingly, readers are cautioned not to place undue reliance on the forward-looking information. All forward-looking information in this Prospectus Supplement, the Prospectus and in the documents incorporated herein and therein by reference is qualified in its entirety by the above cautionary statements and, except as required by law, we undertake no obligation to revise or update any forward-looking information as a result of new information, future events or otherwise.

S-3

Table of Contents

DOCUMENTS INCORPORATED BY REFERENCE

        This Prospectus Supplement is deemed to be incorporated by reference in the Prospectus solely for the purpose of the Offering. The following documents filed by us with the securities commission or similar authority in each of the provinces of Canada are specifically incorporated by reference in, and form an integral part of, this Prospectus Supplement and the Prospectus:

        Any document of the type referred to above, and any material change report (other than any confidential material change report), any business acquisition report and any prospectus supplement relating to the Offering disclosing additional or updated information, subsequently filed by us with such securities commissions or regulatory authorities in Canada after the date of this Prospectus Supplement, and prior to the termination of the Offering, shall be deemed to be incorporated by reference into this Prospectus Supplement and the Prospectus.

        Documents and information in an annual report on Form 40-F filed by us with the SEC under the U.S. Securities Exchange Act of 1934, as amended, or the Exchange Act, from the date of this Prospectus Supplement and prior to the termination or completion of the Offering shall be deemed to be incorporated by reference into this Prospectus Supplement and the registration statement of which this Prospectus Supplement forms a part. In addition, any other report on Form 6-K and the exhibits thereto filed or furnished by us with the SEC under the Exchange Act from the date of this Prospectus Supplement and prior to the termination or completion of the Offering shall be deemed to be incorporated by reference into this Prospectus Supplement or as exhibits to the registration statement of which this Prospectus Supplement forms a part, as applicable, but only if and to the extent expressly so provided in such reports. Our current reports on Form 6-K and our annual reports on Form 40-F are available on the SEC's Electronic Data Gathering and Retrieval website, or EDGAR, at www.sec.gov.

        Any statement contained in this Prospectus Supplement, the Prospectus or in a document incorporated or deemed to be incorporated by reference in this Prospectus Supplement or the Prospectus shall be deemed to be modified or superseded for the purposes of this Prospectus Supplement and the Prospectus to the extent that a statement contained in this Prospectus Supplement, or in any subsequently filed document which is or is deemed to be incorporated by reference in this Prospectus Supplement or the Prospectus, modifies or supersedes that statement. The modifying or superseding statement need not state that it has modified or superseded a prior statement. The making of a modifying or superseding statement shall not be deemed an admission for any purposes that the modified or superseded statement, when made, constituted a misrepresentation, an untrue statement of a material fact or an omission to state a material fact that is required to be stated or that is necessary to make a statement not misleading in light of the circumstances in which it was made. Any statement so modified or superseded shall not constitute a part of this Prospectus Supplement or the Prospectus except as so modified or superseded.

S-4

Table of Contents

WHERE YOU CAN FIND ADDITIONAL INFORMATION

        Copies of the documents incorporated in this Prospectus Supplement and the Prospectus by reference may be obtained on request without charge from our Corporate Secretary at Suite 1100, 5 Springdale Street, P.O. Box 8837, St. John's, Newfoundland and Labrador A1B 3T2 (telephone (709) 737-2800). These documents are also available through the Internet on our website at www.fortisinc.com or on the Canadian Securities Administrators' System for Electronic Document Analysis and Retrieval, or SEDAR, which can be accessed at www.sedar.com. The information contained on, or accessible through, any of these websites is not incorporated by reference into this Prospectus Supplement or the Prospectus and is not, and should not be considered to be, a part of this Prospectus Supplement or the Prospectus unless it is explicitly so incorporated.

        In addition to our continuous disclosure obligations under the securities laws of the provinces of Canada, we are subject to the informational requirements of the Exchange Act and in accordance therewith file reports and other information with the SEC. Under the MJDS, such reports and other information may be prepared in accordance with the disclosure requirements of Canada, which requirements are different from those of the U.S. Any information filed with the SEC can be read and copied at prescribed rates at the SEC's Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549. Information on the operation of the Public Reference Room may be obtained by calling the SEC at 1-800-SEC-0330 or by accessing its website at www.sec.gov. Some of the documents that we file with or furnish to the SEC are electronically available from EDGAR, and may be accessed at www.sec.gov.

        We have filed with the SEC a registration statement on Form F-10 (File No. 333-228593) under the U.S. Securities Act of 1933, as amended, or the Securities Act, with respect to the Offered Shares. This Prospectus Supplement, which forms a part of the registration statement, does not contain all of the information set forth in the registration statement, certain parts of which have been omitted in accordance with the rules and regulations of the SEC. For further information with respect to us and the Offering, reference is made to the registration statement and to the schedules and exhibits filed therewith. Statements contained in this Prospectus Supplement as to the contents of certain documents are not necessarily complete and, in each instance, reference is made to the copy of the document filed as an exhibit to the registration statement. Each such statement is qualified in its entirety by such reference.

PRESENTATION OF FINANCIAL INFORMATION

        Financial statements incorporated by reference in this Prospectus Supplement and the Prospectus have been prepared in accordance with U.S. GAAP. Certain calculations included in tables and other figures in this Prospectus Supplement and the Prospectus have been rounded for clarity of presentation.

S-5

Table of Contents

CURRENCY AND EXCHANGE RATE INFORMATION

        This Prospectus Supplement contains references to U.S. dollars and Canadian dollars. All dollar amounts referenced, unless otherwise indicated, are expressed in Canadian dollars. References to "$" or "C$" are to Canadian dollars and references to "US$" are to U.S. dollars. The following table shows, for the periods indicated, certain information regarding the Canadian dollar/U.S. dollar exchange rate. Except as indicated below, the information is based on the average daily exchange rate as reported by the Bank of Canada. Such exchange rate on November 25, 2019 was C$1.3307 = US$1.00.

THE CORPORATION

        The following description of Fortis is derived from selected information about the Corporation contained in the documents incorporated by reference and does not contain all of the information about the Corporation and its business that should be considered before investing in the Offered Shares. This Prospectus Supplement, the accompanying Prospectus and the documents incorporated by reference herein and therein should be reviewed and considered by you in connection with your investment in the Offered Shares. This Prospectus Supplement may add to, update or change information in the accompanying Prospectus. You should carefully read this entire Prospectus Supplement and the accompanying Prospectus, including the risks and uncertainties discussed in the section titled "Risks Related to the Common Shares" in this Prospectus Supplement, the section titled "Risk Factors" in the Prospectus, and the information incorporated by reference in this Prospectus Supplement, including the consolidated financial statements of the Corporation before making an investment decision.

        We are a North American electric and gas utility holding company, with total assets of approximately $53 billion as at September 30, 2019, and revenue totaling approximately $8.4 billion and $6.5 billion for the year ended December 31, 2018 and the nine months ended September 30, 2019, respectively. In 2018, our electricity distribution systems met a combined peak demand of 33,295 megawatts, or MW, and our gas distribution systems met a peak day demand of 1,599 terajoules, or TJ. For the nine months ended September 30, 2019, our electricity distribution systems met a combined peak demand of 32,441 MW and our gas distribution system met a peak day demand of 1,618 TJ. Our 8,800 employees serve customers at utility operations in five Canadian provinces, nine U.S. states and three Caribbean countries.

        Our business segments are:

(a)

Regulated Independent Transmission — United States: consisting of the electric transmission operations of ITC, which is our indirect subsidiary, with Eiffel Investment Pte Ltd (an affiliate of GIC Pte Ltd.) owning a 19.9% interest in ITC. ITC's business consists primarily of the electric transmission operations of ITC's regulated operating subsidiaries, which include International Transmission Company, Michigan Electric Transmission Company, LLC, ITC Midwest LLC, ITC Great Plains, LLC and ITC Interconnection LLC. ITC owns and operates high-voltage transmission systems in Michigan's Lower Peninsula and portions of Iowa, Minnesota, Illinois, Missouri, Kansas and Oklahoma that transmit electricity from generating stations to local distribution facilities connected to ITC's systems;

S-6

Table of Contents

(b)

Regulated Electric & Gas Utilities — United States: consisting of vertically integrated electrical and gas utilities in the state of Arizona: TEP, UNS Electric, Inc. and UNS Gas, Inc., each a subsidiary of UNS Energy Corporation, or UNS Energy; together with Central Hudson Gas & Electric Corporation, a regulated transmission and distribution utility located in New York State's Mid-Hudson River Valley;



(c)

Regulated Electric & Gas Utilities — Canadian and Caribbean: consisting of: (i) FortisBC Energy, the largest distributor of natural gas in British Columbia, serving residential, commercial and industrial and transportation customers in more than 135 communities; (ii) FortisAlberta Inc., a regulated electric distribution utility serving a substantial portion of southern and central Alberta; (iii) FortisBC Inc., an integrated, regulated electric utility serving the southern interior of British Columbia; (iv) Newfoundland Power, a regulated electric utility that operates throughout the island portion of the Province of Newfoundland and Labrador; (v) Maritime Electric Company, Limited, a regulated electric utility on Prince Edward Island; (vi) FortisOntario Inc., which provides regulated, integrated electric utility service in Fort Erie, Cornwall, Gananoque, Port Colborne and the District of Algoma in Ontario; (vii) a 39% equity investment in the Wataynikaneyap Power Limited Partnership, a power project in Ontario in the development stage; (viii) an indirect approximate 60% controlling ownership interest in Caribbean Utilities Company, Ltd., an integrated electric utility in Grand Cayman, Cayman Islands, the Class A Ordinary Shares of which are listed on the TSX under the symbol CUP.U; (ix) Fortis Turks and Caicos, integrated electric utilities on the Turks and Caicos Islands; and (x) an approximate 33% equity investment in Belize Electricity Limited, an integrated electric utility in Belize;



(d)

Non-Regulated — Energy Infrastructure: consisting of: (i) the Aitken Creek natural gas storage facility in British Columbia; and (ii) the 25-MW Mollejon, 7-MW Chalillo and 19-MW Vaca hydroelectric generating facilities in Belize; and



(e)

Non-Regulated — Corporate and Other: captures expense and revenue items not specifically related to any reportable segment and those business operations that are below the required threshold for reporting as separate segments.

S-7

Table of Contents

RECENT DEVELOPMENTS

Concurrent Offering

        Concurrently with the execution of the Subscription Agreement relating to the Offering, the Corporation entered into an agreement on November 25, 2019 with Scotia Capital Inc., on behalf of a syndicate of underwriters, or the Underwriters, pursuant to which the Corporation has agreed to sell and the Underwriters have agreed to purchase, as principals, 11,510,000 Common Shares, or the Concurrent Offering Shares, at a price of $52.15 per Concurrent Offering Share, or the Concurrent Offering Price, for total gross proceeds of approximately $600 million, or the Concurrent Offering. Fortis has agreed to pay the Underwriters a commission, or the Underwriting Commission, in connection with the Concurrent Offering.

        In connection with the Concurrent Offering, Fortis has granted the Underwriters an over-allotment option, or the Over-Allotment Option, exercisable in whole or in part within 30 days from the closing of the Concurrent Offering, to purchase up to an additional 1,726,500 Common Shares, or the Additional Shares, on the same terms as in the Concurrent Offering, solely to cover over-allotments, if any, and for market stabilization purposes. If the Over-Allotment Option is exercised in full, the total price to the public, the aggregate Underwriting Commission and the net proceeds of the Concurrent Offering will be approximately $690 million, $28 million and $663 million (before deducting other expenses of the Concurrent Offering), respectively.

        Subject to the terms and conditions set forth in the Underwriting Agreement, the Underwriters have agreed to purchase all of the Concurrent Offering Shares sold under the Underwriting Agreement if any of the Concurrent Offering Shares are purchased under the Underwriting Agreement. The Underwriters propose to offer the Concurrent Offering Shares initially at the Concurrent Offering Price. After a reasonable effort has been made by the Underwriters to sell all of the Concurrent Offering Shares at the Concurrent Offering Price, the Underwriters may subsequently reduce the selling price to investors from time to time in order to sell any of the Concurrent Offering Shares remaining unsold. Any such reduction will not affect the proceeds of the Concurrent Offering received by Fortis. The Corporation entered into an underwriting agreement, or the Underwriting Agreement, with the Underwriters relating to the Concurrent Offering on November 26, 2019.

        The Concurrent Offering will be completed pursuant to a prospectus supplement filed under the Prospectus and, while subject to certain terms and conditions contained in the Underwriting Agreement, is not conditional upon the completion of the Offering. The Concurrent Offering is expected to close on or about December 3, 2019.

Appointment of Chief Operating Officer

        On November 25, 2019, Fortis announced the appointment of David Hutchens as Chief Operating Officer of Fortis effective January 1, 2020.

        In this newly created role, Mr. Hutchens' responsibilities will broaden to include operational oversight of the Corporation's ten utilities across Canada, the United States and the Caribbean. Mr. Hutchens will also continue as Chief Executive Officer of UNS Energy in Arizona. Formerly, Mr. Hutchens held the position of Executive Vice President, Western Utility Operations with Fortis.

Termination of ATM Distribution

        In connection with the announcement of the Offering and the Concurrent Offering, Fortis has provided notice to the agents under the equity distribution agreement dated December 10, 2018 relating to its at-the-market distribution, or ATM Distribution, that it is terminating the ATM Distribution as of the date of this Prospectus Supplement. The equity required by the Corporation to fund its ongoing capital plan is expected to be obtained through the Offering, the Concurrent Offering and the Corporation's DRIP and as a result, the ATM Distribution is no longer necessary.

S-8

Table of Contents

FERC Order

        On November 21, 2019, ITC received an order from the Federal Energy Regulatory Commission, or FERC, adopting a new base return on common equity, or ROE, methodology for transmission owners in the Midcontinent Independent System Operator Inc., or MISO, region.

        FERC adjusted the base ROE to 9.88% with an upper end of the zone of reasonableness at 12.24%. Including ROE incentive adders for Regional Transmission Organization participation and independence at ITC, this implies an all-in prospective ROE of 10.63% for ITC's subsidiaries operating in the MISO footprint. This compares to an all-in ROE of 11.07% that ITC was previously accruing. Every 10-basis point change in ROE at ITC impacts earning per share at Fortis by approximately one cent per Common Share. ITC has previously recorded sufficient amounts related to the required refunds generated from the order.

Elimination of DRIP Discount

        Fortis has announced that, subject to the approval of the TSX, it will be terminating the 2% discount currently offered on the purchase of Common Shares under its DRIP with effect for the March 1, 2020 dividend. As a result of the termination by Fortis of the discount under its DRIP, Fortis expects the rate of DRIP participation by the Corporation's shareholders to decrease.

RISKS RELATED TO THE COMMON SHARES

        An investment in the Offered Shares involves certain risks. You should carefully consider the risk factors described under the heading "Business Risk Management" found on pages 30 to 40 of the Annual MD&A which is incorporated by reference herein. In addition, before making an investment decision, you should carefully consider, in light of your own financial circumstances, the risk factors set out below which relate to the Offered Shares, as well as the other information contained in this Prospectus Supplement, the Prospectus, including under the heading "Risk Factors" found on pages 20 to 21, the documents incorporated by reference herein and therein and in all subsequently filed documents incorporated by reference.

Price Volatility of Common Shares

        The market price of our Common Shares has in the past been, and may in the future be, subject to large fluctuations which may result in losses for investors. The market price of our Common Shares may increase or decrease in response to a number of events and factors, including:

•

our operating performance and the performance of competitors and other similar entities;



•

the public's reaction to our press releases, other public announcements and our filings with the various securities regulatory authorities;



•

changes in earnings estimates or recommendations by research analysts who track our securities;



•

the operating and share price performance of other entities that investors may deem comparable;



•

changes in general economic and/or political conditions;



•

changes in the regulatory regimes to which our operating subsidiaries are subject and regulatory decisions affecting our operating subsidiaries;



•

the arrival or departure of key personnel;



•

acquisitions, strategic alliances or joint ventures involving us or our competitors; and



•

the number of Offered Shares in the Offering and the number of Common Shares issued by the Corporation in any other offering, including the Concurrent Offering.

        In addition, the market price of our Common Shares is affected by many variables not directly related to our success and not within our control, including other developments that affect the market for all utilities sector securities or the equity markets generally, the breadth of the public market for our Common Shares, and the

S-9

Table of Contents

attractiveness of alternative investments. These variables may adversely affect the prices of our Common Shares regardless of our operating performance.

Uses of the Net Proceeds from the Offering and the Concurrent Offering

        We currently expect to apply the net proceeds we receive from the Offering and the Concurrent Offering as described under "Use of Proceeds" of this Prospectus Supplement. As described thereunder, management has broad discretion with respect to the actual application of those net proceeds, and may elect to apply such proceeds differently than is described thereunder if management believes that it would be in the Corporation's best interest to do so. The failure by management to apply the net proceeds effectively could have a material adverse effect on our business.

The Concurrent Offering May Not be Completed

        Completion of the Offering is not conditional on the completion of the Concurrent Offering, and closing of the Offering may occur in circumstances where the Concurrent Offering is not completed. The completion of the Concurrent Offering is subject to certain customary conditions. Accordingly, there can be no certainty, nor can the Corporation provide any assurance, that the Concurrent Offering will be completed. If the Concurrent Offering is not completed, the Corporation will not have all of the net proceeds that it requires to effect the expected use of proceeds from such offerings, see "Use of Proceeds". If the Concurrent Offering is not completed, Fortis could determine, including in the near term, to issue additional securities, including Common Shares, to fund its operations, see "— Future sales or issuances of securities of Fortis".

Future Sales or Issuances of Securities of Fortis

        We may issue additional securities to finance future activities outside of the Offering and the Concurrent Offering. We cannot predict the size of future issuances of securities or the effect, if any, that future issuances and sales of securities will have on the market price of the Common Shares. Sales or issuances of substantial numbers of Common Shares, or the expectation that such sales could occur, may adversely affect prevailing market prices of the Common Shares. In connection with any issuance of Common Shares, investors will suffer dilution to their voting power and we may experience dilution in our earnings per share.

Payment of Future Dividends

        Our Board of Directors reviews our financial performance quarterly and makes a determination of the appropriate level of dividends to be declared in the following quarter, if any. Currently, payment of dividends on our Common Shares is funded primarily from dividends we receive from our subsidiaries. Our subsidiaries are separate legal entities and have no independent obligation to pay dividends to us. Prior to paying dividends to us, the subsidiaries have financial obligations that must be satisfied, including, among others, their operating expenses and obligations to creditors. Furthermore, our utilities are required by regulation to maintain a minimum equity-to-total capital ratio that may restrict their ability to pay dividends to us or may require that we contribute capital to them. The future enactment of laws or regulations may prohibit or further restrict the ability of our subsidiaries to pay upstream dividends or to repay intercorporate indebtedness. In addition, in the event of a subsidiary's liquidation or reorganization, our right to participate in a distribution of assets is subject to the prior claims of the subsidiary's creditors. As a result, our ability to generate cash flow to pay dividends is reliant on the ability of our subsidiaries to generate sustained earnings and cash flows and to pay dividends.

CAPITALIZATION

        Upon completion of the Offering and the Concurrent Offering, there will be an aggregate of 21,097,728 additional Common Shares outstanding, or 22,824,228 additional Common Shares if the Over-Allotment Option is exercised in full (in each case on a non-diluted basis).

        The following table sets out the consolidated capitalization of the Corporation as at September 30, 2019 and on a pro forma basis, assuming the completion of the Concurrent Offering and no exercise of the Over-Allotment Option, as of such date after giving effect to (a) the receipt of the net proceeds of the Offering and the Concurrent Offering, determined after deducting the estimated expenses of the Offering and the

S-10

Table of Contents

Concurrent Offering, on an after tax basis, and the Underwriting Commission in connection with the Concurrent Offering, (b) the use of the net proceeds of the Offering and the Concurrent Offering to fund the Corporation's capital plan, repay indebtedness of the Corporation and for general corporate purposes, see "Use of Proceeds", and (c) the changes in Common Shares, long-term debt, capital lease and finance obligations from October 1, 2019 up to and including November 22, 2019. See "Changes in Consolidated Capitalization".

CHANGES IN CONSOLIDATED CAPITALIZATION

        The following describes the changes in our share and loan capital structure since September 30, 2019:

(a)

During the period from October 1, 2019 up to and including November 22, 2019, we issued an aggregate of 594,789 Common Shares as a result of (i) the sale of Common Shares pursuant to the ATM Distribution, and (ii) the exercise of options granted pursuant to our 2012 Stock Option Plan.



(b)

During the period from October 1, 2019 up to and including November 22, 2019, our consolidated long-term debt, capital lease and finance obligations, including current portions and committed credit facility borrowings classified as long-term debt increased by approximately $280 million, principally due to the issuance of US$100 million of long-term debt, the net increase in committed credit facility borrowings and changes in foreign exchange rates over the period.

S-11

Table of Contents

DESCRIPTION OF THE COMMON SHARES

        We are authorized to issue an unlimited number of Common Shares. See "Description of Securities Offered — Common Shares" in the Prospectus for a description of the material attributes and characteristics of the Common Shares. As of November 25, 2019, 438,872,038 Common Shares were issued and outstanding.

DIVIDEND POLICY

        Dividends on the Common Shares are declared at the discretion of our Board of Directors. We declared cumulative cash dividends on our Common Shares of $1.75 per Common Share in 2018, $1.65 per Common Share in 2017 and $1.55 per Common Share in 2016. On November 28, 2018, our Board of Directors declared a first quarter dividend of $0.45 per Common Share, which was paid on March 1, 2019 to holders of record on February 15, 2019. On February 14, 2019, our Board of Directors declared a second quarter dividend of $0.45 per Common Share, which was paid on June 1, 2019 to holders of record on May 17, 2019. On July 31, 2019, our Board of Directors announced a third quarter dividend of $0.45 per Common Share, which was paid on September 1, 2019 to holders of record on August 20, 2019. On September 10, 2019, our Board of Directors declared a fourth quarter dividend of $0.4775 per Common Share, which will be paid on December 1, 2019 to holders of record on November 19, 2019. On November 20, 2019, our Board of Directors declared a first quarter dividend for 2020 of $0.4775 per Common Share, which will be paid on March 1, 2020 to holders of record on February 18, 2020. We have increased our annual Common Share dividend payment for 46 consecutive years.

        Fortis is targeting average annual dividend growth of 6% through 2024. This dividend guidance takes into account many factors, including the expectation of reasonable outcomes for regulatory proceedings at the Fortis utilities, the successful execution of the Corporation's five-year capital plan and management's continued confidence in the strength of its diversified portfolio of utilities and record of operational excellence.

USE OF PROCEEDS

        The estimated net proceeds of the Offering are approximately $495 million. The estimated net proceeds of the Concurrent Offering are approximately $575 million, or approximately $662 million if the Over-Allotment Option is exercised in full. We intend to use the net proceeds from the Offering and the Concurrent Offering, if any, to fund the Corporation's capital plan, the repayment of indebtedness of the Corporation and for general corporate purposes. To the extent that the Corporation does not fully deploy the proceeds of the Offering and the Concurrent Offering immediately following closing, we may enter into hedging arrangements with one or more financial counterparties, including affiliates of one or more of the Underwriters, to hedge any currency risk relating to such retained proceeds.

        All expenses relating to the Offering will be paid out of the proceeds to the Corporation.

        The closing of the Offering under the Subscription Agreement is subject to customary conditions and the Closing Date is expected to occur on November 29, 2019, or such other date as may be agreed upon by us and the Subscribers, but not later than December 6, 2019. It is expected that the Corporation will arrange to electronically deposit the Offered Shares to or for the account of the Subscribers under the book-based system through DTC (or its nominee) on the Closing Date, against payment by the Subscribers to the Corporation of the aggregate purchase price for the Offered Shares. No certificate evidencing the Offered Shares will be issued to the Subscribers, unless otherwise agreed to by the Corporation and the Subscribers. In accordance with the

S-12

Table of Contents

book-based system, DTC will record a DTC participant as the registered owner of Offered Shares on behalf of the Subscribers. The Subscribers will receive only a customer confirmation from the registered dealer who is a DTC participant and through whom a beneficial interest in the Offered Shares is purchased.

        It is expected that delivery of the Offered Shares will be made against payment therefor on the Closing Date, which will not be two business days following the date of this Prospectus Supplement (this settlement cycle being referred to as T+2). Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in two business days, unless the parties to any such trade expressly agree otherwise.

        This Prospectus Supplement does not qualify the offering or issuance of Concurrent Offering Shares in the Concurrent Offering, the Over-Allotment Option or the offering or issuance of Additional Shares in the Over-Allotment Option. The Offering will be completed on the terms and conditions contained in the Subscription Agreement, and closing of the Offering may occur in circumstances where the Concurrent Offering is not completed.

        In connection with the Offering, the Corporation may distribute this Prospectus Supplement and the Prospectus electronically.

        The terms of the Offering and Offering Price of the Offered Shares were determined by negotiation between Fortis and the Subscribers. On closing, the Subscribers will receive the Commitment Fee equal to 1% of the gross proceeds of the Offering, being $5 million and have agreed not to dispose of the Offered Shares for a period of 45 days from the Closing Date. Fortis has not engaged the services of any underwriters in connection with the distribution of the Offered Shares hereunder. The expenses of the Offering are estimated to be $0.2 million and are payable by Fortis.

        The head office of each of the Subscribers purchasing the Offered Shares is located in New York, New York. The securities being offered under this Prospectus Supplement are registered in the U.S. under the Securities Act in accordance with MJDS.

Stock Exchange Listing

        We have applied to list the Offered Shares for trading on the TSX and the NYSE. The listing of the Offered Shares on the TSX and the NYSE will be subject to our fulfillment of all of the listing requirements of the TSX and the NYSE, respectively.

S-13

Table of Contents