Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  þ    No  ¨

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  þ    No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer”, “smaller reporting company”, and "emerging growth company" in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act)    Yes  ¨    No  þ

Number of shares outstanding of each of the issuer’s classes of common stock, as of August 3, 2018.January 30, 2019.

Atmos Energy Corporation (“Atmos Energy” or the “Company”) isand its subsidiaries are engaged in the regulated natural gas distribution and pipeline and storage businesses. Our distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our regulated divisions and subsidiaries operate.

Our distribution business delivers natural gas through sales and transportation arrangements to over three million residential, commercial, public authority and industrial customers through our six regulated distribution divisions, which at June 30,December 31, 2018, covered service areas located in eight states.

Our pipeline and storage business, which is also subject to federal and state regulations, includes the transportation of natural gas to our Texas and Louisiana distribution systems and the management of our underground storage facilities used to support our distribution business in various states.

These consolidated interim-period financial statements have been prepared in accordance with accounting principles generally accepted in the United States on the same basis, aside from accounting policy changes noted below, as those used for the Company’s audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2017.2018. In the opinion of management, all material adjustments (consisting of normal recurring accruals) necessary for a fair presentation have been made to the unaudited consolidated interim-period financial statements. These consolidated interim-period financial statements are condensed as permitted by the instructions to Form 10-Q and should be read in conjunction with the audited consolidated financial statements of Atmos Energy Corporation included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2017.2018. Because of seasonal and other factors, the results of operations for the nine-monththree-month period ended June 30,December 31, 2018 are not indicative of our results of operations for the full 20182019 fiscal year, which ends September 30, 2018.2019.

No events have occurred subsequent to the balance sheet date that would require recognition or disclosure in the condensed consolidated financial statements.

Our accounting policies are described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2017.2018.

In May 2014, the Financial Accounting Standards Board (FASB) issued a comprehensive new revenue recognition standard that will supersedesuperseded virtually all existing revenue recognition guidance under generally accepted accounting principles in the United States. Under the new standard, an entity will recognizerecognizes revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies may need to use more judgment and make more estimates than under current guidance. The new guidance will become effective for us October 1, 2018 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption.

In January 2016, the FASB issued guidance related to the classification and measurement of financial instruments. The amendments modify the accounting and presentation for certain financial liabilities and equity investments not consolidated or reported using the equity method. The guidance is effective for us beginningEffective October 1, 2018; limited early adoption is permitted. The standard will require that2018, changes in the fair value of our available-for-sale equity securities formerly designated as available-for-sale are now recognized in other non-operating expense on our condensed consolidated statement of comprehensive income. Additionally, in accordance with the guidance, we reclassified a net $8.2 million unrealized gain related to these equity securities from accumulated other comprehensive income to retained earnings. The accounting for debt securities designated as available-for-sale did not change as a result of this new guidance. Accordingly, changes in the fair value of these securities will continue to be recorded inas a component of accumulated other comprehensive income.

In March 2017, the FASB issued new guidance related to the statement of comprehensive income presentation of the components of net income.periodic benefit cost for an entity’s sponsored defined benefit pension and other postretirement plans. The new guidance requires entities to disaggregate the current service cost component of the net benefit cost from the other components and present it with other current compensation costs for related employees in the statement of comprehensive income. The other components of net benefit cost will be appliedpresented outside of income from operations on the statement of comprehensive income. In addition, under the new guidance only the service cost component of net benefit cost is eligible for capitalization (e.g., as part of inventory or property, plant, and equipment). The Federal Energy Regulatory Commission

We adopted the new guidance beginning on October 1, 2018. We continue to present the balance sheet asservice cost component of net periodic benefit cost within operation and maintenance expense; however, other components of the beginningnet periodic benefit cost are now presented separately within other non-operating expense on our condensed consolidated statement of comprehensive income. The changes in presentation were implemented on a retrospective basis in accordance with the guidance. In lieu of determining how each component of the fiscal yearnet periodic benefit cost was actually reflected in the condensed statement of adoption. We do not anticipatecomprehensive income, we elected to utilize a practical expedient that permits the use of the amounts disclosed for each component of the net periodic benefit cost in our pension and post-retirement benefit plans footnote as the basis to retroactively apply this standard to all prior periods presented. The new standard willdid not have a material impact on our financial position, results of operations or cash flows.

In August 2018, the FASB issued new guidance aligning the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). We are currently still evaluatingelected to early adopt the new guidance on a prospective basis, beginning October 1, 2018. As a result of the new guidance, we will defer onto the balance sheet those up-front costs of cloud computing arrangements if they would have been capitalized in a similar on-premise software solution. The new standard did not have a material impact on our financial statement presentation and related disclosures.position, results of operations or cash flows.

In February 2016, the FASB issued a comprehensive new leasing standard that will require lessees to recognize a lease liability and a right-of-use asset for all leases, including operating leases, with a term greater than 12 months on its balance sheet. The new standard will be effective for us beginning on October 1, 2019; early adoption is permitted.2019. The new leasing standard requires modified retrospective transition, which requires application of the new guidance at the beginning of the earliest comparative period presented in the year of adoption. Additionally, inIn January 2018, the FASB issued amendments to the standard that provides a practical expedient forto allow entities to not evaluate existing or expired land easements that were not previously accounted for as leases under the current guidance. In July 2018, the FASB issued an amendment to the standard that providesa practical expedient providing an additional and optional transition method to adopt the standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. We are currently evaluating the effect of this standard and amendments on our financial position, results of operations, cash flows and cash flows.business processes.

In June 2016, the FASB issued new guidance which will require credit losses on most financial assets measured at amortized cost and certain other instruments to be measured using an expected credit loss model. Under this model, entities will estimate credit losses over the entire contractual term of the instrument from the date of initial recognition of that instrument. In contrast, current U.S. GAAP is based on an incurred loss model that delays recognition of credit losses until it is probable the loss has been incurred. The new guidance also introduces a new impairment recognition model for available-for-sale debt securities that will require credit losses for available-for-sale debt securities to be recorded through an allowance account. The new standard will be effective for us beginning on October 1, 2021; early adoption is permitted beginning on October 1, 2019.permitted. We are currently evaluating the potential impact of this new guidance on our financial position, results of operations and cash flows. 

In March 2017,August 2018, the FASB issued new guidance related tothat modifies the income statement presentation of the components of net periodic benefit costdisclosure requirements for an entity’s sponsoredemployers that sponsor defined benefit pension andor other postretirement plans. The new guidance requires entities to disaggregateremoves the currentdisclosure requirements for the amounts of gain/loss and prior service cost componentcost/credit amortization expected in the following year and the disclosure of the net benefit cost from the other components and present it with other current compensation costs for related employeeseffect of a one-percentage-point change in the statement of income.health care cost trend rate, among other changes. The guidance adds certain disclosures including the weighted average interest crediting rate for cash balance plans and a narrative description for the significant change in gains and losses as well as any other components of net benefit cost will be presented outside of income from operations onsignificant change in the statement of income. In addition, only the service cost component of net benefit cost is eligible for capitalization (e.g., as part of inventoryplan obligations or property, plant, and equipment). The Federal Energy Regulatory Commission (“FERC”), which regulates interstate transmission pipelines and also establishes, through its Uniform System of Accounts, accounting practices of rate-regulated entities, has issued guidance that states it will permit an election to either continue to capitalize non-service benefit costs or to cease capitalizing such costs for regulatory purposes.  Accounting guidelines by the FERC are typically also followed by state commissions.  As such, we plan to continue to capitalize all components of net periodic benefit cost for ratemaking purposes and will defer the non-service cost components as a regulatory asset for U.S. GAAP reporting purposes.assets. The new guidance will beis effective for us in the fiscal year beginning on October 1, 2018 and for interim periods within that year.  The standard requires retrospective application of the amendment related to the presentation of non-service cost components outside of income from operations in the statement of income and prospective application of the change in eligible costs for capitalization. We do not anticipate the new standard will have a material impact on our financial position, results of operations or cash flows.

Accounting principles generally accepted in the United States require cost-based, rate-regulated entities that meet certain criteria to reflect the authorized recovery of costs due to regulatory decisions in their financial statements. As a result, certain costs are permitted to be capitalized rather than expensed because they can be recovered through rates. We record certain costs

Significant regulatory assets and liabilities as of June 30,December 31, 2018 and September 30, 20172018 included the following:

Income statements and capital expenditures for the three and nine months ended June 30,December 31, 2018 and 2017 by segment are presented in the following tables:

We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Additionally, the weighted-average shares outstanding for diluted EPS includes the incremental effects of the forward sale agreements, discussed in Note 7, when the impact is dilutive. Basic and diluted earnings per share for the three and nine months ended June 30,December 31, 2018 and 2017 are calculated as follows:

The nature and terms of our debt instruments and credit facilities are described in detail in Note 5 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2017. There2018. Other than as described below, there were no material changes in the terms of our debt instruments during the ninethree months ended June 30,December 31, 2018.

Long-term debt at June 30,December 31, 2018 and September 30, 20172018 consisted of the following:

We utilize short-term debt to provide cost-effective, short-term financing until it can be replaced with a balance of long-term debt and equity financing that achieves the Company’s desired capital structure with an equity-to-total-capitalization ratio between 50% and 60%, inclusive of long-term and short-term debt. Our short-term borrowing requirements are affected primarilydriven by construction work in progress and the seasonal nature of the natural gas business. Changes in the price of natural gas and the amount of natural gas we need to supply our customers’ needs could significantly affect our borrowing requirements. Our short-term borrowings typically reach their highest levels in the winter months.

Currently, our short-term borrowing requirements are satisfied through a combination of a $1.5 billion commercial paper program and three committed revolving credit facilities with third-party lenders that provide approximately $1.5 billion of total working capital funding. The primary source of our funding is our commercial paper program, which is supported by a five-year unsecured $1.5 billion credit facility. On March 26, 2018, we executed one of our two one-year extension options which extended the maturity date from September 25, 2021 tofacility that expires on September 25, 2022. The facility bears interest at a base rate or at a LIBOR-based rate for the applicable interest period, plus a spread ranging from zero percent to 1.25 percent, based on the Company’s credit ratings. Additionally, the facility contains a $250 million accordion feature, which provides the opportunity to increase the loan, total committed availabilityloan to $1.75 billion. At June 30,December 31, 2018, and September 30, 2017, a total of $244.8 million and $447.7 million wasthere were no amounts outstanding under our commercial paper program. At September 30, 2018, a total of $575.8 million was outstanding.

Additionally, we have a $25 million 364-day unsecured facility which was renewed effective April 1, 2018 and expires March 31, 2019, and a $10 million 364-day unsecured revolving credit facility, which is used primarily to issue letters of credit. At June 30,December 31, 2018, there were no borrowings outstanding under

The availability of funds under these credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total-debt-to-total-capitalization of no greater than 70 percent. At June 30,December 31, 2018, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 42 percent. In addition, both the

On March 28, 2016,November 13, 2018, we filed a registration statement with the Securities and Exchange Commission (SEC) that originally permitted us to issue, from time to time, up to $2.5$3.0 billion in common stock and/or debt securities, which expires March 28, 2019.November 13, 2021. This registration statement replaced our previous registration statement that was effectively exhausted in October 2018. At June 30,December 31, 2018, approximately $650 million$1.8 billion of securities remained available for issuance under the shelf registration statement.

On November 14, 2017,19, 2018, we filed a prospectus supplement under the registration statement relating to an at-the-market (ATM) equity sales program under which we may issue and sell shares of our common stock up to an aggregate offering price of $500 million (including shares of common stock that may be sold pursuant to a forward sale agreement entered into concurrently with the ATM equity sales program), which expires March 28, 2019.November 13, 2021. During the ninethree months ended June 30,December 31, 2018, no shares of common stock were sold under the ATM equity sales program.

On November 30, 2017, we filed a prospectus supplement under the previous registration statement relating to an underwriting agreement to sell 4,558,404 shares of our common stock for $400 million. After expenses, net proceeds from the offering were $395.1 million.

We record deferred gains (losses) in AOCI related to available-for-sale debt securities and interest rate cash flow hedges and prior to the sale of Atmos Energy Marketing, LLC (AEM) on January 1, 2017, commodity contractagreement cash flow hedges. Deferred gains (losses) for our available-for-sale debt securities and commodity contract cash flow hedges are recognized in earnings upon settlement, while deferred gains (losses) related to our interest rate agreement cash flow hedges are recognized in earnings as they are amortized. The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income (loss):.