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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 10-Q

AXIALL CORPORATION
(Exact name of registrant as specified in its charter)

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 ý No o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate web site, if any, 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 ý No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, non-accelerated filer, or a smaller reporting company. See definition of "large accelerated filer," "accelerated filer" and "smaller reporting 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 o No ý

Indicate the number of shares outstanding of each of the issuer's classes of common stock, as of the latest practicable date.

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AXIALL CORPORATION
FORM 10-Q
QUARTERLY PERIOD ENDED SEPTEMBER 30, 2014MARCH 31, 2015
INDEX

Contents

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PART I. FINANCIAL INFORMATION.

Item 1. FINANCIAL STATEMENTS.

AXIALL CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETSCondensed Consolidated Balance Sheets

(Unaudited)

See accompanying notes to unaudited condensed consolidated financial statements.

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AXIALL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONSCondensed Consolidated Statements of Operations

(Unaudited)

See accompanying notes to unaudited condensed consolidated financial statements.

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AXIALL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOMECondensed Consolidated Statements of Comprehensive Loss

(Unaudited)

See accompanying notes to unaudited condensed consolidated financial statements.

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AXIALL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWSCondensed Consolidated Statements of Cash Flows

(Unaudited)

Significant non-cash transactions

On January 28, 2013, we acquired substantially all of the assets and liabilities of PPG Industries, Inc.'s ("PPG") business relating to the production of chlorine, caustic soda and related chemicals (the "Merged Business" or the "PPG Chemicals Business"), through a merger between a subsidiary of PPG and a subsidiary of the Company (the "Merger"). The purchase price for these transactions was approximately $2.8 billion and consisted of: (i) the issuance of approximately 35.2 million shares of our common stock valued at approximately $1.8 billion; (ii) the assumption of $967.0 million of debt; and (iii) the assumption of certain other liabilities including pension and other postretirement obligations. See Note 2 to the unaudited condensed consolidated financial statements.

See accompanying notes to unaudited condensed consolidated financial statements.

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AXIALL CORPORATION
NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTSNotes to Unaudited Condensed Consolidated Financial Statements

1. BASIS OF PRESENTATION

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. The accompanying unaudited condensed consolidated financial statements reflect all of the adjustments that, in the opinion of management, are necessary to present fairly the financial position, results of operations and cash flows for the interim periods reported. Such adjustments are of a normal, recurring nature.

Our financial condition as of, and our operating results for, the three and nine month periodsperiod ended September 30, 2014March 31, 2015 are not necessarily indicative of the financial condition and results that may be expected for the full year ending December 31, 20142015 or any other interim period. Certain prior period amounts have been reclassified to conform to the current period's presentation. These reclassifications are of a normal recurring nature and did not impact the Company's operating income (loss) or consolidated net income.loss.

The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes to audited consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 20132014 (the "2013"2014 Annual Report"). There has been no material change in the significant accounting policies followed by us during the three and nine month periodsperiod ended September 30, 2014March 31, 2015 from those disclosed in the 20132014 Annual Report. Unless the context otherwise requires, references to "Axiall," the "Company," "we," "our" or "us," means Axiall Corporation and its consolidated subsidiaries.

2. MERGER WITH THE PPG CHEMICALS BUSINESS

On January 28, 2013, we completed our acquisition of substantially all of the assets and liabilities of the Merged Business and completed the related financings (collectively, the "Transactions"). We manage the Merged Business as part of our chlorovinyls business, and have reported the results of operations of the Merged Business as part of our chlorovinyls segment since January 28, 2013.

The purchase price of the Merged Business of approximately $2.8 billion consisted of: (i) the issuance of approximately 35.2 million shares of our common stock valued at approximately $1.8 billion; (ii) assumed debt of approximately $967.0 million; and (iii) the assumption of other liabilities, including pension liabilities and other postretirement obligations.

Summary Pro Forma Information.    The following unaudited pro forma financial information reflects our consolidated results of operations as if the Transactions had taken place on January 1, 2012. The pro forma information includes primarily adjustments for depreciation based on the estimated fair value of the property, plant and equipment acquired in the Merger, amortization of acquired intangible assets and interest expense on the debt we incurred to finance the Transactions. The pro forma

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information is not necessarily indicative of the results of operations that we would have reported had the Transactions actually closed on January 1, 2012, nor is it necessarily indicative of future results.

Disclosure of revenues and earnings of the Merged Business since January 28, 2013 on a stand-alone basis is not practicable, as the Merged Business is not being operated as a stand-alone business.

3. 2. NEW ACCOUNTING PRONOUNCEMENTS

In June 2014,April 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU" or "Update") 2015-05—Intangibles—Goodwill and Other-Internal-Use Software (Subtopic 350-40). The amendments in this Update provide explicit guidance to companies about fees paid in cloud-based computing arrangements for various hosting services. Previous GAAP guidance did not include such explicit direction. Specifically, the Update stipulates that if a cloud-based computing arrangement includes a software license, the company should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud-based computing arrangement does not include a software license, the company should account for the arrangement as a service contract. The guidance does not change the accounting treatment for service contracts. However, all software licenses within the scope of this Update should be accounted for consistent with other licenses of intangible assets. The amendments in this Update are effective for annual periods, including interim periods, beginning after December 15, 2015, and early adoption is permitted. We are evaluating the amendments in this Update and have not yet determined the impact on our consolidated financial statements.

In April 2015, the FASB issued ASU 2015-03—Interest—Imputation of Interest (Subtopic 835-30). The amendments in this Update simplifies the presentation of debt issuance costs by requiring debt issuance costs related to a recognized debt liability to be presented on the balance sheet as a direct deduction from the carrying amount of the related debt liability, similar to the accounting treatment for debt discounts. Previous GAAP guidance was different from International Financial Reporting Standards

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("IFRS"), as issued by the International Accounting Standards Board, which requires transactions to be deducted from the carrying value of the financial liability and not recorded as a separate asset, and conflicted with other FASB standards, specifically FASB Concept Statement 6. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this Update. The amendments in this Update are effective for financial statements issued for fiscal years beginning after December 15, 2015, and early adoption is permitted. We are evaluating the amendments in this Update and have not yet determined the impact on our consolidated financial statements.

In February 2015, the FASB issued ASU 2015-02—Consolidation (Topic 810)—Amendments to the Consolidation Analysis to assist companies in evaluating whether certain legal entities should be consolidated. The ASU stipulates that all legal entities are subject to reevaluation under the revised consolidation model in the guidance. This Update reduces the number of consolidation models, simplifies the FASB Accounting Standards Codification and improves current GAAP by placing more emphasis on risk of loss when determining a controlling financial interest. A reporting organization may no longer have to consolidate a legal entity under certain circumstances based solely on its fee arrangement when certain criteria are met. This reduces the frequency of the application of related-party guidance when determining a controlling financial interest in a variable interest entity ("VIE"). The Update changes the consolidation conclusions for public and private companies in several industries that typically make use of limited partnerships or VIEs. The amendments in this Update are effective for annual periods, including interim periods, beginning after December 15, 2015. We are evaluating the amendments in this Update and have not yet determined the impact on our consolidated financial statements.

In June 2014, FASB issued ASU 2014-12—Compensation—Stock Compensation (Topic 718). Under this Update:Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period (a consensus of the FASB Emerging Issues Task Force), a performance target that affects vesting, and that could be achieved after the requisite service period, would be treated as a performance condition. GAAP did not address these issues. The Update states that a reporting entity should apply existing guidance in Topic 718 to account for awards with performance conditions that affect the vesting of such awards. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. Compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the periods for which the requisite service has already been rendered. If the performance target becomes probable of being achieved before the end of the requisite service period, the remaining unrecognized compensation cost should be recognized prospectively over the remaining requisite service period. The total amount of compensation cost recognized during and after the requisite service period should reflect the number of awards that are expected to vest and should be adjusted to reflect those awards that ultimately vest. The requisite service period ends when the employee can cease rendering service and still be eligible to vest in the award if the performance target is achieved. The stated vesting period (which includes the period in which the performance target could be achieved) may differ from the requisite service period. The amendments in this Update are effective for annual reporting periods beginning after December 15, 2015. Earlier adoption is permitted. We are evaluating the amendments in this Update and have not yet determined the impact on our condensed consolidated financial statements.

In May 2014, the FASB issued ASU 2014-09,2014-09—Revenue from Contracts with Customers. The Update outlines a single, comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance issued by the FASB, including industry specific guidance. The Update provides accounting guidance for all revenue arising from contracts with customers and affects all entities that enter into contracts with customers to provide goods and services. The guidance also provides a model for the measurement and recognition of gains and losses on the sale of certain nonfinancial assets, such as property and equipment, including

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real estate. The Update is effective for annual reporting periods, including interim reporting periods within those periods, beginning after December 15, 2016. The new standard must be adopted using either a full retrospective approach for all periods presented in the period of adoption or a modified retrospective approach. The modified retrospective approach requires that the new standard be applied

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to all new and existing contracts as of the date of adoption, with a cumulative catch-up adjustment recorded to the opening balance of retained earnings at the effective date for existing contracts that still require performance by the entity. Under the modified retrospective approach, amounts reported prior to the date of adoption will be presented under existing guidance. The Update also requires entities to disclose both quantitative and qualitative information to enable users of the financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. We have not yet determined the impact of adopting the standard on our condensed consolidated financial statements, nor have we determined whether we will utilize the full retrospective or modified retrospective approach.

In April 2014, the FASB issued ASU 2014-08—Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. The amendments in this Update change the requirements for reporting discontinued operations in Subtopics 205 (Presentation of Financial Statements) and 360 (Property, Plant, and Equipment). The Update changes the criteria for reporting discontinued operations and enhances the FASB's convergence with International Accounting Standards. The Update improves the definition of discontinued operations by limiting discontinued operations reporting specifically to the disposal of a component or a group of components of an entity that results in a strategic shift that has (or will have) a major effect on an entity's operations and financial results when certain criteria are met. The Update raises the threshold for disposals to qualify as discontinued operations and expands the disclosure requirements for discontinued operations and certain other disposals that do not qualify as discontinued operations. The amendments in this Update are effective for annual periods beginning on or after December 15, 2014, and interim periods within that year. We are evaluating the amendments in this Update and do not expect them to have a material impact on our condensed consolidated financial statements.

In July 2013, the FASB issued ASU 2013-11, Income Taxes (Topic 740):Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists. Prior to this Update, GAAP did not include explicit guidance on the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward existed. The Update provides that a liability related to an unrecognized tax benefit would be offset against a deferred tax asset for a net operating loss carryforward, a similar tax loss or a tax credit carryforward if such settlement is required or expected in the event the uncertain tax position is disallowed. In that case, the liability associated with the unrecognized tax benefit is presented in the financial statements as a reduction to the related deferred tax asset for a net operating loss carryforward, a similar tax loss or a tax credit carryforward. In situations in which a net operating loss carryforward, a similar tax loss or a tax credit carryforward is not available at the reporting date under the tax law of the jurisdiction or the tax law of the jurisdiction does not require, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit will be presented in the financial statements as a liability and will not be combined with deferred tax assets. The amendments in this Update do not require new recurring disclosures. The Update is effective for fiscal years beginning after December 15, 2013. In accordance with this Update, at September 30, 2014, the Company reclassified liabilities associated with certain unrecognized tax benefits as a reduction to a deferred tax assets for a net operating loss carryforward in the amount of $4.5 million.

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4. 3. INVENTORIES

As of September 30, 2014March 31, 2015 and December 31, 2013,2014, the major classes of inventories were as follows:

5. 4. PROPERTY, PLANT AND EQUIPMENT, NET

As of September 30, 2014March 31, 2015 and December 31, 2013,2014, property, plant and equipment consisted of the following:

6. 5. GOODWILL AND OTHER INTANGIBLE ASSETS AND RESTRUCTURING

Our intangible assets consist of goodwill, customer relationships, supply contracts, technology and trade names, and technology.names. Goodwill is the excess of the cost of an acquired entity over the fair value of tangible and intangible assets (including, but not limited to, customer lists, supply contracts, technology and trade names and technology)names) acquired and liabilities assumed under acquisition accounting for business combinations.

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Goodwill.    As of March 31, 2015, we have two segments that contain reporting units with goodwill and intangible assets: our chlorovinyls segment includes goodwill in its chlor-alkali and derivatives and compound reporting units and our building products segment includes goodwill primarily in its siding reporting units.

Goodwill.    During the nine month period ended September 30, 2014, the Company recorded an immaterial correction of an error related to the overstatement of certain assets and deferred tax liabilities recorded in connection with the acquisition accounting for the Merged Business that were outside of the measurement period. The Company recognized a $0.7 million decrease in the fair value of acquired net assets and a $0.7 million increase to goodwill on the consolidated balance sheet as of September 30, 2014. Management performed an evaluation under Staff Accounting Bulletin No. 108 and concluded the effect of the adjustment is immaterial to the current and prior periods' financial

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statements.unit. The following table provides the detail of the changes made to goodwill during the ninethree months ended September 30, 2014.March 31, 2015.

Indefinite-lived intangible assets.    OurAs of March 31, 2015 and December 31, 2014, our indefinite-lived intangible assets consisted of certain trade names with a carrying value of $5.9 million and $6.0 million, at September 30, 2014respectively, net of cumulative translation adjustment.

Definite-lived intangible assets.    As of March 31, 2015 and December 31, 20132014, we had definite-lived intangible assets related to: (i) customer relationships, supply contracts, technology and trade names in our chlorovinyls segment; and (ii) customer relationships and technology in our building products segment.

Valuation of Goodwill and Indefinite-Lived Intangible Assets:    The carrying values of our goodwill and indefinite-lived intangible assets are tested for impairment annually in the fourth quarter, using a measurement date of October 1. In addition, we evaluate the carrying value of these assets for impairment between annual impairment tests if an event occurs or circumstances change that would indicate the carrying amounts may be impaired. Such events and indicators may include, without limitation, significant declines in industries in which our products are used, significant changes in the estimated future cash flows of our reporting units, significant changes in capital market conditions and significant changes in our market capitalization. As of September 30, 2014 we do not believe there have been any events or circumstances that would require us to perform an interim impairment test in our reporting units that carry goodwill and indefinite-lived intangible assets. However, certain factors including but not limited to a sustained decline in our market capitalization below its book value or further deterioration in our industry or market conditions could lead us to determine, in a future period, that an impairment test would be required and result in an impairment charge, which could have a negative impact on our result of operations.

Impairment testing for goodwill is a two-step test performed at a reporting unit level. The first step of the impairment analysis involves comparing the fair value of the reporting unit to its book value, including goodwill. If the fair value of the reporting unit exceeds the book value, goodwill is not considered impaired. If the book value exceeds the fair value, the second step of the impairment analysis is performed, in which we measure the amount of impairment. Our goodwill evaluations utilized discounted cash flow analyses and market multiple analyses in estimating fair value. The weighting of the discounted cash flow and market approaches varies by each reporting unit based on factors specific to each reporting unit. Inherent in our fair value determinations are certain judgments and estimates relating to future cash flows, including our interpretation of current economic indicators and market conditions, overall economic conditions and our strategic operational plans with regard to our business units. In addition, to the extent significant changes occur in market conditions, overall economic conditions or our strategic operational plan, it is possible that goodwill not currently impaired, may become impaired in the future.

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Definite-lived intangible assets.    At September 30, 2014 and December 31, 2013, we had definite-lived intangible assets in our building products segment that related to customer relationships and technology. In the acquisition of the Merged Business, we acquired definite-lived intangible assets in our chlorovinyls segment. The values of these assets acquired are $1.1 billion for customer relationships, $42.6 million for supply contracts, $14.9 million for technology and $6.0 million for trade names. At September 30, 2014 and December 31, 2013, there were no definite-lived intangible assets in our aromatics segment. The following table provides the definite-lived intangible assets, by reportable segment, as of September 30, 2014March 31, 2015 and December 31, 2013.2014.

The weighted average estimated useful life remaining for customer relationships, supply contracts, technology and definite-lived trade names and technology is approximately 16 years, 18 years, 16 years and 15 years, and 16 years, respectively.respectively, as of March 31, 2015. Amortization expense for the definite-lived intangible assets was $16.8$16.6 million and $15.2$16.8 million for the three months ended September 30,March 31, 2015 and 2014, and 2013, respectively and $51.4 million and $45.0 million for the nine months ended September 30, 2014 and 2013, respectively. The estimated annual amortization expense for definite-lived intangible assets for the next five fiscal years is approximately $67.1$66.4 million per year.

Restructuring:    In September 2013, we initiated a restructuring plan in our building products segment consistingPage 11 of various cost saving initiatives, including the reduction of overhead and plant labor, and the consolidation of various plants, primarily in the window and door profiles reporting unit, to improve utilization and efficiencies. During the three and nine month periods ended September 30, 2014, we recorded $1.0 million and $3.9 million, respectively, in restructuring charges in our building products segment that are included in Transaction-related costs and other, net in the unaudited condensed consolidated statements of operations. We expect to complete these restructuring initiatives in 2015 with additional expected restructuring charges in 2014 and 2015 totaling a combined $2.4 million.

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7. 6. OTHER ASSETS, NET

As of September 30, 2014March 31, 2015 and December 31, 2013,2014, other assets, net of accumulated amortization, consisted of the following: