Filed Pursuant to Rule 424(b)(5)
Registration No. 333-228342

The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and are not being used to solicit an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to Completion

Preliminary prospectus supplement dated November 28, 2018

PROSPECTUS SUPPLEMENT

(To prospectus dated November 13, 2018)

$650,000,000

Atmos Energy Corporation

Common stock

We are offering $500,000,000 of shares of our common stock in this offering. In addition, we expect to enter into separate forward sale agreements with each of Goldman Sachs & Co. LLC and Bank of America N.A. or their respective affiliates, whom we refer to as the forward counterparties, in respect of $150,000,000 of shares of our common stock. In connection with the forward sale agreements between us and the forward counterparties, the forward counterparties or their respective affiliates are, at our request, borrowing from third parties and selling to the underwriters an aggregate of $150,000,000 of shares of our common stock that will be delivered in this offering. If in its good faith and commercially reasonable judgment, a forward counterparty is unable to borrow and deliver for sale on the anticipated closing date the number of shares of our common stock underlying the applicable forward sale agreement, or such forward counterparty would be unable to borrow, at a stock loan rate not greater than a specified rate, and deliver for sale on the anticipated closing date such number of shares of our common stock, or if certain other conditions to such forward counterparty’s obligations have not been satisfied, then we will issue and sell directly to the underwriters a number of shares of our common stock equal to the number of shares that such forward counterparty does not borrow and deliver.

We expect to receive proceeds from the sale of $500,000,000 of shares of common stock offered and sold by us in this offering, but we will not initially receive any proceeds from the sale of $150,000,000 of shares of our common stock sold by the forward counterparties to the underwriters, except in certain circumstances described in this prospectus supplement, including the last sentence of the previous paragraph. We expect to settle the forward sale agreements and receive proceeds, subject to certain adjustments, from the sale of those shares of common stock assuming one or more future physical settlements of the forward sale agreements no later than approximately 16 months after the date of this prospectus supplement. Although we expect to settle the forward sale agreements entirely by the full physical delivery of shares of our common stock in exchange for cash proceeds, we may elect cash settlement or net share settlement for all or a portion of our obligations under the forward sale agreements. If we elect to cash settle or net share settle the forward sale agreements, we may not receive any proceeds from the issuance of shares, and we will instead receive or pay cash (in the case of cash settlement) or receive or deliver shares of our common stock (in the case of net share settlement). See “Underwriting (Conflicts of Interest)” for a description of the forward sale agreements.

Our common stock is listed on the New York Stock Exchange (the “NYSE”) under the symbol “ATO.” The last reported sales price of our common stock on November 27, 2018 was $98.42.

Investing in our common stock involves risks. See “Risk Factors” beginning on page S-9 of this prospectus supplement and page 3 of the accompanying prospectus.

The underwriters have agreed to purchase the shares of our common stock being offered hereby at a price of $                 per share, which will result in approximately $                 of aggregate net proceeds to us, before expenses, consisting of (1) $                 of estimated net proceeds, before expenses, to be received upon settlement of the shares common stock offered by us and (2) $                 of estimated net proceeds, before expenses, with respect to the shares of common stock to be offered by the forward counterparties. For the purpose of calculating the aggregate net proceeds to us, we have assumed that each forward sale agreement is physically settled on the effective date of the forward sale agreement based upon the initial forward sale price of $                 (which is the price at which the underwriters have agreed to buy the shares of common stock offered hereby). The forward sale price is subject to adjustment pursuant to the terms of each of the forward sale agreements, and the actual proceeds, if any, will be calculated as described in this prospectus supplement.

The underwriters may offer shares of our common stock from time to time for sale in one or more transactions on the NYSE, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. See “Underwriting (Conflicts of Interest).”

We have granted the underwriters an option to purchase up to an additional $97,500,000 of shares of our common stock, exercisable within 30 days from the date of this prospectus supplement. If such option is exercised, we may, in our sole discretion, enter into additional forward sale agreements with each of the forward counterparties in respect of the number of shares of our common stock that are subject to the exercise of such option, and we currently anticipate that, if such option is exercised, we will do so. Unless the context requires otherwise, the term “forward sale agreement” as used in this prospectus supplement includes any additional forward sale agreement that we elect to enter into in connection with the exercise by the underwriters of their option to purchase additional shares. In the event that we enter into any additional forward sale agreement, if in its good faith and commercially reasonable judgment, a forward counterparty is unable to borrow and deliver for sale on the anticipated closing date for the exercise of such option the number of shares of our common stock underlying the applicable forward sale agreement, or such forward counterparty would be unable to borrow, at a stock loan rate not greater than a specified rate, and deliver for sale on the anticipated closing date such number of shares of our common stock, or if certain other conditions to such forward counterparty’s obligations have not been satisfied, then we will issue and sell directly to the underwriters a number of shares of our common stock equal to the number of shares that such forward counterparty does not borrow and deliver.

Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement. Any representation to the contrary is a criminal offense.

The underwriters expect to deliver the shares on or about                 , 2018.

The date of this prospectus supplement is November     , 2018.

TABLE OF CONTENTS

Prospectus Supplement

Prospectus

IMPORTANT NOTICE ABOUT INFORMATION IN THIS PROSPECTUS SUPPLEMENT AND THE ACCOMPANYING PROSPECTUS

This document consists of two parts. The first part is this prospectus supplement, which describes the specific terms of this offering of our common stock and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference in this prospectus supplement and the accompanying prospectus. The second part is the accompanying prospectus, dated November 13, 2018, which gives more general information, some of which does not apply to this offering. To the extent there is a conflict between the information contained in this prospectus supplement, the information contained in the accompanying prospectus or the information contained in any document incorporated by reference herein or therein, the information contained in the most recent document shall control. This prospectus supplement and the accompanying prospectus are a part of a registration statement that we filed with the SEC using the SEC’s shelf registration rules.

We have not, and each of the underwriters and the forward counterparties have not, authorized any other person to provide you with information other than information provided or incorporated by reference in this prospectus supplement, the accompanying prospectus or any free writing prospectus relating to the offerings of common stock made pursuant to this prospectus supplement. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you or representations that others may make. See “Incorporation of Certain Documents by Reference” and “Where You Can Find More Information” in the accompanying prospectus.

Neither Atmos Energy Corporation nor the underwriters and the forward counterparties are making an offer of this common stock in any jurisdiction where the offer is not permitted.

The information contained in or incorporated by reference in this document is accurate only as of the date of this prospectus supplement or the date of such incorporated documents, regardless of the time of delivery of this prospectus supplement or of any sale of common stock. Our business, financial condition, results of operations and prospects may have changed since those respective dates.

The terms “we,” “our,” “us,” and “Atmos Energy” refer to Atmos Energy Corporation and its subsidiaries unless the context suggests otherwise. The term the “Company” refers to Atmos Energy Corporation and not its subsidiaries. The term “you” refers to a prospective investor.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

Statements contained or incorporated by reference in this prospectus supplement and the accompanying prospectus that are not statements of historical fact are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended. Forward-looking statements are based on management’s beliefs as well as assumptions made by, and information currently available to, management. Because such statements are based on expectations as to future results and are not statements of fact, actual results may differ materially from those stated. Important factors that could cause future results to differ include, but are not limited to:

All of these factors are difficult to predict and many are beyond our control. Accordingly, while we believe these forward-looking statements to be reasonable, there can be no assurance that they will approximate actual experience or that the expectations derived from them will be realized. When used in our documents or oral presentations, the words “anticipate,” “believe,” “estimate,” “expect,”

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“forecast,” “goal,” “intend,” “objective,” “plan,” “projection,” “seek,” “strategy” or similar words are intended to identify forward-looking statements. We undertake no obligation to update or revise any of our forward-looking statements, whether as a result of new information, future events or otherwise.

For additional factors you should consider, please see “Risk Factors” on page S-9 of this prospectus supplement, “Item 1A. Risk Factors” and “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the fiscal year ended September 30, 2018. See also “Incorporation of Certain Documents by Reference” in the accompanying prospectus.

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RISK FACTORS

Investing in our common stock involves risks. Our business is influenced by many factors that are difficult to predict and beyond our control and that involve uncertainties that may materially affect our results of operations, financial condition or cash flows, or the value of our common stock. These risks and uncertainties include those described below, as well as in the risk factors and other sections of the documents that are incorporated by reference in this prospectus supplement and the accompanying prospectus, including “Item 1A. Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended September 30, 2018. You should carefully consider these risks and uncertainties and all of the information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus before you invest in our common stock.

Settlement provisions contained in the forward sale agreements could result in substantial dilution to our earnings per share and return on equity or result in substantial cash payment obligations.

Each forward counterparty will have the right to accelerate the applicable forward sale agreement (with respect to a transaction under that particular forward sale agreement that the relevant forward counterparty determines is affected by such event) and require us to physically settle or, if we so elect and the forward counterparty permits our election, cash settle or net share settle on a date specified by the relevant forward counterparty if:

A forward counterparty’s decision to exercise its right to accelerate the settlement of a particular forward sale agreement will be made irrespective of our need for capital. In such cases, we could be required to issue and deliver shares of common stock under the physical settlement provisions of that particular forward sale agreement or, if we so elect and the forward counterparty permits our election,

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net share settlement provisions of that particular forward sale agreement irrespective of our capital needs, which would result in dilution to our earnings per share and return on equity.

We expect that settlement of the forward sale agreements will occur no later than March 31, 2020. However, any forward sale agreement may be settled earlier in whole or in part at our option. We expect that each forward sale agreement will be physically settled by delivery of shares of our common stock, unless we elect to cash settle or net share settle a particular forward sale agreement. Upon physical settlement or, if we so elect, net share settlement of a particular forward sale agreement, delivery of shares of our common stock in connection with such physical settlement or (to the extent we are obligated to deliver shares of our common stock) net share settlement will result in dilution to our earnings per share and return on equity. If we elect cash settlement or net share settlement with respect to all or a portion of the shares of common stock underlying a particular forward sale agreement, we expect that the relevant forward counterparty (or an affiliate thereof) will purchase a number of shares of common stock necessary to satisfy its or its affiliate’s obligation to return the shares of common stock borrowed from third parties in connection with sales of shares of our common stock related to that forward sale agreement. In addition, the purchase of shares of our common stock in connection with the relevant forward counterparty or its affiliate unwinding its hedge positions could cause the price of our common stock to increase over such time (or prevent a decrease over such time), thereby increasing the amount of cash we would owe to the relevant forward counterparty (or decreasing the amount of cash that the relevant forward counterparty would owe us) upon a cash settlement of the relevant forward sale agreement or increasing the number of shares of common stock we would deliver to the relevant forward counterparty (or decreasing the number of shares of common stock that the relevant forward counterparty would deliver to us) upon net share settlement of the relevant forward sale agreement.

The forward sale price that we expect to receive upon physical settlement of a particular forward sale agreement will be subject to adjustment on a daily basis based on a floating interest rate factor equal to the federal funds rate less a spread and will be decreased based on amounts related to expected dividends on our common stock during the term of the particular forward sale agreement. If the federal funds rate is less than the spread on any day, the interest factor will result in a daily reduction of the applicable forward sale price. If the market value of our common stock during the relevant valuation period under the particular forward sale agreement is above the applicable forward sale price, in the case of cash settlement, we would pay the relevant forward counterparty under that particular forward sale agreement an amount in cash equal to the difference or, in the case of net share settlement, we would deliver to the relevant forward counterparty a number of shares of common stock having a value equal to the difference. Thus, we could be responsible for a potentially substantial cash payment in the case of cash settlement of a particular forward sale agreement. See “Underwriting (Conflicts of Interest)” for information on the forward sale agreements.

In case of our bankruptcy or insolvency, any forward sale agreements will automatically terminate, and we would not receive the expected proceeds from any forward sales of our common stock.

If we file for or consent to a proceeding seeking a judgment in bankruptcy or insolvency or any other relief under any bankruptcy or insolvency law or other similar law affecting creditors’ rights, or we or a regulatory authority with jurisdiction over us presents a petition for our winding-up or liquidation, and we consent to such a petition, any forward sale agreements that are then in effect will automatically terminate. If any such forward sale agreement so terminates under these circumstances, we would not be obligated to deliver to the relevant forward counterparty any of our common stock not previously delivered, and the relevant forward counterparty would be discharged from its obligation to pay the applicable forward sale price per share in respect of any of our common stock not previously settled under the applicable forward sale agreement. Therefore, to the extent that there are any shares

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of our common stock with respect to which any forward sale agreement has not been settled at the time of the commencement of any such bankruptcy or insolvency proceedings, we would not receive the relevant forward sale price per share in respect of those shares of our common stock.

This offering may cause the price of our common stock to decline.

The issuance of new shares of common stock in this offering could have the effect of depressing the market price for shares of our common stock.

There may be future sales or other dilution of our equity, which may materially adversely affect the market price for shares of our common stock.

We are generally not restricted from issuing additional shares of common stock, including any securities that are convertible into or exchangeable for, or that represent the right to receive shares of common stock or any substantially similar securities. The market price for shares of our common stock could materially decline as a result of sales of shares of common stock or similar securities in the market made after such offering or the perception that such sales could occur.

The price and trading volume of our common stock may fluctuate significantly, and you could lose all or part of your investment.

The market price of our common stock on the New York Stock Exchange constantly changes and we expect that will continue. In the future, such market price may become highly volatile and subject to wide fluctuations due to our future performance or external factors. In addition, the trading volume of our common stock may fluctuate and cause significant price variations to occur. Volatility in the market price of our common stock may prevent you from being able to sell your shares at or above the price you paid for your shares of common stock. The market price for our common stock could fluctuate significantly for various reasons, including:

In recent years, the stock market has experienced significant price and volume fluctuations. This volatility frequently has occurred without regard to the operating performance of the affected companies. Hence, the price of our common stock could fluctuate based upon factors that have little or nothing to do with us, and these fluctuations could materially reduce our share price.

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All of our debt obligations have priority over shares of our common stock, which would subordinate your rights to payment as a holder of our common stock in the event of a liquidation, dissolution or winding up.

In any liquidation, dissolution or winding up of Atmos Energy, shares of our common stock would rank below all debt claims against Atmos Energy. As a result, holders of shares of our common stock would not be entitled to receive any payment or other distribution of assets upon the liquidation, dissolution or winding up of Atmos Energy until after our obligations to our debt holders have been satisfied.

Although we have paid cash dividends on shares of our common stock in the past, we may not pay cash dividends or increase our dividends on shares of our common stock in the future.

Holders of shares of our common stock are entitled to receive only such dividends as our Board of Directors may declare out of funds legally available for such purpose. We have a history of paying dividends to our shareholders when sufficient cash is available. However, future cash dividends will depend upon our results of operations, financial condition, cash requirements, the need to maintain adequate capital levels or increase our dividends and other factors. Also, the amount of cash dividends that may be paid on our common stock is restricted by provisions contained in certain debt agreements. There can be no assurance that we will continue to pay dividends or increase our dividends even if the necessary financial conditions are met and if sufficient cash is available for distribution.

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USE OF PROCEEDS

We estimate that the net proceeds that we receive from the sale of the common stock we are offering and selling, after deducting the underwriting discount and commissions and before expenses payable by us, will be approximately $         million. We will not initially receive any proceeds from the sale of shares of our common stock by the forward counterparties or their affiliates, unless an event occurs that requires us to sell our common stock to the underwriters in lieu of a forward counterparty borrowing and delivering shares of our common stock to the underwriters, in which case we intend to use all net proceeds we receive from such sale for the same purposes described below. We currently anticipate that if the underwriters exercise their option to purchase additional shares, we will request that the forward counterparties borrow such additional shares from third parties and sell such shares to the underwriters, and that we will enter into additional forward sale agreements with the forward counterparties in connection therewith.

At an initial forward sale price of $         per share (which is the price at which the underwriters have agreed to buy the shares of common stock offered hereby), we expect to receive net proceeds, before expenses, of approximately $         million (or approximately $         million if the underwriters’ option to purchase additional shares of our common stock is exercised in full), subject to the price adjustment and other provisions of the forward sale agreements, in the event of full physical settlement of the forward sale agreements, which settlement must occur within approximately 16 months of the date of this prospectus supplement. For purposes of calculating the proceeds to us upon settlement of the forward sale agreements, we have assumed that each forward sale agreement is physically settled based upon the initial forward sale price of $                 (which is the price at which the underwriters have agreed to buy the shares of common stock offered hereby) on the effective date of the forward sale agreements, which will be                 , 2018. The actual proceeds from the forward sales are subject to the final settlement of the forward sale agreements. The forward sale price that we expect to receive upon physical settlement of the forward sale agreements will be subject to adjustment on a daily basis based on a floating interest rate factor equal to the federal funds rate less a spread and will be decreased on each of certain dates specified in each forward sale agreement during the term of such forward sale agreement. The forward sale price will also be subject to decrease if the cost to the forward counterparty of borrowing a number of shares of our common stock underlying the forward sale agreement exceeds a specified amount. If the federal funds rate is less than the spread on any day, the interest factor will result in a daily reduction of the forward sale price. See “Underwriting (Conflicts of Interest)—Forward Sale Agreements” for a description of the forward sale agreements.

We intend to use the net proceeds we receive upon the issuance and sale of shares of our common stock to repay short-term debt under our commercial paper program, to fund capital spending primarily to enhance the safety and reliability of our system and for general corporate purposes. We use our commercial paper program to fund ongoing working capital needs, such as our seasonal requirements for gas supply, general corporate liquidity and capital expenditures. At November 27, 2018, we had approximately $235 million in principal amount of short-term debt outstanding under our commercial paper program, with a weighted average interest rate of 2.34% and a weighted average maturity of 5 days.

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BUSINESS

Overview

Atmos Energy Corporation, headquartered in Dallas, Texas, and incorporated in Texas and Virginia, is one of the country’s largest natural-gas-only distributors based on number of customers. We deliver natural gas through regulated sales and transportation arrangements to over three million residential, commercial, public authority and industrial customers in eight states located primarily in the South. We also operate one of the largest intrastate pipelines in Texas based on miles of pipe.

Operating Segments

We manage and review our consolidated operations through the following three reportable segments:

Distribution Segment Overview

Our distribution segment is primarily comprised of our regulated natural gas distribution and related sales operations in eight states. The following table summarizes key information about our six regulated natural gas distribution divisions, presented in order of total rate base.

We operate in our service areas under terms of non-exclusive franchise agreements granted by the various cities and towns that we serve. At September 30, 2018, we held 1,013 franchises having terms generally ranging from five to 35 years. A significant number of our franchises expire each year, which require renewal prior to the end of their terms. Historically, we have successfully renewed these franchises and believe that we will continue to be able to renew our franchises as they expire.

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Revenues in this operating segment are established by regulatory authorities in the states in which we operate. These rates are intended to be sufficient to cover the costs of conducting business, including a reasonable return on invested capital. In addition, we transport natural gas for others through our distribution systems.

Rates established by regulatory authorities often include cost adjustment mechanisms for costs that (i) are subject to significant price fluctuations compared to our other costs, (ii) represent a large component of our cost of service and (iii) are generally outside our control.

Purchased gas cost adjustment mechanisms represent a common form of cost adjustment mechanism. Purchased gas cost adjustment mechanisms provide natural gas distribution companies a method of recovering purchased gas costs on an ongoing basis without filing a rate case because they provide a dollar-for-dollar offset to increases or decreases in the cost of natural gas. Therefore, although substantially all of our natural gas distribution operating revenues fluctuate with the cost of gas that we purchase, distribution Contribution Margin (a Non-GAAP measure defined as operating revenues less purchased gas cost) is generally not affected by fluctuations in the cost of gas.

Additionally, some jurisdictions have performance-based ratemaking adjustments that provide incentives to distribution companies to minimize purchased gas costs through improved storage management and use of financial instruments to lock in gas costs. Under the performance-based ratemaking adjustments, purchased gas costs savings are shared between the utility and its customers.

Our rate strategy focuses on reducing or eliminating regulatory lag, obtaining adequate returns and providing stable, predictable margins, which benefit both our customers and the Company. As a result of our ratemaking efforts in recent years, Atmos Energy has:

Pipeline and Storage Segment Overview

Our pipeline and storage segment consists of the pipeline and storage operations of our Atmos Pipeline—Texas Division (“APT”) and our natural gas transmission operations in Louisiana. APT is one of the largest intrastate pipeline operations in Texas with a heavy concentration in the established natural gas-producing areas of central, northern and eastern Texas, extending into or near the major producing areas of the Barnett Shale, the Texas Gulf Coast and the Delaware and Val Verde Basins of West Texas. Through its system, APT provides transportation and storage services to our Mid-Tex Division, other third party local distribution companies, industrial and electric generation customers, marketers and producers. As part of its pipeline operations, APT owns and operates five underground storage reservoirs in Texas.

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Revenues earned from transportation and storage services for APT are subject to traditional ratemaking governed by the Railroad Commission of Texas. Rates are updated through periodic filings made under Texas’ Gas Reliability Infrastructure Program (“GRIP”). GRIP allows us to include in our rate base annually approved capital costs incurred in the prior calendar year provided that we file a complete rate case at least once every five years. APT’s existing regulatory mechanisms allow certain transportation and storage services to be provided under market-based rates.

Our natural gas transmission operations in Louisiana are comprised of a proprietary 21-mile pipeline located in New Orleans, Louisiana that is primarily used to aggregate gas supply for our distribution division in Louisiana under a long-term contract and, on a more limited basis, to third parties. The demand fee charged to our Louisiana distribution division for these services is subject to regulatory approval by the Louisiana Public Service Commission. We also manage two asset management plans in Louisiana with distribution affiliates of the Company, which have been approved by applicable state regulatory commissions. Generally, these asset management plans require us to share with our distribution customers a significant portion of the cost savings earned from these arrangements.

Natural Gas Marketing Segment Overview

Through December 31, 2016, we were engaged in a nonregulated natural gas marketing business, which was conducted by AEM. AEM’s primary business was to aggregate and purchase gas supply, arrange transportation and storage logistics and ultimately deliver gas to customers at competitive prices. Following the sale of AEM, effective January 1, 2017, we have fully exited the nonregulated natural gas marketing business.

Other Regulation

We are regulated by various state or local public utility authorities. We are also subject to regulation by the United States Department of Transportation with respect to safety requirements in the operation and maintenance of our transmission and distribution facilities. In addition, our operations are also subject to various state and federal laws regulating environmental matters. From time to time we receive inquiries regarding various environmental matters. We believe that our properties and operations substantially comply with, and are operated in substantial conformity with, applicable safety and environmental statutes and regulations. There are no administrative or judicial proceedings arising under environmental quality statutes pending or known to be contemplated by governmental agencies which would have a material adverse effect on us or our operations. Our environmental claims have arisen primarily from former manufactured gas plant sites. The Pipeline and Hazardous Materials Safety Administration (PHMSA), within the U.S. Department of Transportation, develops and enforces the regulations for the safe, reliable and environmentally sound operation of the pipeline transportation system. The PHMSA pipeline safety statutes provide for states to assume safety authority over intrastate and natural gas pipelines. State pipeline safety programs are responsible for adopting and enforcing the federal and state pipeline safety regulations for intrastate natural gas transmission and distribution pipelines.

The Federal Energy Regulatory Commission (“FERC”) allows, pursuant to Section 311 of the Natural Gas Policy Act, gas transportation services through our Atmos Pipeline—Texas assets “on behalf of” interstate pipelines or local distribution companies served by interstate pipelines, without subjecting these assets to the jurisdiction of the FERC. Additionally, the FERC has regulatory authority over the sale of natural gas in the wholesale gas market and the use and release of interstate pipeline and storage capacity. The FERC also has authority to detect and prevent market manipulation and to enforce compliance with FERC’s other rules, policies and orders by companies engaged in the sale, purchase, transportation or storage of natural gas in interstate commerce. We have taken what we believe are the necessary and appropriate steps to comply with these regulations.

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Competition

Although our regulated distribution operations are not currently in significant direct competition with any other distributors of natural gas to residential and commercial customers within our service areas, we do compete with other natural gas suppliers and suppliers of alternative fuels for sales to industrial customers. We compete in all aspects of our business with alternative energy sources, including, in particular, electricity. Electric utilities offer electricity as a rival energy source and compete for the space heating, water heating and cooking markets. Promotional incentives, improved equipment efficiencies and promotional rates all contribute to the acceptability of electrical equipment. The principal means to compete against alternative fuels is lower prices, and natural gas historically has maintained its price advantage in the residential, commercial and industrial markets.

Our pipeline and storage operations historically faced competition from other existing intrastate pipelines seeking to provide or arrange transportation, storage and other services for customers. In the last few years, several new pipelines have been completed, which has increased the level of competition in this segment of our business.

Distribution, Transmission and Related Assets

At September 30, 2018, in our distribution segment, we owned an aggregate of 70,071 miles of underground distribution and transmission mains throughout our distribution systems. These mains are located on easements or rights-of-way. We maintain our mains through a program of continuous inspection and repair and believe that our system of mains is in good condition. Through our pipeline and storage segment we owned 5,678 miles of gas transmission lines as well.

Storage Assets

We own underground gas storage facilities in several states to supplement the supply of natural gas in periods of peak demand. At September 30, 2018, the underground gas storage facilities of our distribution segment had a total usable capacity of 13,103,562 Mcf and a maximum daily delivery capacity of 234,100 Mcf, with the underground gas storage facilities of our pipeline and storage segment having a total usable capacity of 46,494,589 Mcf and a maximum daily delivery capacity of 1,766,000 Mcf.

Additionally, we contract for storage service in underground storage facilities on many of the interstate pipelines serving us to supplement our proprietary storage capacity. The amount of our contracted storage capacity can vary from time to time. At September 30, 2018, we had contracted storage capacity as follows: (i) distribution segment—maximum quantity of 32,425,245 MMBtu and a maximum daily withdrawal quantity of 1,088,167 MMBtu and (ii) pipeline and storage segment—maximum storage quantity of 1,000,000 MMBtu and a maximum daily withdrawal quantity of 47,500 MMBtu.

For more information on our storage assets, see “Item 2. Properties” in our Annual Report on Form 10-K for the fiscal year ended September 30, 2018.

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CERTAIN U.S. FEDERAL INCOME TAX CONSIDERATIONS FOR NON-U.S. HOLDERS

The following is a general discussion of certain U.S. federal income tax considerations with respect to the ownership and disposition of shares of our common stock applicable to non-U.S. Holders who acquire such shares in this offering and hold such shares as a capital asset (generally, property held for investment). For purposes of this discussion, a “non-U.S. Holder” generally means a beneficial owner of our common stock that is not, for U.S. federal income tax purposes, any of the following:

This discussion is based on current provisions of the Internal Revenue Code of 1986, as amended from time to time (the “Code”), Treasury regulations promulgated thereunder, judicial opinions, published positions of the Internal Revenue Service (the “IRS”), and other applicable authorities, all of which are subject to change (possibly with retroactive effect). This discussion does not address all aspects of U.S. federal income taxation that may be important to a particular non-U.S. Holder in light of that non-U.S. Holder’s individual circumstances, including Medicare taxes imposed on net investment income and the alternative minimum tax, nor does it address any aspect of U.S. federal estate and gift, state, local, or non-U.S. taxes. This discussion may not apply, in whole or in part, to particular non-U.S. Holders in light of their individual circumstances or to holders subject to special treatment under the U.S. federal income tax laws, such as:

If a partnership (or other entity or arrangement treated as a partnership for U.S. federal income tax purposes) holds our common stock, the tax treatment of a partner will generally depend on the status of the partner and the activities of the partnership. Partners of a partnership holding our common stock should consult their tax adviser as to the particular U.S. federal income tax consequences applicable to them.

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We have not sought, and will not seek, any ruling from the IRS or any opinion of counsel with respect to the tax consequences discussed herein, and there can be no assurance that the IRS will not take a position contrary to the tax consequences discussed below or that any position taken by the IRS would not be sustained.

EACH NON-U.S. HOLDER IS STRONGLY URGED TO CONSULT ITS TAX ADVISER REGARDING THE U.S. FEDERAL, STATE, LOCAL, AND NON-U.S. INCOME AND OTHER TAX CONSEQUENCES OF ACQUIRING, HOLDING AND DISPOSING OF OUR COMMON STOCK.

Dividends

In general, any distributions we make to a non-U.S. Holder with respect to its shares of our common stock that constitute dividends for U.S. federal income tax purposes will be subject to U.S. withholding tax at a rate of 30% of the gross amount, unless the non-U.S. Holder is eligible for a reduced rate of withholding tax under an applicable tax treaty and the non-U.S. Holder provides proper certification of its eligibility for such reduced rate (including providing a valid IRS Form W-8BEN or W-8BEN-E (or other applicable documentation)). A distribution will constitute a dividend for U.S. federal income tax purposes to the extent of our current or accumulated earnings and profits as determined for U.S. federal income tax purposes. Any distribution not constituting a dividend will be treated first as reducing the adjusted basis in the non-U.S. Holder’s shares of our common stock and, to the extent it exceeds the adjusted basis in the non-U.S. Holder’s shares of our common stock, as gain from the sale or exchange of such stock.

Dividends we pay to a non-U.S. Holder that are effectively connected with its conduct of a trade or business within the United States (and, if required by an applicable tax treaty, are attributable to a U.S. permanent establishment of such non-U.S. Holder) will not be subject to U.S. withholding tax, as described above, if the non-U.S. Holder complies with applicable certification and disclosure requirements (including providing a valid IRS Form W-8ECI). Instead, such dividends generally will be subject to U.S. federal income tax on a net income basis, in the same manner as if the non-U.S. Holder were a resident of the United States. Dividends received by a foreign corporation that are effectively connected with its conduct of a trade or business within the United States may also be subject to an additional branch profits tax at a rate of 30% (or such lower rate as may be specified by an applicable tax treaty).

Any distributions we make to a non-U.S. Holder with respect to its shares of our common stock will also be subject to the rules discussed below under the headings “Backup Withholding, Information Reporting and Other Reporting Requirements” and “Foreign Account Tax Compliance Act.”

Gain on Sale or Other Disposition of Common Stock

In general, a non-U.S. Holder will not be subject to U.S. federal income tax on any gain realized upon the sale or other disposition of the non-U.S. Holder’s shares of our common stock unless:

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Gain that is effectively connected with the conduct of a trade or business in the United States (or so treated) will generally be subject to U.S. federal income tax, net of certain deductions, at regular U.S. federal income tax rates. If the non-U.S. Holder is a foreign corporation, the branch profits tax described above also may apply to such effectively connected gain. An individual non-U.S. Holder who is subject to U.S. federal income tax because the non-U.S. Holder was present in the United States for 183 days or more during the year of sale or other disposition of our common stock will generally be subject to a flat 30% tax on the gain derived from such sale or other disposition, which may be offset by U.S.-source capital losses (assuming certain requirements are met, including timely filing of U.S. federal income tax returns with respect to such losses). Non-U.S. Holders should consult their tax advisers regarding the application of these rules to them, including if we are or become a USRPHC. Any sale or other disposition with respect to a non-U.S. Holder’s shares of our common stock will also be subject to the rules discussed below under the headings “Backup Withholding, Information Reporting and Other Reporting Requirements” and “Foreign Account Tax Compliance Act.”

Backup Withholding, Information Reporting and Other Reporting Requirements

We must report annually to the IRS, and to each non-U.S. Holder, the amount of dividends paid to, and the tax withheld with respect to, each non-U.S. Holder. These reporting requirements apply regardless of whether withholding was reduced or eliminated by an applicable tax treaty. Copies of this information reporting may also be made available under the provisions of a specific tax treaty or agreement with the tax authorities in the country in which the non-U.S. Holder resides or is established.

A non-U.S. Holder will generally be subject to backup withholding for dividends on our common stock paid to such holder (at the applicable rate), unless such non-U.S. Holder certifies under penalties of perjury that, among other things, it is a non-U.S. Holder (and the payor does not have actual knowledge or reason to know that such holder is a U.S. person), and otherwise complies with all applicable legal requirements.

Information reporting and backup withholding generally are not required with respect to the amount of any proceeds from the sale or other disposition of our common stock by a non-U.S. Holder outside the United States through a foreign office of a foreign broker that does not have certain specified connections to the United States. However, if a non-U.S. Holder sells or otherwise disposes its shares of our common stock through a U.S. broker or the U.S. office of a foreign broker, the broker will generally be required to report the amount of proceeds paid to the non-U.S. Holder to the IRS and also backup withhold on that amount, unless such non-U.S. Holder provides appropriate certification to the broker of its status as a non-U.S. person or otherwise establishes an exemption (and the payor does not have actual knowledge or reason to know that such holder is a U.S. person). Information reporting will also apply if a non-U.S. Holder sells its shares of our common stock through a foreign broker deriving more than a specified percentage of its income from U.S. sources or having certain other connections to the United States, unless such broker has documentary evidence in its records that such non-U.S. Holder is a non-U.S. person and certain other conditions are met, or such non-U.S. Holder otherwise establishes an exemption (and the payor does not have actual knowledge or reason to know that such holder is a U.S. person).

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Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. Holder can be credited against the non-U.S. Holder’s U.S. federal income tax liability, if any, or refunded, provided that the required information is furnished to the IRS in a timely manner. Non-U.S. Holders should consult their tax advisers regarding the application of the information reporting and backup withholding rules to them.

Foreign Account Tax Compliance Act

Withholding taxes may be imposed under Sections 1471 to 1474 of the Code, the Treasury regulations promulgated thereunder and other official guidance (commonly referred to as “FATCA”) on certain types of payments made to non-U.S. financial institutions and certain other non-U.S. entities. Specifically, a 30% withholding tax may be imposed on dividends on, or gross proceeds from the sale or other disposition of, our common stock paid to a “foreign financial institution” or a “non-financial foreign entity” (each as defined in the Code), unless those entities comply with certain requirements under the Code and applicable Treasury regulations, which requirements may be modified by an “intergovernmental agreement” entered into between the United States and an applicable foreign country. Future Treasury regulations or other official guidance may modify these requirements.

Under the applicable Treasury regulations, withholding under FATCA generally applies to payments of dividends on our common stock and the IRS has announced that withholding will apply to payments of gross proceeds from the sale or other disposition of such stock on or after January 1, 2019. The FATCA withholding tax will apply to all withholdable payments without regard to whether the beneficial owner of the payment would otherwise be entitled to an exemption from imposition of withholding tax pursuant to an applicable tax treaty with the United States or U.S. domestic law. Prospective investors should consult their tax advisers regarding the potential application of withholding under FATCA to their investment in our common stock.

The U.S. federal tax discussion set forth above is included for general information only and may not be applicable depending upon a particular non-U.S. Holder’s particular situation. Holders should consult their tax advisers with respect to the tax consequences to them of the purchase, ownership and disposition of the stock, including the tax consequences under state, local, foreign and other tax laws and the possible effects of changes in U.S. federal or other tax laws.

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UNDERWRITING (CONFLICTS OF INTEREST)

In this offering, subject to the terms and conditions of the underwriting agreement, we have agreed to sell $500,000,000 of shares of our common stock to the underwriters, and the forward counterparties have agreed, at our request, to borrow from third parties and sell to the underwriters $150,000,000 of shares of our common stock in connection with the execution of forward sale agreements between us and each of Goldman Sachs & Co. LLC and Bank of America, N.A., whom we refer to in such capacity as the forward counterparties. Subject to the terms and conditions of the underwriting agreement among us, the forward counterparties and the underwriters, we and the forward counterparties have agreed to sell to the underwriters named below, and the underwriters named below have severally agreed to purchase from us and the forward counterparties, the number of shares of our common stock listed opposite their names below:

The underwriters have agreed to purchase all of the shares of common stock sold under the underwriting agreement if they purchase any shares. The underwriting agreement provides that the obligations of the underwriters to purchase the shares included in this offering are subject to approval of legal matters by counsel and to other conditions contained in the underwriting agreement.

We have agreed to indemnify the several underwriters against, or contribute to payments that the underwriters may be required to make in respect of, certain liabilities, including liabilities under the Securities Act of 1933, as amended (the “Securities Act”).

The underwriters propose to offer the shares of common stock offered hereby from time to time for sale in one or more transactions on the NYSE, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices, subject to receipt and acceptance by them and subject to their right to reject any order in whole or in part. The underwriters may effect such transactions by selling the shares of common stock to or through dealers and such dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or purchasers of shares of common stock for whom they may act as agents or to whom they may sell as principal. The difference between the price at which the underwriters purchase shares and the price at which the underwriters resell such shares may be deemed underwriting compensation.

Forward Sale Agreements

We expect to enter into forward sale agreements on the date of this prospectus supplement with the forward counterparties relating to an aggregate of $150,000,000 of shares of our common stock. In connection with the execution of the forward sale agreements, and at our request, the forward counterparties are borrowing from third parties and selling in this offering an aggregate of $150,000,000 of shares of our common stock.

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If in the good faith and commercially reasonable judgment of a forward counterparty, (i) it or its affiliate is unable to borrow and deliver for sale on the anticipated closing date of the offering the full number of shares of our common stock underlying the applicable forward sale agreement, or (ii) it or its affiliate is unable to borrow, at a stock loan rate not greater than a specified rate, and deliver for sale on the anticipated closing date of the offering the full number of shares of our common stock underlying the applicable forward sale agreement, then the number of shares of our common stock to which such forward sale agreement relates will be reduced to the number that such forward counterparty can so borrow and deliver, which may be zero. In the event that the number of shares of our common stock to which one or more of the forward sale agreements relate is so reduced, the commitments of the several underwriters to purchase shares of our common stock from the forward counterparties and the forward counterparties’ obligation to borrow such shares for delivery and sale to the several underwriters, as described above, will be replaced with the commitments to purchase from us and our corresponding obligation to issue directly to the underwriters, severally in proportion to their respective underwriting obligations reflected in the table above, all or such portion of the number of shares of our common stock not borrowed and delivered by the forward counterparties. In such event, we or the representatives of the underwriters will have the right to postpone the closing date for up to two business days to effect any necessary changes to the documents or arrangements in connection with such closing.

We will receive an amount equal to the net proceeds from the sale of the borrowed shares of our common stock sold in this offering, subject to certain adjustments pursuant to the forward sale agreements, from the forward counterparties upon physical settlement of the forward sale agreements. We will only receive such proceeds if we elect to physically settle the forward sale agreements.

The forward sale agreements provide for settlement on a settlement date or dates to be specified at our discretion, but which we expect to occur on or prior to March 31, 2020. On a settlement date or dates, if we decide to physically settle one or more forward sale agreements, we will issue shares of our common stock to the relevant forward counterparty at the then-applicable forward sale price. The forward sale price will initially be $                per share, which is the price at which the underwriters have agreed to buy the shares of common stock offered hereby. The forward sale agreements provide that the initial forward sale price will be subject to adjustment based on a floating interest rate factor equal to the federal funds rate less a spread, and will be subject to decrease on each of certain dates specified in the forward sale agreements by amounts related to expected dividends on shares of our common stock during the term of the forward sale agreements. The forward sale price will also be subject to decrease if the cost to the forward seller of borrowing a number of shares of our common stock underlying the forward sale agreement exceeds a specified amount. If the federal funds rate is less than the spread on any day, the interest rate factor will result in a daily reduction of the forward sale price.

Before the issuance of shares of our common stock, if any, upon physical or net share settlement of the forward sale agreements, we expect that the shares issuable upon settlement of the forward sale agreements will be reflected in our diluted earnings per share calculation using the treasury stock method. Under this method, the number of shares of our common stock used in calculating diluted earnings per share is deemed to be increased by the excess, if any, of the number of shares of our common stock that would be issued upon full physical settlement of the forward sale agreements over the number of shares of common stock that could be purchased by us in the market (based on the average market price of our common stock during the applicable reporting period) using the proceeds receivable upon full physical settlement (based on the adjusted forward sale price at the end of the

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reporting period). Consequently, we anticipate there will be no dilutive effect on our earnings per share except during periods when the average market price of shares of our common stock is above the applicable adjusted forward sale price, which is initially $                 per share, subject to increase or decrease based on the federal funds rate, less a spread, and subject to decrease by amounts related to expected dividends on shares of our common stock during the term of the forward sale agreements. However, if we decide to physically settle or net share settle the forward sale agreements, delivery of shares of our common stock to the forward counterparties on any such physical settlement or net share settlement of the forward sale agreements would result in dilution to our earnings per share.

Each forward counterparty will have the right to accelerate that particular forward sale agreement (with respect to a transaction under that particular forward sale agreement that the relevant forward counterparty determines is affected by such event) and require us to physically settle or, if we so elect and the forward counterparty permits our election, cash settle or net share settle on a date specified by the relevant forward counterparty if:

A forward counterparty’s decision to exercise its right to accelerate the settlement of a particular forward sale agreement will be made irrespective of our need for capital. In such cases, we could be required to issue and deliver shares of common stock under the physical settlement provisions of that particular forward sale agreement or, if we so elect and the forward counterparty permits our election, net share settlement provisions of that particular forward sale agreement irrespective of our capital needs, which would result in dilution to our earnings per share and return on equity. In addition, upon certain events of bankruptcy or insolvency related to us, each forward sale agreement will automatically terminate without further liability of either party. Following any such termination, we would not issue any shares of common stock or receive any proceeds pursuant to the forward sale agreements.

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Each forward sale agreement will be physically settled, unless we elect to settle such forward sale agreement in cash or to net share settle such forward sale agreement (which we have the right to do, subject to certain conditions, other than in the limited circumstances described above). If we decide to physically settle or net share settle a forward sale agreement, delivery of shares of our common stock upon any physical settlement or net share settlement of the forward sale agreement will result in dilution to our earnings per share. If we elect cash or net share settlement for all or a portion of the shares of our common stock underlying a forward sale agreement, we would expect the relevant forward counterparty or one of its affiliates to repurchase a number of shares of our common stock equal to the portion for which we elect cash or net share settlement in order to satisfy its obligation to return the shares of our common stock such forward counterparty had borrowed in connection with sales of our common stock under this prospectus supplement and, if applicable in connection with net share settlement, to deliver shares of our common stock to us. If the market value of our common stock at the time of such purchase is above the forward sale price at that time, we will pay or deliver, as the case may be, to the relevant forward counterparty under its forward sale agreement, an amount in cash, or a number of shares of our common stock with a market value, equal to such difference. Any such difference could be significant. Conversely, if the market value of our common stock at the time of such purchase is below the forward sale price at that time, such forward counterparty will pay or deliver, as the case may be, to us under its forward sale agreement, an amount in cash, or a number of shares of our common stock with a market value, equal to such difference.

In addition, the purchase of shares of our common stock by a forward counterparty or its affiliate to unwind such forward counterparty’s hedge position could cause the market price of our common stock to increase over time, thereby increasing the amount of cash we would owe to a forward counterparty upon a cash settlement or increasing the number of shares of our common stock we would owe to a forward counterparty upon a net share settlement, as the case may be, of its forward sale agreement, or decreasing the amount of cash that a forward counterparty would owe us upon a cash settlement or decreasing the number of shares of our common stock that a forward counterparty would owe us upon a net share settlement, as the case may be, of its forward sale agreement. We will not be able to control the manner in which the forward counterparties unwind their hedge positions.

The foregoing is a description of certain provisions of the forward sale agreements we expect to enter into in connection with this offering, copies of which are available upon request from us at the address set forth in the section of the accompanying prospectus entitled “Where You Can Find More Information.” This description of certain terms of the forward sale agreements is not complete and is subject to, and qualified in its entirety by reference to, the provisions of those agreements.

Option to Purchase Additional Shares

We have granted the underwriters an option for a period of 30 days from the date of this prospectus supplement to purchase up to an additional $97,500,000 of shares of our common stock at a price of $                 per share. If such option is exercised, we may, in our sole discretion, enter into additional forward sale agreements with each of the forward counterparties in respect of the number of shares of our common stock that are subject to the exercise of such option, and we currently anticipate that, if such option is exercised, we will do so. If such option is exercised and we elect not to enter into additional forward sale agreements, we have agreed to issue and sell directly to the underwriters the number of shares of our common stock that are subject to the exercise of such option. In the event that we enter into any additional forward sale agreement, if in its good faith and commercially reasonable judgment, a forward counterparty or its affiliate is unable to borrow and deliver for sale on the anticipated closing date for the exercise of such option the number of shares of our common stock underlying the applicable forward sale agreement, or such forward counterparty would be unable to borrow, at a stock loan rate not greater than a specified rate, and deliver for sale on the anticipated closing date such number of shares of our common stock, or if certain other conditions to such forward

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counterparty’s obligations have not been satisfied, then we will issue and sell directly to the underwriters a number of shares of our common stock equal to the number of shares that such forward counterparty does not borrow and deliver.

Lock-Ups

We and all of our directors and executive officers have agreed, subject to certain exceptions, for a period of 90 days after the date of this prospectus supplement, to not, without the prior written consent of the underwriters, (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, or otherwise transfer or dispose of, directly or indirectly, or cause to be filed with the SEC a registration statement under the Securities Act relating to, any shares of common stock or any securities convertible into or exercisable or exchangeable for common stock, or publicly disclose the intention to make any offer, sale, pledge or disposition, (2) enter into any swap or other agreement that transfers, in whole or in part, any of the economic consequences of ownership of the common stock or such other securities, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of common stock or such other securities, in cash or otherwise. The foregoing restrictions do not apply, in our case, to the issuance of the common stock in this offering; any common stock issuable upon the exercise of options, or upon the vesting of restricted stock units, granted under our equity incentive plans (as existing on the date hereof); restricted stock unit awards under our equity incentive plans; and common stock issued pursuant to our Direct Stock Purchase Plan, 1998 Long-Term Incentive Plan and our Retirement Savings Plan and Trust. The foregoing restrictions also do not apply, with respect to our directors and executive officers, to withholding of shares by the Company for the purpose of covering tax liabilities related to vesting of restricted stock unit awards during the 90-day period and to transfers of shares as gifts, by will or the laws of intestacy, or pursuant to domestic relations or court orders.

Price Stabilization and Short Positions

In connection with this offering, the underwriters may engage in stabilizing transactions, which involves making bids for, purchasing and selling shares of common stock in the open market for the purpose of preventing or retarding a decline in the market price of the common stock while this offering is in progress. These stabilizing transactions may include making short sales of the common stock, which involves the sale by the underwriters of a greater number of shares of common stock than they are required to purchase in this offering, and purchasing shares of common stock on the open market to cover positions created by short sales. The underwriters may close out any short position by purchasing shares in the open market. A short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the common stock in the open market that could adversely affect investors who purchase in this offering. To the extent that the underwriters create a short position, they will purchase shares in the open market to cover the position.

The underwriters have advised us that, pursuant to Regulation M of the Securities Act of 1933, they may also engage in other activities that stabilize, maintain or otherwise affect the price of the common stock, including the imposition of penalty bids. This means that if the underwriters purchase common stock in the open market in stabilizing transactions or to cover short sales the underwriters that sold those shares as part of this offering may be required to repay the underwriting discount received by them.

These activities may have the effect of raising or maintaining the market price of the common stock or preventing or retarding a decline in the market price of the common stock, and, as a result, the price of the common stock may be higher than the price that otherwise might exist in the open market. If the underwriters commence these activities, they may discontinue them at any time. The

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underwriters may carry out these transactions on the New York Stock Exchange, in the over the counter market or otherwise.

Certain Relationships

The underwriters and their respective affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory investment management, investment research, principal investment, hedging, financing and brokerage activities. In the ordinary course of business, certain of the underwriters or their respective affiliates have provided and may in the future provide commercial, financial advisory or investment banking services for us and our subsidiaries for which they have received or will receive customary compensation. For example, affiliates of certain of the underwriters are lenders under our revolving credit facilities and dealers under our commercial paper program. To the extent we use the proceeds from this offering to repay any indebtedness under our commercial paper program, such affiliates of certain underwriters will receive a portion of the proceeds from this offering.

In the ordinary course of their various business activities, the underwriters and their respective affiliates have made or held, and may in the future make or hold, a broad array of investments including serving as counterparties to certain derivative and hedging arrangements, and may have actively traded, and, in the future may actively trade, debt and equity securities (or related derivative securities), and financial instruments (including bank loans) for their own account and for the accounts of their customers and may have in the past and at any time in the future hold long and short positions in such securities and instruments. Such investment and securities activities may have involved, and in the future may involve, securities and instruments of us or our subsidiaries. The underwriters and their respective affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

Conflicts of Interest

All of the proceeds from the sale of shares of our common stock offered by the forward counterparties in this offering (excluding proceeds, if any, paid to us with respect to any shares of common stock that we may sell to the underwriters in lieu of the forward counterparties selling such shares as further described elsewhere in this prospectus supplement) will be paid to the forward counterparties. Because Goldman Sachs & Co. LLC and Merrill Lynch, Pierce, Fenner & Smith Incorporated, or their affiliates, in their capacity as forward purchasers, will receive more than 5% of the net proceeds of this offering, Goldman Sachs & Co. LLC and Merrill Lynch, Pierce, Fenner & Smith Incorporated are deemed to have a conflict of interest within the meaning of FINRA Rule 5121. Accordingly, this offering will be conducted in compliance with the applicable provisions of FINRA Rule 5121. Pursuant to that rule, the appointment of a “qualified independent underwriter” is not required in connection with this offering, as the shares of common stock have a “bona fide public market” (as defined in FINRA Rule 5121).

Electronic Prospectus Delivery

A prospectus supplement and accompanying base prospectus in electronic format may be made available on the web sites maintained by one or more underwriters, or selling group members, if any, participating in the offering. The underwriters may agree to allocate a number of shares to underwriters and selling group members for sale to their online brokerage account holders. Internet distributions will be allocated by the underwriters and selling group members that may make Internet distributions on the same basis as other allocations.

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Selling Restrictions

Other than in the United States, no action has been taken by us or the underwriters that would permit a public offering of the shares of common stock offered by this prospectus supplement in any jurisdiction where action for that purpose is required. The shares of common stock offered by this prospectus supplement may not be offered or sold, directly or indirectly, nor may this prospectus supplement or any other offering material or advertisements in connection with the offer and sale of any such of common stock be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus supplement comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus supplement. This prospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any shares of common stock offered by this prospectus supplement in any jurisdiction in which such an offer or a solicitation is unlawful.

European Economic Area

In relation to each member state of the European Economic Area (each, a “Member State”), no offer of shares of common stock that are the subject of the offering has been, or will be made to the public in that Member State, other than under the following exemptions under the Prospectus Directive:

provided that no such offer of shares of common stock referred to in (a) to (c) above shall result in a requirement for the Company or any underwriter to publish a prospectus pursuant to Article 3 of the Prospectus Directive, or supplement a prospectus pursuant to Article 16 of the Prospectus Directive.

Each person located in a Member State to whom any offer of shares of common stock is made or who receives any communication in respect of an offer of shares of common stock, or who initially acquires any shares of common stock will be deemed to have represented, warranted, acknowledged and agreed to and with each underwriter and the Company that (1) it is a “qualified investor” within the meaning of the law in that Member State implementing Article 2(1)(e) of the Prospectus Directive; and (2) in the case of any shares of common stock acquired by it as a financial intermediary as that term is used in Article 3(2) of the Prospectus Directive, the shares of common stock acquired by it in the offer have not been acquired on behalf of, nor have they been acquired with a view to their offer or resale to, persons in any Member State other than qualified investors, as that term is defined in the Prospectus Directive, or in circumstances in which the prior consent of the underwriters has been given to the offer or resale; or where shares of common stock have been acquired by it on behalf of persons in any Member State other than qualified investors, the offer of those shares of common stock to it is not treated under the Prospectus Directive as having been made to such persons.

The Company, the underwriters and their respective affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgments and agreements.

This prospectus supplement has been prepared on the basis that any offer of shares of common stock in any Member State will be made pursuant to an exemption under the Prospectus Directive from the requirement to publish a prospectus for offers of shares. Accordingly any person making or

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intending to make an offer in that Member State of shares of common stock that are the subject of the offering contemplated in this prospectus supplement may only do so in circumstances in which no obligation arises for the Company or any of the underwriters to publish a prospectus pursuant to Article 3 of the Prospectus Directive in relation to such offer. Neither the Company nor the underwriters have authorized, nor do they authorize, the making of any offer of shares of common stock in circumstances in which an obligation arises for the Company or the underwriters to publish a prospectus for such offer.

For the purposes of this provision, the expression an “offer of shares of common stock to the public” in relation to any shares of common stock in any Member State means the communication in any form and by any means of sufficient information on the terms of the offer and the shares of common stock to be offered so as to enable an investor to decide to purchase or subscribe the shares of common stock, as the same may be varied in that Member State by any measure implementing the Prospectus Directive in that Member State, the expression “Prospectus Directive” means Directive 2003/71/EC (as amended) and includes any relevant implementing measure in each Member State.

The above selling restriction is in addition to any other selling restrictions set out below.

United Kingdom

In addition, in the United Kingdom, this document is being distributed only to, and is directed only at, and any offer subsequently made may only be directed at, persons who are “qualified investors” (as defined in the Prospectus Directive) (i) who have professional experience in matters relating to investments falling within Article 19 (5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the “Order”) and/or (ii) who are high net worth companies (or persons to whom it may otherwise be lawfully communicated) falling within Article 49(2)(a) to (d) of the Order (all such persons together being referred to as “relevant persons”). This document must not be acted on or relied on in the United Kingdom by persons who are not relevant persons. In the United Kingdom, any investment or investment activity to which this document relates is only available to, and will be engaged in with, relevant persons.

Australia

No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission (“ASIC”), in relation to the offering. This prospectus supplement does not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001 (the “Corporations Act”), and does not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.

Any offer in Australia of the shares of common stock may only be made to persons (the “Exempt Investors”) who are “sophisticated investors” (within the meaning of section 708(8) of the Corporations Act), “professional investors” (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act so that it is lawful to offer the shares of common stock without disclosure to investors under Chapter 6D of the Corporations Act.

The shares of common stock applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under the offering, except in circumstances where disclosure to investors under Chapter 6D of the Corporations Act would not be required pursuant to an exemption under section 708 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapter 6D of the Corporations Act. Any person acquiring shares of common stock must observe such Australian on-sale restrictions.

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This prospectus supplement contains general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus supplement is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

Bermuda

Shares of common stock may be offered or sold in Bermuda only in compliance with the provisions of the Investment Business Act of 2003 of Bermuda which regulates the sale of securities in Bermuda. Additionally, non-Bermudian persons (including companies) may not carry on or engage in any trade or business in Bermuda unless such persons are permitted to do so under applicable Bermuda legislation.

British Virgin Islands

The shares of common stock may be offered to persons located in the British Virgin Islands who are “qualified investors” for the purposes of the Securities and Investment Business Act, 2010 (“SIBA”). Qualified investors include (i) certain entities which are regulated by the Financial Services Commission in the British Virgin Islands, including banks, insurance companies, licensees under SIBA and public, professional and private mutual funds; (ii) a company, any securities of which are listed on a recognised exchange; and (iii) persons defined as “professional investors” under SIBA, which is any person (a) whose ordinary business involves, whether for that person’s own account or the account of others, the acquisition or disposal of property of the same kind as the property, or a substantial part of the property of the Company; or (b) who has signed a declaration that he, whether individually or jointly with his spouse, has net worth in excess of US$1,000,000 and that he consents to being treated as a professional investor.

Canada

The shares of common stock may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the shares of common stock must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 (or, in the case of securities issued or guaranteed by the government of a non-Canadian jurisdiction, section 3A.4) of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

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China

This prospectus supplement does not constitute a public offer of shares of common stock, whether by sale or subscription, in the People’s Republic of China (the “PRC”). The shares of common stock are not being offered or sold directly or indirectly in the PRC to or for the benefit of, legal or natural persons of the PRC.

Further, no legal or natural persons of the PRC may directly or indirectly purchase any of the shares of common stock or any beneficial interest therein without obtaining all prior PRC’s governmental approvals that are required, whether statutorily or otherwise. Persons who come into possession of this document are required by the Company and its representatives to observe these restrictions.

Dubai International Financial Centre

This prospectus supplement relates to an Exempt Offer in accordance with the Offered Securities Rules of the Dubai Financial Services Authority (“DFSA”). This prospectus supplement is intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement nor taken steps to verify the information set forth herein and has no responsibility for the prospectus supplement. The shares of common stock to which this prospectus supplement relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the shares of common stock offered should conduct their own due diligence on the shares of common stock. If you do not understand the contents of this prospectus supplement you should consult an authorized financial advisor.

Hong Kong

The shares of common stock have not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than (a) to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong and any rules made under that Ordinance; or (b) in other circumstances which do not result in the document being a “prospectus” as defined in the Companies Ordinance (Cap. 32) of Hong Kong or which do not constitute an offer to the public within the meaning of that Ordinance. No advertisement, invitation or document relating to the shares of common stock has been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to shares of common stock which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the Securities and Futures Ordinance and any rules made under that Ordinance.

Japan

The shares of common stock have not been and will not be registered under the Financial Instruments and Exchange Law of Japan (Law No. 25 of 1948, as amended) and, accordingly, will not be offered or sold, directly or indirectly, in Japan, or for the benefit of any Japanese Person or to others for re-offering or resale, directly or indirectly, in Japan or to any Japanese Person, except in compliance with all applicable laws, regulations and ministerial guidelines promulgated by relevant Japanese governmental or regulatory authorities in effect at the relevant time. For the purposes of this paragraph, “Japanese Person” shall mean any person resident in Japan, including any corporation or other entity organized under the laws of Japan.

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Korea

The shares of common stock have not been and will not be registered under the Financial Investments Services and Capital Markets Act of Korea and the decrees and regulations thereunder (the “FSCMA”), and the shares of common stock have been and will be offered in Korea as a private placement under the FSCMA. None of the shares of common stock may be offered, sold or delivered directly or indirectly, or offered or sold to any person for re-offering or resale, directly or indirectly, in Korea or to any resident of Korea except pursuant to the applicable laws and regulations of Korea, including the FSCMA and the Foreign Exchange Transaction Law of Korea and the decrees and regulations thereunder (the “FETL”). Furthermore, the purchaser of the shares of common stock shall comply with all applicable regulatory requirements (including but not limited to requirements under the FETL) in connection with the purchase of the shares of common stock. By the purchase of the shares of common stock, the relevant holder thereof will be deemed to represent and warrant that if it is in Korea or is a resident of Korea, it purchased the shares of common stock pursuant to the applicable laws and regulations of Korea.

Malaysia

No prospectus or other offering material or document in connection with the offer and sale of the shares of common stock has been or will be registered with the Securities Commission of Malaysia (“Commission”) for the Commission’s approval pursuant to the Capital Markets and Services Act 2007. Accordingly, this prospectus supplement and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the shares of common stock may not be circulated or distributed, nor may the shares of common stock be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Malaysia other than (i) a closed end fund approved by the Commission; (ii) a holder of a Capital Markets Services Licence; (iii) a person who acquires the shares of common stock, as principal, if the offer is on terms that the shares of common stock may only be acquired at a consideration of not less than RM250,000 (or its equivalent in foreign currencies) for each transaction; (iv) an individual whose total net personal assets or total net joint assets with his or her spouse exceeds RM3 million (or its equivalent in foreign currencies), excluding the value of the primary residence of the individual; (v) an individual who has a gross annual income exceeding RM300,000 (or its equivalent in foreign currencies) per annum in the preceding twelve months; (vi) an individual who, jointly with his or her spouse, has a gross annual income of RM400,000 (or its equivalent in foreign currencies), per annum in the preceding twelve months; (vii) a corporation with total net assets exceeding RM10 million (or its equivalent in a foreign currencies) based on the last audited accounts; (viii) a partnership with total net assets exceeding RM10 million (or its equivalent in foreign currencies); (ix) a bank licensee or insurance licensee as defined in the Labuan Financial Services and Securities Act 2010; (x) an Islamic bank licensee or takaful licensee as defined in the Labuan Financial Services and Securities Act 2010; and (xi) any other person as may be specified by the Commission; provided that, in the each of the preceding categories (i) to (xi), the distribution of the shares of common stock is made by a holder of a Capital Markets Services License who carries on the business of dealing in securities. The distribution in Malaysia of this prospectus supplement is subject to Malaysian laws. This prospectus supplement does not constitute and may not be used for the purpose of public offering or an issue, offer for subscription or purchase, invitation to subscribe for or purchase any securities requiring the registration of a prospectus with the Commission under the Capital Markets and Services Act 2007.

Saudi Arabia

This document may not be distributed in the Kingdom of Saudi Arabia except to such persons as are permitted under the Offers of Securities Regulations as issued by the board of the Saudi Arabian Capital Market Authority (“CMA”) pursuant to resolution number 2-11-2004 dated 4 October 2004 as

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amended by resolution number 1-28-2008, as amended (the “CMA Regulations”). The CMA does not make any representation as to the accuracy or completeness of this document and expressly disclaims any liability whatsoever for any loss arising from, or incurred in reliance upon, any part of this document. Prospective purchasers of the securities offered hereby should conduct their own due diligence on the accuracy of the information relating to the securities. If you do not understand the contents of this document, you should consult an authorized financial adviser.

Singapore

This prospectus supplement has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of shares of common stock may not be circulated or distributed, nor may the shares of common stock be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the “SFA”), (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to Section 275(1A), and in accordance with the conditions specified in Section 275, of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

Where the shares of common stock are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

securities (as defined in Section 239(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the shares of common stock pursuant to an offer made under Section 275 of the SFA except:

South Africa

Due to restrictions under the securities laws of South Africa, the shares of common stock are not offered, and the offer shall not be transferred, sold, renounced or delivered, in South Africa or to a person with an address in South Africa, unless one or other of the following exemptions applies:

(i) the offer, transfer, sale, renunciation or delivery is to duly registered banks, mutual banks, financial services provider, financial institution, the Public Investment Corporation (in each case

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registered as such in South Africa), a person who deals with securities in their ordinary course of business, or a wholly owned subsidiary of a bank, mutual bank, authorized services provider or financial institution, acting as agent in the capacity of an authorized portfolio manager for a pension fund (duly registered in South Africa), or as manager for a collective investment scheme (registered in South Africa); or

(ii) the contemplated acquisition cost of the securities, for any single addressee acting as principal is equal to or greater than R1,000,000.

This prospectus supplement does not, nor is it intended to, constitute an “offer to the public” (as that term is defined in the South African Companies Act, 2008, or the SA Companies Act, and does not, nor is it intended to, constitute a prospectus prepared and registered under the SA Companies Act. This document is not an “offer to the public” and must not be acted on or relied on by persons who do not fall within Section 96(1)(a) of the SA Companies Act (such persons being referred to as “relevant persons”). Any investment or investment activity to which this document relates is available only to relevant persons and will be engaged in only with relevant persons.

Switzerland

The shares of common stock may not be publicly offered in Switzerland and will not be listed on the SIX Swiss Exchange (“SIX”) or on any other stock exchange or regulated trading facility in Switzerland. This document has been prepared without regard to the disclosure standards for issuance prospectuses under art. 652a or art. 1156 of the Swiss Code of Obligations or the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading facility in Switzerland. Neither this document nor any other offering or marketing material relating to the shares of common stock or the offering may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this document nor any other offering or marketing material relating to the offering, the Company, the shares of common stock have been or will be filed with or approved by any Swiss regulatory authority. In particular, this document will not be filed with, and the offer of shares of common stock will not be supervised by, the Swiss Financial Market Supervisory Authority (FINMA), and the offer of shares of common stock has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes (“CISA”). The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to acquirers of shares of common stock.

Taiwan

The shares of common stock have not been and will not be registered with the Financial Supervisory Commission of Taiwan pursuant to relevant securities laws and regulations and may not be sold, issued or offered within Taiwan through a public offering or in circumstances which constitutes an offer within the meaning of the Securities and Exchange Act of Taiwan that requires a registration or approval of the Financial Supervisory Commission of Taiwan. No person or entity in Taiwan has been authorized to offer, sell, give advice regarding or otherwise intermediate the offering and sale of the shares of common stock in Taiwan.

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United Arab Emirates

The shares of common stock have not been, and are not being, publicly offered, sold, promoted or advertised in the United Arab Emirates (including the Dubai International Financial Centre) other than in compliance with the laws of the United Arab Emirates (and the Dubai International Financial Centre) governing the issue, offering and sale of securities. Further, this prospectus supplement does not constitute a public offer of securities in the United Arab Emirates (including the Dubai International Financial Centre) and is not intended to be a public offer. This prospectus supplement has not been approved by or filed with the Central Bank of the United Arab Emirates, the Securities and Commodities Authority or the Dubai Financial Services Authority.

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LEGAL MATTERS

The validity of the shares of common stock offered hereby will be passed upon for us by Gibson, Dunn & Crutcher LLP and Hunton Andrews Kurth LLP. Certain legal matters in connection with this offering will be passed upon for the underwriters by Shearman & Sterling LLP, New York, New York.

EXPERTS

The consolidated financial statements of Atmos Energy Corporation appearing in Atmos Energy Corporation’s Annual Report (Form 10-K) for the year ended September 30, 2018 (including the schedule appearing therein), and the effectiveness of Atmos Energy Corporation’s internal control over financial reporting as of September 30, 2018 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

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INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” information in this prospectus supplement or the accompanying base prospectus that we have filed with the SEC. This means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is considered to be part of this prospectus supplement and the accompanying base prospectus, except for any information that is superseded by information that is included directly in this prospectus supplement or the accompanying base prospectus relating to an offering of our securities.

We incorporate by reference into this prospectus supplement the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, prior to the termination of this offering of securities. These additional documents include periodic reports, such as annual reports on Form 10-K and quarterly reports on Form 10-Q, and current reports on Form 8-K (other than information furnished under Items 2.02 and 7.01 or corresponding information furnished under Item 9.01 as an exhibit, which is deemed not to be incorporated by reference in this prospectus supplement), as well as proxy statements (other than information identified in them as not incorporated by reference). You should review these filings as they may disclose a change in our business, prospects, financial condition or other affairs after the date of this prospectus supplement.

This prospectus supplement incorporates by reference the documents listed below that we have filed with the SEC but have not been included or delivered with this document:

These documents contain important information about us and our financial condition.

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You may obtain a copy of any of these filings, or any of our future filings, from us without charge by requesting it in writing or by telephone at the following address or telephone number:

Atmos Energy Corporation

1800 Three Lincoln Centre

5430 LBJ Freeway

Dallas, Texas 75240

Attention: Jennifer Hills

(972) 934-9227

Our website is www.atmosenergy.com; any information on or connected to our website is not part of this prospectus supplement.

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PROSPECTUS

Atmos Energy Corporation

By this prospectus, we offer up to

$3,000,000,000

of debt securities and common stock.

We will provide specific terms of these securities in supplements to this prospectus. This prospectus may not be used to sell securities unless accompanied by a prospectus supplement. You should read this prospectus and the applicable prospectus supplement carefully before you invest.

Investing in these securities involves risks. See “Risk Factors” on page 3 of this prospectus, in the applicable prospectus supplement and in the documents incorporated by reference.

Our common stock is listed on the New York Stock Exchange under the symbol “ATO.”

Our address is 1800 Three Lincoln Centre, 5430 LBJ Freeway, Dallas, Texas 75240, and our telephone number is (972) 934-9227.

The Securities and Exchange Commission and state securities regulators have not approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

This prospectus is dated November 13, 2018

We have not authorized any other person to provide you with any information or to make any representation that is different from, or in addition to, the information and representations contained in this prospectus or in any of the documents that are incorporated by reference in this prospectus. We take no responsibility for, and can provide no assurances as to the reliability of, any other information that others may give you or representations that others may make. We are not making or soliciting an offer of any securities other than the securities described in this prospectus and any prospectus supplement. You should assume that the information appearing in this prospectus, as well as the information contained in any document incorporated by reference, is accurate as of the date of each such document only, unless the information specifically indicates that another date applies.

TABLE OF CONTENTS

The distribution of this prospectus may be restricted by law in certain jurisdictions. You should inform yourself about and observe any of these restrictions. This prospectus does not constitute, and may not be used in connection with, an offer or solicitation by anyone in any jurisdiction in which the offer or solicitation is not authorized, or in which the person making the offer or solicitation is not qualified to do so, or to any person to whom it is unlawful to make the offer or solicitation.

The terms “we,” “our,” “us,” and “Atmos Energy” refer to Atmos Energy Corporation and its subsidiaries unless the context suggests otherwise. The term “you” refers to a prospective investor.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

Statements contained or incorporated by reference in this prospectus that are not statements of historical fact are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”). Forward-looking statements are based on management’s beliefs as well as assumptions made by, and information currently available to, management. Because such statements are based on expectations as to future results and are not statements of fact, actual results may differ materially from those stated. Important factors that could cause future results to differ include, but are not limited to:

All of these factors are difficult to predict and many are beyond our control. Accordingly, while we believe our forward-looking statements to be reasonable, there can be no assurance that they will approximate actual experience or that the expectations derived from them will be realized. When used in our documents or oral presentations, the words “anticipate,” “believe,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “objective,” “plan,” “projection,” “seek,” “strategy” or similar words are intended to identify forward-looking statements. We undertake no obligation to update or revise any of our forward-looking statements, whether as a result of new information, future events or otherwise.

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For additional factors you should consider generally and when evaluating these forward-looking statements, please see “Risk Factors” below, “Item 1A. Risk Factors” and “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the fiscal year ended September 30, 2018. See also “Incorporation of Certain Documents by Reference” on page 25 of this prospectus, as well as the applicable prospectus supplement.

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RISK FACTORS

Investing in our debt securities or our common stock involves risks. Our business is influenced by many factors that are difficult to predict and beyond our control and that involve uncertainties that may materially affect our results of operations, financial condition or cash flows, or the value of these securities. These risks and uncertainties include those described in the risk factors and other sections of the documents that are incorporated by reference in this prospectus. Subsequent prospectus supplements may contain a discussion of additional risks applicable to an investment in us and the particular type of securities we are offering under the prospectus supplements. You should carefully consider all of the information contained in or incorporated by reference in this prospectus or in the applicable prospectus supplement before you invest in our debt securities or common stock.

ATMOS ENERGY CORPORATION

Atmos Energy Corporation, headquartered in Dallas, Texas, and incorporated in Texas and Virginia, is one of the country’s largest natural-gas-only distributors based on number of customers. We deliver natural gas through regulated sales and transportation arrangements to over three million residential, commercial, public authority and industrial customers in eight states located primarily in the South. We also operate one of the largest intrastate pipelines in Texas based on miles of pipe.

We manage and review our consolidated operations through the following three reportable segments:

SECURITIES WE MAY OFFER

Types of Securities

The types of securities that we may offer and sell from time to time by this prospectus are:

The aggregate initial offering price of all securities sold will not exceed $3,000,000,000. We will determine when we sell securities, the amounts of securities we will sell and the prices and other terms on which we will sell them. We may sell securities to or through underwriters, through agents or dealers or directly to purchasers. The offer and sale of securities by this prospectus is subject to receipt of satisfactory regulatory approvals in three states, all of which have been received and are currently in effect.

Prospectus Supplements

This prospectus provides you with a general description of the debt securities and common stock we may offer. Each time we offer securities, we will provide a prospectus supplement that will contain specific information about the terms of the offering. The prospectus supplement may also add to or change information contained in this prospectus. In that case, the prospectus supplement should be read as superseding this prospectus.

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In each prospectus supplement, which will be attached to the front of this prospectus, we will include, among other things, the following information:

For more details on the terms of the securities, you should read the exhibits filed with our registration statement, of which this prospectus is a part. You should also read both this prospectus and the applicable prospectus supplement, together with additional information described under the heading “Where You Can Find More Information.”

USE OF PROCEEDS

Except as may otherwise be stated in the applicable prospectus supplement, we intend to use the net proceeds from the sale of the securities that we may offer and sell from time to time by this prospectus for general corporate purposes, including for working capital, repaying indebtedness and funding capital projects and other growth.

DESCRIPTION OF DEBT SECURITIES

We may issue debt securities from time to time in one or more distinct series. This section summarizes the material terms that we anticipate will be common to all series of debt securities. Please note that the terms of any series of debt securities that we may offer may differ significantly from the common terms described in this prospectus. Many of the other terms of any series of debt securities that we offer, and any differences from the common terms described in this prospectus, will be described in the prospectus supplement for such securities to be attached to the front of this prospectus.

As required by U.S. federal law for all bonds and notes of companies that are publicly offered, a document called an indenture will govern any debt securities that we issue. An indenture is a contract between us and a financial institution acting as trustee on behalf of the purchasers of the debt securities. We have entered into an indenture with U.S. Bank National Association, as trustee (the “indenture”), which is subject to the Trust Indenture Act of 1939. The trustee under the indenture has the following two main roles:

As this section is a summary of some of the terms of the debt securities we may offer under this prospectus, it does not describe every aspect of the debt securities. We urge you to read the indenture and the other

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documents we file with the SEC relating to the debt securities because the indenture for those securities and those other documents, and not this description, will define your rights as a holder of our debt securities. We filed a copy of the indenture with the SEC as an exhibit to our Current Report on Form 8-K filed March 26, 2009, and it is incorporated in this prospectus by reference. We may file any such other documents as exhibits to an annual, quarterly or current report that we file with the SEC following their execution. See “Where You Can Find More Information” for information on how to obtain copies of the indenture and any such other documents. References to the “indenture” mean the indenture that will define your rights as a holder of debt securities. Capitalized terms used in this section and not otherwise defined have the meanings set forth in the indenture.

General

The debt securities will be our unsecured obligations. Senior debt securities will rank equally with all of our other unsecured and unsubordinated indebtedness. Subordinated debt securities will rank junior to our senior indebtedness, including our credit facilities.

You should read the prospectus supplement that will describe the following terms of the series of debt securities offered by the prospectus supplement:

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For purposes of this prospectus, any reference to the payment of principal of, any premium on, or interest on the debt securities will include Additional Amounts if required by the terms of the debt securities.

The indenture does not limit the amount of debt securities that we are authorized to issue from time to time. The indenture also provides that there may be multiple series of debt securities issued thereunder and more than one trustee thereunder, each for one or more series of debt securities. If a trustee is acting under the indenture with respect to more than one series of debt securities, the debt securities for which it is acting would be treated as if issued under separate indentures. If there is more than one trustee under the indenture, the powers and trust obligations of each trustee will apply only to the debt securities of the separate series for which it is trustee.

We may issue debt securities with terms different from those of debt securities already issued. Without the consent of the holders of the outstanding debt securities, we may reopen a previous issue of a series of debt securities and issue additional debt securities of that series unless the reopening was restricted when we created that series.

There is no requirement that we issue debt securities in the future under the indenture, and we may use other indentures or documentation, containing different provisions in connection with future issues of other debt securities.

We may issue the debt securities as “original issue discount securities,” which are debt securities, including any zero-coupon debt securities, that are issued and sold at a discount from their stated principal amount. Original issue discount securities provide that, upon acceleration of their maturity, an amount less than their principal amount will become due and payable. We will describe the U.S. federal income tax consequences and other considerations applicable to original issue discount securities in any prospectus supplement relating to them.

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Holders of Debt Securities

Book-Entry Holders. We will issue debt securities in book-entry form only, unless we specify otherwise in the applicable prospectus supplement. This means the debt securities will be represented by one or more global securities registered in the name of a financial institution that holds them as depository on behalf of other financial institutions that participate in the depository’s book-entry system. These participating institutions, in turn, hold beneficial interests in the debt securities on behalf of themselves or their customers.

Under the indenture, we will recognize as a holder only the person in whose name a debt security is registered. Consequently, for debt securities issued in global form, we will recognize only the depository as the holder of the debt securities and we will make all payments on the debt securities to the depository. The depository passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depository and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the debt securities. As a result, you will not own the debt securities directly. Instead, you will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depository’s book-entry system or holds an interest through a participant. As long as the debt securities are issued in global form, you will be an indirect holder, and not a holder, of the debt securities.

Street Name Holders. In the future we may terminate a global security or issue debt securities initially in non-global form. In these cases, you may choose to hold your debt securities in your own name or in “street name.” Debt securities held in street name would be registered in the name of a bank, broker or other financial institution that you choose, and you would hold only a beneficial interest in those debt securities through an account you maintain at that institution.

For debt securities held in street name, we will recognize only the intermediary banks, brokers and other financial institutions in whose names the debt securities are registered as the holders of those debt securities, and we will make all payments on those debt securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. If you hold debt securities in street name you will be an indirect holder, and not a holder, of those debt securities.

Legal Holders. Our obligations, as well as the obligations of the trustee and those of any third parties employed by us or the trustee, run only to the legal holders of the debt securities. We do not have obligations to you if you hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether you choose to be an indirect holder of a debt security or have no choice because we are issuing the debt securities only in global form.

For example, once we make a payment or give a notice to the holder, we have no further responsibility for the payment or notice, even if that holder is required, under agreements with depository participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, if we want to obtain the approval of the holders for any purpose (for example, to amend the indenture or to relieve us of the consequences of a default or of our obligation to comply with a particular provision of the indenture) we would seek the approval only from the holders, and not the indirect holders, of the debt securities. Whether and how the holders contact the indirect holders is up to the holders.

When we refer to you, we mean those who invest in the debt securities being offered by this prospectus, whether they are the holders or only indirect holders of those debt securities. When we refer to your debt securities, we mean the debt securities in which you hold a direct or indirect interest.

Special Considerations for Indirect Holders. If you hold debt securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

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Global Securities

What is a Global Security? We will issue each debt security under the indenture in book-entry form only, unless we specify otherwise in the applicable prospectus supplement. A global security represents one or any other number of individual debt securities. Generally, all debt securities represented by the same global securities will have the same terms. We may, however, issue a global security that represents multiple debt securities that have different terms and are issued at different times. We call this kind of global security a master global security.

Each debt security issued in book-entry form will be represented by a global security that we deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depository. Unless we specify otherwise in the applicable prospectus supplement, The Depository Trust Company, New York, New York, known as DTC, will be the depository for all debt securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depository or its nominee, unless special termination situations arise. We describe those situations below under “Special Situations When a Global Security Will Be Terminated.” As a result of these arrangements, the depository, or its nominee, will be the sole registered owner and holder of all debt securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depository or with another institution that does. Thus, if your security is represented by a global security, you will not be a holder of the debt security, but only an indirect holder of a beneficial interest in the global security.

Special Considerations for Global Securities. We do not recognize an indirect holder as a holder of debt securities and instead deal only with the depository that holds the global security. The account rules of your financial institution and of the depository, as well as general laws relating to securities transfers, will govern your rights relating to a global security.

If we issue debt securities only in the form of a global security, you should be aware of the following:

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Special Situations When a Global Security Will Be Terminated. In a few special situations described below, a global security will be terminated and interests in it will be exchanged for certificates in non-global form representing the debt securities it represented. After that exchange, you will be able to choose whether to hold the debt securities directly or in street name. You must consult your own bank or broker to find out how to have your interests in a global security transferred on termination to your own name, so that you will be a holder. We have described the rights of holders and street name investors above under “Holders of Debt Securities.”

The special situations for termination of a global security are as follows:

If a global security is terminated, only the depository, and not we or the trustee, is responsible for deciding the names of the intermediary banks, brokers and other financial institutions in whose names the debt securities represented by the global security are registered, and, therefore, who will be the holders of those debt securities.

Covenants

This section summarizes the material covenants in the indenture. Please refer to the applicable prospectus supplement for information about any changes to our covenants, including any addition or deletion of a covenant, and to the indenture for information on other covenants not described in this prospectus or the applicable prospectus supplement.

Limitations on Liens. We covenant in the indenture that we will not, and will not permit any of our Restricted Subsidiaries to, create, incur, issue or assume any Indebtedness secured by any Lien on any Principal Property, or on shares of stock or Indebtedness of any Restricted Subsidiary, known as Restricted Securities, without making effective provision for the Outstanding Securities, other than debt securities of any series not entitled to the benefit of this covenant, to be secured by a Lien equally and ratably with, or prior to (or in the case of debt securities of any series that are subordinated in right of payment to the Indebtedness secured by such

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Lien, by a Lien subordinated to), the Lien securing such Indebtedness for so long as the Indebtedness is so secured, except that the foregoing restriction does not apply to:

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Limitation on Sale and Leaseback Transactions. We covenant in the indenture that we will not, and will not permit any Restricted Subsidiary to, enter into any Sale and Leaseback Transaction unless:

Definitions. Following are definitions of some of the terms used in the covenants described above.

“Attributable Debt” means, as to any lease under which any person is at the time liable for rent, at any date as of which the amount thereof is to be determined, the total net amount of rent required to be paid by such person under such lease during the remaining term, excluding amounts required to be paid on account of maintenance and repairs, services, insurance, taxes, assessments, water rates and similar charges and contingent rents, discounted from the respective due dates thereof at the rate of interest (or Yield to Maturity, in the case of original issue discount securities) borne by the then Outstanding Securities, compounded monthly.

“Capital Stock” means any and all shares, interests, rights to purchase, warrants, options, participations or other equivalents of or interests, however designated, in stock issued by a corporation.

“Consolidated Net Tangible Assets” means the aggregate amount of assets, less applicable reserves and other properly deductible items, after deducting:

all as set forth on our most recent consolidated balance sheet contained in our latest quarterly or annual report filed with the SEC under the Securities Exchange Act of 1934, as amended, and computed in accordance with generally accepted accounting principles.

“Funded Indebtedness” means, as applied to any person, all Indebtedness of such person maturing after, or renewable or extendible at the option of the person beyond, 12 months from the date of determination.

“Indebtedness” means obligations for money borrowed, evidenced by notes, bonds, debentures or other similar evidences of indebtedness.

“Lien” means any lien, mortgage, pledge, encumbrance, charge or security interest securing Indebtedness; provided, however, that the following types of transactions will not be considered, for purposes of this definition, to result in a Lien:

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“Non-Recourse Indebtedness” means, at any time, Indebtedness incurred after the date of the indenture by us or a Restricted Subsidiary in connection with the acquisition of property or assets by us or a Restricted Subsidiary or the financing of the construction of or improvements on property, whenever acquired, provided that, under the terms of this Indebtedness and under applicable law, the recourse at such time and thereafter of the lenders with respect to such Indebtedness is limited to the property or assets so acquired, or the construction or improvements, including Indebtedness as to which a performance or completion guarantee or similar undertaking was initially applicable to the Indebtedness or the related property or assets if the guarantee or similar undertaking has been satisfied and is no longer in effect. Indebtedness which is otherwise Non-Recourse Indebtedness will not lose its character as Non-Recourse Indebtedness because there is recourse to us, any Subsidiary of ours or any other person for (a) environmental or tax warranties and indemnities and such other representations, warranties, covenants and indemnities as are customarily required in such transactions or (b) indemnities for and liabilities arising from fraud, misrepresentation, misapplication or non-payment of rents, profits, insurance and condemnation proceeds and other sums actually received from secured assets to be paid to the lender, waste and mechanics’ liens or similar matters.

“Principal Property” means any natural gas distribution property located in the United States, except any property that in the opinion of our board of directors is not of material importance to the total business conducted by us and our consolidated Subsidiaries.

“Restricted Subsidiary” means any Subsidiary the amount of Consolidated Net Tangible Assets of which constitutes more than 10% of the aggregate amount of Consolidated Net Tangible Assets of us and our Subsidiaries.

“Sale and Leaseback Transaction” means any arrangement with any person in which we or any Restricted Subsidiary leases any Principal Property that has been or is to be sold or transferred by us or the Restricted Subsidiary to that person, other than any such arrangement involving:

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“Subsidiary” of ours means:

Consolidation, Merger or Sale of Assets. Under the terms of the indenture, we will be generally permitted to consolidate with or merge into another entity. We will also be permitted to sell or transfer our assets substantially as an entirety to another entity. However, we may not take any of these actions unless all of the following conditions are met:

In the event that we engage in one of these transactions and comply with the conditions listed above, we would be discharged from all our obligations and covenants under the indenture and all obligations under the Outstanding Securities, with the successor corporation or person succeeding to our obligations and covenants.

In the event that we engage in one of these transactions, the indenture provides that, if any Principal Property or Restricted Securities would thereupon become subject to any Lien securing Indebtedness, then the debt securities, other than debt securities not entitled to the benefits of specified covenants, must be secured, as to such Principal Property or Restricted Securities, equally and ratably with (or prior to or, in the case of debt securities that are subordinated in right of payment to the Indebtedness secured by such Lien or in the case of other Indebtedness of ours that is subordinated to the debt securities, on a subordinated basis to such Lien securing) the Indebtedness or obligations that upon the occurrence of such transaction would become secured by the Lien, unless the Lien could be created under the indenture without equally and ratably securing the debt securities (or, in the case of debt securities that are subordinated in right of payment to the Indebtedness secured by such Lien, on a subordinated basis to such Lien).

Modification or Waiver

There are two types of changes that we can make to the indenture and the debt securities.

Changes Requiring Approval. With the consent of the holders of at least a majority in principal amount of all outstanding debt securities of each series affected (including any such approvals obtained in connection with a tender or exchange offer for outstanding debt securities), we may make any changes, additions or deletions to any provisions of the indenture applicable to the affected series, or modify the rights of the holders of the debt securities of the affected series. However, without the consent of each holder affected, we cannot:

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Changes Not Requiring Approval. The second type of change does not require the consent of any holders of the debt securities. This type is limited to clarifications and certain other changes that would not adversely affect holders of the outstanding debt securities in any material respect. Additionally, we do not need any approval to make any change that affects only debt securities to be issued under the indenture after the changes take effect.

Further Details Concerning Voting. When taking a vote, we will use the following rules to decide how much principal amount to attribute to a debt security:

Debt securities will not be considered outstanding, and therefore not eligible to vote, if we have deposited or set aside in trust money for their payment or redemption. Debt securities will also not be eligible to vote if they have been fully defeased as described later under “Defeasance and Covenant Defeasance.”

Book-entry and other indirect holders should consult their banks or brokers for information on how approval may be granted or denied if we seek to change the indenture or the debt securities or request a waiver.

Events of Default

Holders of debt securities will have special rights if an Event of Default occurs as to the debt securities of their series that is not cured, as described later in this subsection. Please refer to the applicable prospectus supplement for information about any changes to the Events of Default, including any addition of a provision providing event risk or similar protection.

What is an Event of Default? The term “Event of Default” as to the debt securities of a series means any of the following:

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An Event of Default for a particular series of debt securities will not necessarily constitute an Event of Default for any other series of debt securities issued under the indenture.

The trustee may withhold notice to the holders of debt securities of a particular series of any default if it considers its withholding of notice to be in the interest of the holders of that series, except that the trustee may not withhold notice of a default in the payment of the principal of, any premium on, or the interest on the debt securities or in the payment of any sinking fund installment with respect to the debt securities.

Remedies if an Event of Default Occurs. If an event of default has occurred and is continuing, the trustee or the holders of at least 25 percent in principal amount of the debt securities of the affected series may declare the entire principal amount and all accrued interest of all the debt securities of that series to be due and immediately payable by notifying us, and the trustee, if the holders give notice, in writing. This is called a declaration of acceleration of maturity.

If the maturity of any series of debt securities is accelerated and a judgment for payment has not yet been obtained, the holders of a majority in principal amount of the debt securities of that series may cancel the acceleration if all events of default other than the non-payment of principal or interest on the debt securities of that series that have become due solely by a declaration of acceleration are cured or waived, and we deposit with the trustee a sufficient sum of money to pay:

Except in cases of default, where the trustee has some special duties, the trustee is not required to take any action under the indenture at the request of any holders unless the holders offer the trustee reasonable protection from expenses and liability. This is called an indemnity. If reasonable indemnity is provided, the holders of a majority in principal amount of the outstanding debt securities of the relevant series may direct the time, method and place of conducting any lawsuit or other formal legal action seeking any remedy available to the trustee. The trustee may refuse to follow those directions if the directions conflict with any law or the indenture or expose the trustee to personal liability. No delay or omission in exercising any right or remedy will be treated as a waiver of that right, remedy or Event of Default.

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Before a holder is allowed to bypass the trustee and bring his or her own lawsuit or other formal legal action or take other steps to enforce his or her rights or protect his or her interest relating to the debt securities, the following must occur:

However, a holder is entitled at any time to bring a lawsuit for the payment of money due on his or her debt securities on or after the due date without complying with the foregoing.

Holders of a majority in principal amount of the debt securities of the affected series may waive any past defaults other than the following:

Each year, we will furnish the trustee with a written statement of two of our officers certifying that, to their knowledge, we are in compliance with the indenture and the debt securities, or else specifying any default.

Book-entry and other indirect holders should consult their banks or brokers for information on how to give notice or direction to or make a request of the trustee and how to declare or cancel an acceleration.

Defeasance and Covenant Defeasance

Unless we provide otherwise in the applicable prospectus supplement, the provisions for full defeasance and covenant defeasance described below apply to each series of debt securities. In general, we expect these provisions to apply to each debt security that is not a floating rate or indexed debt security.

Full Defeasance. If there is a change in U.S. federal tax law, as described below, we can legally release ourselves from all payment and other obligations on the debt securities, called “full defeasance,” if we put in place the following arrangements for you to be repaid:

If we ever did accomplish defeasance, as described above, you would have to rely solely on the trust deposit for repayment of the debt securities. You could not look to us for repayment in the event of any shortfall. Conversely, the trust deposit would most likely be protected from claims of our lenders and other creditors if we

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ever become bankrupt or insolvent. If we accomplish a defeasance, we would retain only the obligations to register the transfer or exchange of the debt securities, to maintain an office or agency in respect of the debt securities and to hold moneys for payment in trust.

Covenant Defeasance. Under current federal tax law, we can make the same type of deposit described above and be released from any restrictive covenants in the indenture. This is called “covenant defeasance.” In that event, you would lose the protection of any such covenants but would gain the protection of having money and obligations issued or guaranteed by the U.S. government set aside in trust to repay the debt securities. In order to achieve covenant defeasance, we must do the following:

If we accomplish covenant defeasance, you can still look to us for repayment of the debt securities if there were a shortfall in the trust deposit or the trustee is prevented from making payment. In fact, if one of the remaining Events of Default occurred, such as our bankruptcy, and the debt securities became immediately due and payable, there may be a shortfall. Depending on the event causing the default, you may not be able to obtain payment of the shortfall.

Debt Securities Issued in Non-Global Form

If any debt securities cease to be issued in global form, they will be issued:

Holders may exchange their debt securities that are not in global form for debt securities of smaller denominations or combined into fewer debt securities of larger denominations, as long as the total principal amount is not changed.

Holders may exchange or transfer their debt securities at the office of the trustee. We may appoint the trustee to act as our agent for registering debt securities in the names of holders transferring debt securities, or we may appoint another entity to perform these functions or perform them ourselves.

Holders will not be required to pay a service charge to transfer or exchange their debt securities, but they may be required to pay for any tax or other governmental charge associated with the transfer or exchange. The transfer or exchange will be made only if our transfer agent is satisfied with the holder’s proof of legal ownership.

If we have designated additional transfer agents for a holder’s debt security, they will be named in the applicable prospectus supplement. We may appoint additional transfer agents or cancel the appointment of any particular transfer agent. We may also approve a change in the office through which any transfer agent acts.

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If any debt securities are redeemable and we redeem less than all those debt securities, we may stop the transfer or exchange of those debt securities during the period beginning 15 days before the day we mail the notice of redemption and ending on the day of that mailing, in order to freeze the list of holders to prepare the mailing. We may also refuse to register transfers or exchanges of any debt securities selected for redemption, except that we will continue to permit transfers and exchanges of the unredeemed portion of any debt security that will be partially redeemed.

If a debt security is issued as a global security, only the depository will be entitled to transfer and exchange the debt security as described in this section, since it will be the sole holder of the debt security.

Payment Mechanics

Who Receives Payment? If interest is due on a debt security on an interest payment date, we will pay the interest to the person or entity in whose name the debt security is registered at the close of business on the regular record date, discussed below, relating to the interest payment date. If interest is due at maturity but on a day that is not an interest payment date, we will pay the interest to the person or entity entitled to receive the principal of the debt security. If principal or another amount besides interest is due on a debt security at maturity, we will pay the amount to the holder of the debt security against surrender of the debt security at a proper place of payment, or, in the case of a global security, in accordance with the applicable policies of the depository.

Payments on Global Securities. We will make payments on a global security in accordance with the applicable policies of the depository as in effect from time to time. Under those policies, we will pay directly to the depository, or its nominee, and not to any indirect holders who own beneficial interests in the global security. An indirect holder’s right to those payments will be governed by the rules and practices of the depository and its participants, as described above under “What is a Global Security?”.

Payments on Non-Global Securities. For a debt security in non-global form, we will pay interest that is due on an interest payment date by check mailed on the interest payment date to the holder at his or her address shown on the trustee’s records as of the close of business on the regular record date. We will make all other payments by check, at the paying agent described below, against surrender of the debt security. We will make all payments by check in next-day funds; for example, funds that become available on the day after the check is cashed.

Alternatively, if a non-global security has a face amount of at least $1,000,000 and the holder asks us to do so, we will pay any amount that becomes due on the debt security by wire transfer of immediately available funds to an account at a bank in New York City on the due date. To request wire payment, the holder must give the paying agent appropriate transfer instructions at least five business days before the requested wire payment is due. In the case of any interest payment due on an interest payment date, the instructions must be given by the person who is the holder on the relevant regular record date. In the case of any other payment, we will make payment only after the debt security is surrendered to the paying agent. Any wire instructions, once properly given, will remain in effect unless and until new instructions are given in the manner described above.

Regular Record Dates. We will pay interest to the holders listed in the trustee’s records as the owners of the debt securities at the close of business on a particular day in advance of each interest payment date. We will pay interest to these holders if they are listed as the owner even if they no longer own the debt security on the interest payment date. That particular day, usually about two weeks in advance of the interest payment date, is called the “regular record date” and will be identified in the prospectus supplement.

Payment When Offices Are Closed. If any payment is due on a debt security on a day that is not a business day, we will make the payment on the next business day. Payments postponed to the next business day in this situation will be treated under the indenture as if they were made on the original due date. A postponement of this kind will not result in a default under any debt security or the indenture, and no interest will accrue on the postponed amount from the original due date to the next business day.

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Paying Agents. We may appoint one or more financial institutions to act as our paying agents, at whose designated offices debt securities in non-global form may be surrendered for payment at their maturity. We call each of those offices a paying agent. We may add, replace or terminate paying agents from time to time. We may also choose to act as our own paying agent. Initially, we have appointed the trustee, at its corporate trust office in New York City, as the paying agent. We must notify you of changes in the paying agents.

Book-entry and other indirect holders should consult their banks or brokers for information on how they will receive payments on their debt securities.

The Trustee Under the Indenture

U.S. Bank National Association is the trustee under the indenture for our debt securities. We will identify any other entity acting as the trustee for a series of debt securities that we may offer in the prospectus supplement for the offering of such debt securities.

The trustee may resign or be removed with respect to one or more series of debt securities and a successor trustee may be appointed to act with respect to these series.

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DESCRIPTION OF COMMON STOCK

General

Our authorized capital stock consists of 200,000,000 shares of common stock, no par value, of which 111,352,650 shares were outstanding on November 8, 2018. Each of our shares of common stock is entitled to one vote on all matters voted upon by shareholders. Our shareholders do not have cumulative voting rights. Our issued and outstanding shares of common stock are fully paid and nonassessable. There are no redemption or sinking fund provisions applicable to the shares of our common stock, and such shares are not entitled to any preemptive rights. Since we are incorporated in both Texas and Virginia, we must comply with the laws of both states when issuing shares of our common stock.

Holders of our shares of common stock are entitled to receive such dividends as may be declared from time to time by our board of directors from our assets legally available for the payment of dividends and, upon our liquidation, a pro rata share of all of our assets available for distribution to our shareholders.

American Stock Transfer & Trust Company is the registrar and transfer agent for our common stock.

Charter and Bylaws Provisions

Some provisions of our articles of incorporation and bylaws may be deemed to have an “anti-takeover” effect. The following description of these provisions is only a summary, and we refer you to our articles of incorporation and bylaws for more information. Our articles of incorporation and bylaws are included as exhibits to our annual reports on Form 10-K filed with the SEC. See “Where You Can Find More Information.”

Cumulative Voting. Our articles of incorporation prohibit cumulative voting. In general, in the absence of cumulative voting, one or more persons who hold a majority of our outstanding shares can elect all of the directors who are subject to election at any meeting of shareholders.

Removal of Directors. Our articles of incorporation and bylaws also provide that our directors may be removed only for cause and upon the affirmative vote of the holders of at least 75 percent of the shares then entitled to vote at an election of directors.

Fair Price Provisions. Article VII of our articles of incorporation provides certain “Fair Price Provisions” for our shareholders. Under Article VII, a merger, consolidation, sale of assets, share exchange, recapitalization or other similar transaction, between us or a company controlled by or under common control with us and any individual, corporation or other entity which owns or controls 10 percent or more of our voting capital stock, would be required to satisfy the condition that the aggregate consideration per share to be received in the transaction for each class of our voting capital stock be at least equal to the highest per share price, or equivalent price for any different classes or series of stock, paid by the 10 percent shareholder in acquiring any of its holdings of our stock. If a proposed transaction with a 10 percent shareholder does not meet this condition, then the transaction must be approved by the holders of at least 75 percent of the outstanding shares of voting capital stock held by our shareholders other than the 10 percent shareholder, unless a majority of the directors who were members of our board immediately prior to the time the 10 percent shareholder involved in the proposed transaction became a 10 percent shareholder have either:

The provisions of Article VII may not be amended, altered, changed, or repealed except by the affirmative vote of at least 75 percent of the votes entitled to be cast thereon at a meeting of our shareholders duly called for

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consideration of such amendment, alteration, change, or repeal. In addition, if there is a 10 percent shareholder, such action must also be approved by the affirmative vote of at least 75 percent of the outstanding shares of our voting capital stock held by the shareholders other than the 10 percent shareholder.

Shareholder Proposals and Director Nominations. Our shareholders can submit shareholder proposals and nominate candidates for the board of directors if the shareholders follow the advance notice procedures described in our bylaws.

Shareholder proposals (other than those sought to be included in our proxy statement) must be submitted to our corporate secretary at least 60 days, but not more than 85 days, before the annual meeting; provided, however, that if less than 75 days’ notice or prior public disclosure of the date of the annual meeting is given or made to shareholders, notice by the shareholder to be timely must be received by our corporate secretary no later than the close of business on the 25th day following the day on which such notice of the date of the annual meeting was provided or such public disclosure was made. The notice must include a description of the proposal, the shareholder’s name and address and the number of shares held, and all other information which would be required to be included in a proxy statement filed with the SEC if the shareholder were a participant in a solicitation subject to the SEC’s proxy rules. To be included in our proxy statement for an annual meeting, our corporate secretary must receive the proposal at least 120 days prior to the anniversary of the date we mailed the proxy statement for the prior year’s annual meeting.

To nominate directors, shareholders must submit a written notice to our corporate secretary at least 60 days, but not more than 85 days, before a scheduled meeting; provided, however, that if less than 75 days’ notice or prior public disclosure of the date of the annual meeting is given or made to shareholders, such nomination shall have been received by our corporate secretary no later than the close of business on the 25th day following the day on which such notice of the date of the annual meeting was mailed or such public disclosure was made. The notice must include the name and address of the shareholder and of the shareholder’s nominee, the number of shares held by the shareholder, a representation that the shareholder is a holder of record of common stock entitled to vote at the meeting, and that the shareholder intends to appear in person or by proxy to nominate the persons specified in the notice, a description of any arrangements between the shareholder and the shareholder’s nominee, information about the shareholder’s nominee required by the SEC and the written consent of the shareholder’s nominee to serve as a director.

Shareholder proposals and director nominations that are late or that do not include all required information may be rejected. This could prevent shareholders from bringing certain matters before an annual or special meeting or making nominations for directors.

PLAN OF DISTRIBUTION

We may sell the securities offered by this prospectus and a prospectus supplement as follows:

We, directly or through agents or dealers, may sell, and the underwriters may resell, the securities in one or more transactions, including:

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The securities may be sold at a fixed price or prices which may be changed, at market prices prevailing at the time of sale, at prices related to such prevailing market prices or at negotiated prices.

We may designate underwriters or agents to solicit purchases of shares of our common stock for the period of their appointment and to sell securities on a continuing basis, including pursuant to “at-the-market offerings.” We will do so pursuant to the terms of a distribution agreement between us and the underwriters or agents. If we engage in at-the-market sales pursuant to a distribution agreement, we will issue and sell the shares to or through one or more underwriters or agents, which may act on an agency basis or on a principal basis. During the term of any such distribution agreement, we may sell shares on a daily basis in exchange transactions or otherwise as we agree with the underwriters or agents. The distribution agreement may provide that any shares of our common stock sold will be sold at prices related to the then prevailing market prices for our securities. Therefore, exact figures regarding net proceeds to us or commissions to be paid are impossible to determine and will be described in a prospectus supplement. The terms of each such distribution agreement will be set forth in more detail in a prospectus supplement to this prospectus. To the extent that any named underwriter or agent acts as principal pursuant to the terms of a distribution agreement, or if we offer to sell shares of our common stock through another broker dealer acting as underwriter, then such named underwriter may engage in certain transactions that stabilize, maintain or otherwise affect the price of our shares. We will describe any such activities in the prospectus supplement relating to the transaction. To the extent that any named broker dealer or agent acts as agent on a best efforts basis pursuant to the terms of a distribution agreement, such broker dealer or agent will not engage in any such stabilization transactions.

Agents designated by us from time to time may solicit offers to purchase the securities. We will name any such agent involved in the offer or sale of the securities and set forth any commissions payable by us to such agent in a prospectus supplement relating to any such offer and sale of securities. Unless otherwise indicated in the prospectus supplement, any such agent will be acting on a best efforts basis for the period of its appointment. Any such agent may be deemed to be an underwriter of the securities, as that term is defined in the Securities Act.

If underwriters are used in the sale of securities, securities will be acquired by the underwriters for their own account and may be resold from time to time in one or more transactions. Securities may be offered to the public either through underwriting syndicates represented by one or more managing underwriters or directly by one or more firms acting as underwriters. If an underwriter or underwriters are used in the sale of securities, we will execute an underwriting agreement with such underwriter or underwriters at the time an agreement for such sale is reached. We will set forth in the prospectus supplement the names of the specific managing underwriter or underwriters, as well as any other underwriters, and the terms of the transactions, including compensation of the underwriters and dealers. Such compensation may be in the form of discounts, concessions or commissions. Underwriters and others participating in any offering of securities may engage in transactions that stabilize, maintain or otherwise affect the price of such securities. We will describe any such activities in the prospectus supplement.

We may elect to list any class or series of securities on any exchange, but we are not currently obligated to do so. It is possible that one or more underwriters, if any, may make a market in a class or series of securities, but the underwriters will not be obligated to do so and may discontinue any market making at any time without notice. We cannot give any assurance as to the liquidity of the trading market for any of the securities we may offer.

If a dealer is used in the sale of the securities, we or an underwriter will sell such securities to the dealer, as principal. The dealer may then resell such securities to the public at varying prices to be determined by such

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dealer at the time of resale. The prospectus supplement will set forth the name of the dealer and the terms of the transactions.

We may directly solicit offers to purchase the securities, and we may sell directly to institutional investors or others. These persons may be deemed to be underwriters within the meaning of the Securities Act with respect to any resale of the securities. The prospectus supplement will describe the terms of any such sales, including the terms of any bidding, auction or other process, if used.

Agents, underwriters and dealers may be entitled under agreements which may be entered into with us to indemnification by us against specified liabilities, including liabilities under the Securities Act, or to contribution by us to payments they may be required to make in respect of such liabilities. The prospectus supplement will describe the terms and conditions of such indemnification or contribution. Some of the agents, underwriters or dealers, or their affiliates, may engage in transactions with or perform services for us and our subsidiaries in the ordinary course of their business.

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LEGAL MATTERS

Gibson, Dunn & Crutcher LLP and Hunton Andrews Kurth LLP, Richmond, Virginia, have each rendered an opinion with respect to the validity of the securities that may be offered under this prospectus. We filed these opinions as exhibits to the registration statement of which this prospectus is a part. If counsel for any underwriters passes on legal matters in connection with an offering made under this prospectus, we will name that counsel in the prospectus supplement relating to that offering.

EXPERTS

The consolidated financial statements of Atmos Energy appearing in our Annual Report (Form 10-K) for the fiscal year ended September 30, 2018 (including the schedule appearing therein), and the effectiveness of Atmos Energy’s internal control over financial reporting as of September 30, 2018 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and current reports, proxy statements and other information with the Securities and Exchange Commission under the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

The SEC maintains a website that contains reports, proxy statements and other information about issuers, like us, who file electronically with the SEC. The address of that site is www.sec.gov. Unless specifically listed below under “Incorporation of Certain Documents by Reference” the information contained on the SEC website is not incorporated by reference into this prospectus.

You can also inspect reports, proxy statements and other information about us at the offices of the New York Stock Exchange, Inc., 11 Wall Street, New York, New York 10005.

We have filed with the SEC a registration statement on Form S-3, of which this prospectus is a part, which registers the securities we are offering. The registration statement, including the attached exhibits and schedules, contains additional relevant information about us and the securities offered. The rules and regulations of the SEC allow us to omit certain information included in the registration statement from this prospectus.

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INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” information in this prospectus that we have filed with it. This means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is considered to be part of this prospectus, except for any information that is superseded by information that is included directly in this prospectus or the applicable prospectus supplement relating to an offering of our securities.

We incorporate by reference into this prospectus the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the termination of our offering of securities. These additional documents include periodic reports, such as annual reports on Form 10-K and quarterly reports on Form 10-Q, and current reports on Form 8-K (other than information furnished under Items 2.02 and 7.01 or corresponding information furnished under Item 9.01 as an exhibit, which is deemed not to be incorporated by reference in this prospectus), as well as proxy statements (other than information identified in them as not incorporated by reference). You should review these filings as they may disclose a change in our business, prospects, financial condition or other affairs after the date of this prospectus.

This prospectus incorporates by reference the documents listed below that we have filed with the SEC but have not been included or delivered with this document:

These documents contain important information about us and our financial condition.

You may obtain a copy of any of these filings, or any of our future filings, from us without charge by requesting it in writing or by telephone at the following address or telephone number:

Atmos Energy Corporation

1800 Three Lincoln Centre

5430 LBJ Freeway

Dallas, Texas 75240

Attention: Jennifer Hills

(972) 934-9227

Our website is www.atmosenergy.com; any information on or connected to our website is not part of this prospectus.

25

$650,000,000

Atmos Energy Corporation

Common Stock

PROSPECTUS SUPPLEMENT

Goldman Sachs & Co. LLC

BofA Merrill Lynch

Wells Fargo Securities

November                 , 2018