Exhibit 4.3  Execution Version  SECOND AMENDING AGREEMENT  THIS AGREEMENTdated as of October 18, 2011.  AMONG:  NOVA CHEMICALS CORPORATION, a corporation subsisting under the laws of the Province of New Brunswick (hereinafter referred to as the Borrower),  OF THE FIRST PART  - and -  THE FINANCIAL INSTITUTIONS AND OTHER PERSONS NAMED ON THE SIGNATURE PAGES HERETO, as Lenders  OF THE SECOND PART  - and -  THE TORONTO-DOMINION BANK,a Canadian chartered bank, as administrative agent of the Lenders (hereinafter referred to as the Agent),  OF THE THIRD PART  WHEREASthe parties hereto are parties to the Credit Agreement;  AND WHEREASthe parties hereto have agreed to amend and supplement certain provisions of the Credit Agreement as set out herein;  NOW THEREFOREin consideration of the covenants and agreements herein contained and other good and valuable consideration, the receipt and sufficiency of which are hereby conclusively acknowledged by each of the parties hereto, the parties hereto covenant and agree as follows:  1.INTERPRETATION  1.1In this Agreement, the following terms shall have the meanings set forth below (unless something in the subject matter or context is inconsistent therewith):  Agreement means this second amending agreement, as amended, modified, supplemented or restated from time to time.


Credit Agreement means the Restated Credit Agreement made as of November 17, 2009 among NOVA Chemicals Corporation, as borrower, The Toronto-Dominion Bank, as administrative agent, and the financial institutions and other persons named on the signature pages thereto as lenders, as amended by the First Amending Agreement dated as of October 28, 2010 and as further amended, supplemented, modified or restated from time to time.  Effective Date means the first date on which all of the conditions precedent set forth in Section 3 hereof have been satisfied (or waived by the Majority Lenders).  1.2Capitalized terms used herein without express definition shall have the same meanings herein as are ascribed thereto in the Credit Agreement.  1.3The division of this Agreement into Sections and the insertion of headings are for convenience of reference only and shall not affect the construction or interpretation of this Agreement.  The terms this Agreement, hereof, hereunder and similar expressions refer to this Agreement and not to any particular Section or other portion hereof and include any agreements supplemental hereto.  1.4This Agreement shall be governed by and construed in accordance with the laws of the Province of Alberta and federal laws of Canada applicable therein.  1.5This Agreement shall be effective on the Effective Date.  2.AMENDMENTS  2.1The definition of Applicable Pricing Margin in Section 1.1 of the Credit Agreement is amended by deleting the pricing table therein and replacing same with the following new pricing table (and these pricing changes shall be applied to existing Outstandings in accordance with proviso (ii) in the definition of Applicable Pricing Margin):  Level

Senior Debt to   Cash Flow Ratio

BA Stamping Fee /   LIBOR Loan /   LC Fee   (in bps)

Prime Loans and   USBR Loans   (in bps)1

< 1.0

250

1502

>1.0 to < 2.0

275

1753

>2.0 to <3.0

325

225  2.2The definitions of Huntsman Preferred Stock and Huntsman Preferred Stock  Obligations in Section 1.1 of the Credit Agreement, including all cross references thereto, are deleted.  2.3The definition of Renewal Date in Section 1.1 of the Credit Agreement is amended by deleting November 17 and replacing same with December 17.  2


2.4The definition of Standby Fee Margin in Section 1.1 of the Credit Agreement is amended by deleting the pricing table therein and replacing same with the following new pricing table:  Level

Senior Debt to   Cash Flow Ratio

Standby Fee   (in bps)1

< 1.0

62.52

>1.0 to < 2.0

68.753

>2.0 to <3.0

81.25  2.5The definition of Utilization Fee in Section 1.1 of the Credit Agreement, including all cross references thereto and Section 3.7, are deleted.  2.6Section 2.3(a) of the Credit Agreement is amended in full to read as follows:  The Borrower may, at its option, by delivering to the Agent an Extension Request, request the Lenders to extend the Maturity Date for an additional period of one, two, three or four years; provided that (i) this request cannot be made more than 90 days or less than 60 days before each Renewal Date and (ii) the new Maturity Date cannot extend for more than four years from the applicable Renewal Date.  2.7Section 5.1(b) of the Credit Agreement is amended by deleting U.S.$75,000,000 and replacing same with U.S. $125,000,000.  2.8Section 8.1(f)(iii) of the Credit Agreement is amended by deleting three year and replacing same with four year.  2.9Section 12.1(a) of the Credit Agreement is amended by adding the following new sentence at the end thereof:  Notwithstanding anything herein to the contrary, (i) the Dodd-Frank Wall Street Reform and Consumer Protection Act and all regulations, requests, rules, guidelines or directives thereunder or issued in connection therewith and (ii) all requests, rules, guidelines or directives promulgated by the Bank for International Settlements, the Basel Committee on Banking Supervision (or any successor or similar authority) or the United States, Canadian or other regulatory authorities, in each case pursuant to Basel III ((i) and (ii) being, the New Rules), shall in each case be deemed to be a change in applicable Law for the purposes of this Section 12.1, regardless of the date enacted, adopted or issued.  2.10Each Lender acknowledges that the Maturity Date has been extended to December 17, 2015.  3


3.CONDITIONS PRECEDENT TO EFFECTIVENESS  This Agreement will become effective upon the following conditions being met (or waived in writing by the Majority Lenders) including the receipt by the Agent, for and on behalf of the Majority Lenders, of the following documents and payments each in full force and effect, and in form and substance satisfactory to the Agent, acting reasonably:  (a)a fully executed copy of this Agreement (including the Confirmation of Guarantees attached hereto); and  (b)all amendment fees payable by the Borrower to the Lenders in respect of the amendments provided for herein.  4.REPRESENTATIONS AND WARRANTIES  The Borrower represents and warrants to the Agent and the Lenders as follows on and as of the date hereof:  (a)Subsistence.The Borrower is validly subsisting under the laws of the Province of New Brunswick and has full corporate power and capacity to enter into and perform its obligations under this Agreement.  (b)Authorization and Status of Agreement.This Agreement has been duly authorized, executed and delivered by the Borrower and does not conflict with or contravene the constating documents or by-laws or any resolutions of the Borrower.  (c)Enforceability.This Agreement constitutes valid and binding obligations of the Borrower and is enforceable against it in accordance with its terms, except to the extent that enforceability may be limited by applicable bankruptcy, insolvency or similar laws affecting the enforcement of creditors rights generally and by general principles of equity.  (d)No Default.No Default or Event of Default has occurred and is continuing.  The representations and warranties set out in this Agreement shall survive the execution and delivery of this Agreement and the making of each Drawdown, notwithstanding any investigations or examinations which may be made by the Agent, the Lenders or Lenders Counsel.  Such representations and warranties shall survive until the Credit Agreement has been terminated.  5.CONFIRMATION OF CREDIT AGREEMENT  The Credit Agreement and all covenants, terms and provisions thereof, except as expressly amended and supplemented by this Agreement, shall be and continue to be in full force and effect. The Credit Agreement as amended and supplemented by this  4


Agreement is hereby ratified and confirmed and shall from and after the date hereof continue in full force and effect as herein amended and supplemented.  6.FURTHER ASSURANCES  The parties hereto shall from time to time do all such further acts and things and execute and deliver all such documents as are required in order to effect the full intent of and fully perform and carry out the terms of this Agreement.  7.COUNTERPARTS  This Agreement may be executed in any number of counterparts, including by facsimile, each of which shall be deemed to be an original and all of which taken together shall be deemed to constitute one and the same instrument, and it shall not be necessary in making proof of this Agreement to produce or account for more than one such counterpart.  5


IN WITNESS WHEREOFthe parties hereto have executed this Agreement.  BORROWER:NOVA   CHEMICALS CORPORATIONPer:
/s/   Randy WoelfelName:   Randy WoelfelTitle:   CEOPer:
/s/   Todd KarranName:   Todd KarranTitle:   CFOAGENT:THE   TORONTO-DOMINION BANK, as AgentPer:
/s/   Feroz HaqName:   Feroz HaqTitle:   Vice President, Loan Syndications - AgencyPer:Name:Title:LENDERS:THE   TORONTO-DOMINION BANKPer:
/s/   Greg HickawayName:   Greg HickawayTitle:   Managing DirectorPer:
/s/   Glen CameronName:   Glen CameronTitle:   Vice President


ROYAL   BANK OF CANADAPer:
/s/   Chris CowanName:   Chris CowanTitle:   Authorized SignatoryPer:Name:Title:HSBC   BANK CANADAPer:
/s/   Vivek VarmaName:   Vivek VarmaTitle:   DirectorPer:
/s/   Fabrizio CarranoName:   Fabrizio CarranoTitle:   VPBARCLAYS   BANK PLCPer:
/s/   Michael MozerName:   Michael MozerTitle:   Vice PresidentPer:Name:Title:EXPORT   DEVELOPMENT CANADAPer:
/s/   Richard LeongName:   Richard LeongTitle:   Asset ManagerPer:
/s/   Mathew DevineName:   Mathew DevineTitle:   Senior Asset Manager  2


THE   BANK OF NOVA SCOTIAPer:
/s/   John FrazellName:   John FrazellTitle:   DirectorPer:Name:Title:CANADIAN   WESTERN BANKPer:
/s/   Duncan LevyName:   Duncan LevyTitle:   Manager, Energy LendingPer:
/s/   : D.R. (Doug) CrookName:   D.R. (Doug) CrookTitle:   Senior AVP & Manager, Energy Lending  3


Confirmation of Guarantees  For good and valuable consideration (the receipt and sufficiency of which is hereby conclusively acknowledged) each of the undersigned in its capacity as a guarantor pursuant to its Restricted Subsidiary Guarantee hereby: (a) consents and agrees to the terms of the above Second Amending Agreement; (b) acknowledges and confirms the representations and warranties applicable to it in the above Second Amending Agreement; and (c) acknowledges that its Restricted Subsidiary Guarantee remains in full force and effect in all respects notwithstanding the amendments contained in the above Second Amending Agreement and shall continue to exist and apply to all Loan Indebtedness and Secured Swap Obligations including, without limitation, the Loan Indebtedness of the Borrower under the Credit Agreement as amended by the above Second Amending Agreement.  This Confirmation is in addition to and shall not limit, derogate from or otherwise affect the provisions of the Security, as amended prior to the date hereof.  Capitalized terms used herein shall have the same meanings herein as are ascribed thereto in the above Second Amending Agreement.  NOVA CHEMICALS (CANADA) LTD.

NOVA PETROCHEMICALS LTD.Per:
/s/   Todd Karran

Per:
/s/   Randy WoelfelName:
Todd   Karran

Name:
Randy   WoelfelTitle:
SVP &   CFO

Title:
SVP &   COOPer:
/s/   Alan Pretter

Per:
/s/   Todd KarranName:
Alan   Pretter

Name:
Todd   KarranTitle:
Asst.   Corp. Secretary

Title:
SVP &   CFONOVA CHEMICALS INC.

NOVA CHEMICALS (INTERNATIONAL) S.A.Per:
/s/   Randy Woelfel

Per:
/s/   Todd KarranName:
Randy   Woelfel

Name:
Todd   KarranTitle:
CEO

Title:
DirectorPer:
/s/   Todd KarranName:
Todd   KarranTitle:
SVP &   CFO