d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… ·...

57
Use these links to rapidly review the document Table of Contents Table of Contents Filed Pursuant to Rule 424(b)(7) File No. 333-210226 The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to the securities has become effective under the Securities Act of 1933, as amended. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities, and we are not soliciting an offer to buy these securities, in any jurisdiction where the offer or sale is not permitted. Subject to completion, dated September 19, 2016 Prospectus Supplement to Prospectus dated March 15, 2016 TRINSEO S.A. 10,669,567 Ordinary Shares The selling shareholder named in this prospectus supplement is offering 10,669,567 of our ordinary shares. We will not receive any proceeds from the sale of our ordinary shares by the selling shareholder. Our ordinary shares are listed on the New York Stock Exchange under the symbol "TSE." On September 19, 2016, the last sale price of our ordinary shares as reported on the New York Stock Exchange was $55.76 per ordinary share. Investing in our ordinary shares involves substantial risk. Please read "Risk Factors" beginning on page S-8 of this prospectus supplement and on page 3 of the accompanying base prospectus. Neither the Securities and Exchange Commission nor any other regulatory body has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense. The underwriter has agreed to purchase our ordinary shares from the selling shareholder at a price of $ per share, which will result in approximately $ of proceeds to the selling shareholder before expenses. The underwriter may offer the ordinary shares from time to time for sale in one or more transactions on the New York Stock Exchange, 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 it and subject to its right to reject any order in whole or in part. We have agreed to reimburse the underwriter for certain expenses in connection with this offering. See "Underwriting." The underwriter expects to deliver the shares against payment in New York, New York on or about , 2016. Morgan Stanley The date of this prospectus supplement is , 2016

Transcript of d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… ·...

Page 1: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

UsetheselinkstorapidlyreviewthedocumentTableofContents

TableofContents

Filed Pursuant to Rule 424(b)(7) File No. 333-210226

The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to the securities hasbecome effective under the Securities Act of 1933, as amended. This preliminary prospectus supplement and the accompanying prospectus are not anoffer to sell these securities, and we are not soliciting an offer to buy these securities, in any jurisdiction where the offer or sale is not permitted.

Subject to completion, dated September 19, 2016

Prospectus Supplement to Prospectus dated March 15, 2016

TRINSEO S.A.10,669,567 Ordinary Shares

Thesellingshareholdernamedinthisprospectussupplementisoffering10,669,567ofourordinaryshares.Wewillnotreceiveanyproceedsfromthesaleofourordinarysharesbythesellingshareholder.

OurordinarysharesarelistedontheNewYorkStockExchangeunderthesymbol"TSE."OnSeptember19,2016,thelastsalepriceofourordinarysharesasreportedontheNewYorkStockExchangewas$55.76perordinaryshare.

Investing in our ordinary shares involves substantial risk. Please read "Risk Factors" beginning on page S-8 of thisprospectus supplement and on page 3 of the accompanying base prospectus.

NeithertheSecuritiesandExchangeCommissionnoranyotherregulatorybodyhasapprovedordisapprovedofthesesecuritiesorpassedupontheaccuracyoradequacyofthisprospectussupplementortheaccompanyingprospectus.Anyrepresentationtothecontraryisacriminaloffense.

Theunderwriterhasagreedtopurchaseourordinarysharesfromthesellingshareholderatapriceof$pershare,whichwillresultinapproximately$ofproceedstothesellingshareholderbeforeexpenses.TheunderwritermayoffertheordinarysharesfromtimetotimeforsaleinoneormoretransactionsontheNewYorkStockExchange,intheover-the-countermarket,throughnegotiatedtransactionsorotherwiseatmarketpricesprevailingatthetimeofsale,atpricesrelatedtoprevailingmarketpricesoratnegotiatedprices,subjecttoreceiptandacceptancebyitandsubjecttoitsrighttorejectanyorderinwholeorinpart.Wehaveagreedtoreimbursetheunderwriterforcertainexpensesinconnectionwiththisoffering.See"Underwriting."

TheunderwriterexpectstodeliverthesharesagainstpaymentinNewYork,NewYorkonorabout,2016.

Morgan Stanley

Thedateofthisprospectussupplementis,2016

Page 2: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Table of Contents

Prospectus

Wehavenotauthorizedanyonetoprovideanyinformationortomakeanyrepresentationsotherthanthosecontainedinorincorporatedbyreferenceintothisprospectussupplement,theaccompanyingprospectusorinanyfreewritingprospectuseswehaveprepared.Wetakenoresponsibilityfor,andcanprovidenoassuranceastothereliabilityof,anyotherinformationthatothersmaygiveyou.Thisprospectussupplementandtheaccompanyingprospectusareanoffertosellonlythesharesofferedhereby,butonlyundercircumstancesandinjurisdictionswhereitislawfultodoso.Theinformationcontainedinthisprospectussupplementandtheaccompanyingprospectusiscurrentonlyasofthedateoftheapplicabledocument.

S-i

ABOUTTHISPROSPECTUSSUPPLEMENT S-iiNON-GAAPFINANCIALMEASURES S-iiPROSPECTUSSUPPLEMENTSUMMARY S-1RISKFACTORS S-8CAUTIONARYNOTEREGARDINGFORWARD-LOOKINGSTATEMENTS S-11USEOFPROCEEDS S-13MARKETPRICEOFOURORDINARYSHARES S-14DIVIDENDPOLICY S-15DESCRIPTIONOFSHARECAPITAL S-16MATERIALUNITEDSTATESFEDERALINCOMEANDLUXEMBOURGTAXCONSIDERATIONS S-24SELLINGSHAREHOLDER S-34UNDERWRITING S-35LEGALMATTERS S-40EXPERTS S-40WHEREYOUCANFINDMOREINFORMATION S-40INCORPORATIONOFCERTAININFORMATIONBYREFERENCE S-40

AboutThisProspectus 1AboutTrinseoS.A. 2RiskFactors 3CautionaryNoteRegardingForward-LookingStatements 4UseofProceeds 6SellingShareholder 6PlanofDistribution 7LegalMatters 9Experts 9WhereYouCanFindMoreInformation 9IncorporationofCertainInformationbyReference 9

Page 3: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

ABOUT THIS PROSPECTUS SUPPLEMENT

Unlessotherwiseindicatedorthecontextotherwiserequires,theterms"Trinseo,""we,""us,""our,""ourCompany,"and"ourbusiness"refertoTrinseoS.A.togetherwithitsconsolidatedsubsidiaries.Priortoourformation,ourbusinesseswerewholly-ownedbyTheDowChemicalCompany,whichwerefertoas"Dow."Werefertoourpredecessorbusinessesas"theStyronbusiness."OnJune17,2010,investmentfundsadvisedormanagedbyBainCapitalPrivateEquity,LPacquiredtheStyronbusiness,andDowEuropeHoldingB.V.retainedanownershipinterestintheStyronbusinessthroughanindirectownershipinterestinus.Referencesto"sellingshareholder"and"Parent"refertoBainCapitalEverestManagerHoldingSCA,whoissellingsharespursuanttothisprospectussupplement.

Thisdocumentisintwoparts.Thefirstpartisthisprospectussupplement,whichdescribesthespecifictermsofthisofferingofordinarysharesandcertainothermattersrelatingtous,ourbusinessandprospects.Thesecondpart,theaccompanyingprospectus,containscertainotherinformation.

Theinformationcontainedinthisprospectussupplementmayadd,updateorchangeinformationcontainedintheaccompanyingprospectusorindocumentsthatwefileorhavefiledwiththeSecuritiesandExchangeCommission(the"SEC").Totheextenttheinformationcontainedinthisprospectussupplementdiffersorvariesfromtheinformationcontainedintheaccompanyingprospectusordocumentsincorporatedbyreferencefiledbeforethedateofthisprospectussupplement,theinformationinthisprospectussupplementwillsupersedesuchinformation.

NON-GAAP FINANCIAL MEASURES

WerefertothetermsEBITDA,AdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluationinthisprospectussupplement,theaccompanyingprospectusanddocumentsincorporatedbyreferencehereinandtherein.ThesearesupplementalfinancialmeasuresthatarenotpreparedinaccordancewithU.S.GenerallyAcceptedAccountingPrinciples("GAAP").Anyanalysisofnon-GAAPfinancialmeasuresshouldbeusedonlyinconjunctionwithresultspresentedinaccordancewithGAAP.

Seenote4tothesectiontitled"ProspectusSupplementSummary—SummaryHistoricalFinancialandOperatingData"foradescriptionofthecalculationofEBITDA,AdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluation,includingthereasonsthatwebelievethisinformationisusefultomanagementandwhyitmaybeusefultoinvestors,andareconciliationofEBITDA,AdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluationtothemostcloselycomparablefinancialmeasurecalculatedinaccordancewithGAAP.OurmeasurementsofEBITDA,AdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluationmaynotbecomparabletothoseofothercompanies.

S-ii

Page 4: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights information appearing elsewhere or incorporated by reference in this prospectus supplement and the accompanyingprospectus. This summary is not complete and does not contain all of the information that you should consider before investing in our ordinary shares. Youshould carefully read this entire prospectus supplement, the accompanying prospectus and the financial data and related notes and other informationincorporated by reference in this prospectus supplement and the accompanying prospectus before deciding whether to invest in our ordinary shares.

Our Company

Wearealeadingglobalmaterialscompanyengagedinthemanufactureandmarketingofsyntheticrubber,latex,andplastics,includingvariousspecialtyandtechnologicallydifferentiatedproducts.Webelievethatgrowthinoverallconsumerspendingandconstructionactivity,increaseddemandintheautomotiveindustryforhigherfuelefficiencyandlighter-weightmaterials,andimprovinglivingstandardsinemergingmarketswillresultingrowthintheglobalmarketsinwhichwecompete.Inaddition,webelieveourincreasingbusinesspresenceindevelopingregionssuchasChina,SoutheastAsia,andEasternEuropefurtherenhancesourprospects.

Wedevelopsyntheticrubber,latexandplasticsproductsthatareincorporatedintoawiderangeofourcustomers'productsthroughouttheworld,includingtiresandotherproductsforautomotiveapplications,carpetandartificialturfbacking,coatedpaperandpackagingboard,foodpackaging,appliances,medicaldevices,consumerelectronicsandconstructionapplications,amongothers.Weseektoregularlydevelopnewandimprovedproductsandprocesses,supportedbyourintellectualpropertyportfolio,designedtoenhanceourcustomers'productofferings.Wehavelong-standingrelationshipswithadiversebaseofglobalcustomers,manyofwhomareleadersintheirmarketsandrelyonusforformulation,technologicaldifferentiation,andcompoundingexpertisetofindsustainablesolutionsfortheirbusinesses.Manyofourproductsrepresentonlyasmallportionofafinishedproduct'sproductioncosts,butprovidecriticalfunctionalitytothefinishedproductandareoftenspecificallydevelopedtocustomerspecifications.Webelievetheseproducttraitsresultinsubstantialcustomerloyaltyforourproducts.

Wehavesignificantmanufacturingandproductionoperationsaroundtheworld,whichallowsustoserveourglobalcustomerbase.AsofDecember31,2015,ourproductionfacilitiesincluded34manufacturingplants(whichincludedatotalof80productionunits)at26sitesacross14countries,includingjointventuresandcontractmanufacturers.OurmanufacturinglocationsincludesitesinemergingmarketssuchasChinaandIndonesia.Additionally,asofDecember31,2015,weoperated11researchanddevelopment("R&D")facilitiesglobally,includingminiplants,developmentcentersandpilotcoaters,whichwebelievearecriticaltoourglobalpresenceandinnovationcapabilities.

Weareaglobalbusinesswithadiversegeographicrevenuemixandsignificantoperationsaroundtheworld.

S-1

Page 5: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

ForthesixmonthsendedJune30,2016,wegeneratednetsalesof$1,863.8million,netincomeof$172.6million,AdjustedEBITDAof$325.6millionandAdjustedEBITDAexcludinginventoryrevaluationof$322.4million.FortheyearendedDecember31,2015,wegeneratednetsalesof$3,971.9million,netincomeof$133.6million,AdjustedEBITDAof$492.0millionandAdjustedEBITDAexcludinginventoryrevaluationof$550.3million.AdditionalinformationregardingAdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluation,includingareconciliationofthesemetricstonetincome(loss),isincludedinnote4tothetable"—SummaryHistoricalFinancialandOperatingData."

Recent Developments

Share Repurchases

Duringthethirdquarterof2016,theCompanycompleteditsrepurchaseprogramannouncedonJune22,2016.Undertheprogram,theCompanypurchased1,759,194ordinarysharesfromitsshareholdersthroughacombinationofopenmarkettransactionsforanaggregatepurchaseamountofapproximately$100.0million.Theshareswererepurchasedataweighted-averagepricepershareof$56.68.

Corporate Information

Ourglobaloperatingcenterislocatedat1000ChesterbrookBoulevard,Suite300,Berwyn,Pennsylvania19312,andourtelephonenumberatthisaddressis(610)240-3200.Wemaintainawebsiteatwww.trinseo.com.Theinformationon,orthatcanbeaccessedthrough,ourwebsiteisnotpartofthisprospectussupplementortheaccompanyingprospectus,andyoushouldnotrelyonanysuchinformationinmakingthedecisionwhethertopurchaseourordinaryshares.

S-2

Page 6: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

The Offering

S-3

Ordinarysharesofferedbythesellingshareholder

10,669,567ordinaryshares.

Ordinarysharesoutstandingafterthisoffering

45,145,431ordinaryshares,excludingtreasuryshares.

Useofproceeds

Wewillnotreceiveanyoftheproceedsfromthesaleofourordinarysharesbythesellingshareholder.

Dividendpolicy

OnJuly20,2016,wemadearepaymentofequityof$0.30perordinarysharetoourshareholdersofrecordasofthecloseofbusinessonJuly6,2016.Althoughweexpecttocontinuetomakequarterlycashdistributionstoourshareholdersasrepaymentsofequityordividends,anyfuturedeterminationtopaydividendsormakeotherdistributionstoourshareholderswillbeatthediscretionofourboardofdirectors.See"DividendPolicy."

RiskfactorsYoushouldreadcarefullytheinformationsetforthunder"RiskFactors"hereinandintheaccompanyingprospectusforadiscussionoffactorsthatyoushouldconsiderbeforedecidingtoinvestinourordinaryshares.

NewYorkStockExchangetradingsymbol

"TSE".

Page 7: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Summary Historical Financial and Operating Data

Thefollowingtablesetsforthoursummaryhistoricalfinancialandoperatingdataandotherinformationasofthedatesandfortheperiodsindicated.ThehistoricalresultsofoperationsforthethreeandsixmonthperiodsendedJune30,2016and2015,andthehistoricalbalancesheetdataasofJune30,2016presentedbelowwerederivedfromourunauditedcondensedconsolidatedfinancialstatementsandtherelatednotestheretoincorporatedbyreferenceintothisprospectussupplement.ThehistoricalresultsofoperationsdatafortheyearsendedDecember31,2015,2014,and2013,andthehistoricalbalancesheetdataasofDecember31,2015and2014presentedbelowwerederivedfromourauditedconsolidatedfinancialstatementsandtherelatednotestheretoincorporatedbyreferenceintothisprospectussupplement.ThehistoricalbalancesheetdataasofJune30,2015wasderivedfromourunauditedcondensedconsolidatedfinancialstatementsandtherelatednotestheretonotincorporatedbyreferenceintothisprospectussupplement.ThehistoricalbalancesheetdataasofDecember31,2013wasderivedfromourauditedconsolidatedfinancialstatementsandtherelatednotestheretonotincorporatedbyreferenceintothisprospectussupplement.ThedatainthefollowingtablerelatedtoEBITDA,AdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluationareunauditedforallperiodspresented.

Ourhistoricalresultsarenotnecessarilyindicativeoftheresultstobeexpectedforanyfutureperiods.

Thissummaryhistoricalfinancialandotherdatashouldbereadinconjunctionwiththedisclosuressetforthunder"Management'sDiscussionandAnalysisofFinancialConditionandResultsofOperations"andtheconsolidatedfinancialstatementsandtherelatednotesthereto,bothofwhichcanbefoundinourQuarterlyReportonForm10-QforthequarterendedJune30,2016andinourAnnualReportonForm10-KfortheyearendedDecember31,2015,eachofwhichisincorporatedbyreferenceherein.

S-4

Page 8: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

S-5

Three Months Ended

June 30, Six Months Ended

June 30, Year Ended December 31,

(in millions, except per share data) 2016 2015 2016 2015 2015 2014 2013 Statement of Operations Data: Netsales(1) $ 969.7 $ 1,028.7 $ 1,863.8 $ 2,046.9 $ 3,971.9 $ 5,128.0 $ 5,307.4Costofsales(1) 800.0 886.5 1,554.4 1,801.7 3,502.8 4,830.6 4,949.4Grossprofit 169.7 142.2 309.4 245.2 469.1 297.4 358.0Selling,generalandadministrativeexpenses 52.2 50.7 106.7 102.4 208.0 232.6 216.9Equityinearningsofunconsolidatedaffiliates 38.6 40.8 73.6 77.5 140.2 47.7 39.1

Operating income 156.1 132.3 276.3 220.3 401.3 112.5 180.2Interestexpense,net 18.8 25.6 37.7 54.5 93.2 124.9 132.0Lossonextinguishmentoflong-termdebt(2) — 95.2 — 95.2 95.2 7.4 20.7Otherexpense,net 12.9 3.2 15.5 6.7 9.1 27.8 27.9Income (loss) before income taxes 124.4 8.3 223.1 63.9 203.8 (47.6) (0.4)Provisionforincometaxes 28.6 7.5 50.5 25.4 70.2 19.7 21.8Net income (loss) $ 95.8 $ 0.8 $ 172.6 $ 38.5 $ 133.6 $ (67.3) $ (22.2)Weightedaverageshares—basic 47.0 48.8 47.8 48.8 48.8 43.5 37.3Netincome(loss)pershare—basic $ 2.04 $ 0.02 $ 3.61 $ 0.79 $ 2.74 $ (1.55) $ (0.60)Weightedaverageshares—diluted 47.9 48.9 48.6 48.9 49.0 43.5 37.3Netincome(loss)pershare—diluted $ 2.00 $ 0.02 $ 3.55 $ 0.79 $ 2.73 $ (1.55) $ (0.60)Repaymentofequitypershare $ 0.30 — $ 0.30 — — — —Other Financial Data: Depreciationandamortization $ 24.9 $ 21.7 $ 47.9 $ 44.2 $ 96.8 $ 103.7 $ 95.2Capitalexpenditures,netofsubsidy(3) 26.7 13.7 53.2 41.4 107.1 98.6 54.8EBITDA(4) 168.1 55.6 308.7 162.6 393.8 181.0 226.8AdjustedEBITDA(4) 182.4 151.3 325.6 260.1 492.0 261.6 277.9AdjustedEBITDAexcludinginventoryrevaluation(4) 169.5 121.9 322.4 272.9 550.3 326.0 318.3

Balance Sheet Data: Cashandcashequivalents $ 465.2 $ 231.1 $ 431.3 $ 220.8 $ 196.5Workingcapital(5) 928.8 741.1 839.8 748.7 810.2Totalassets(6) 2,362.6 2,289.1 2,258.9 2,356.1 2,574.8Debt(6) 1,188.3 1,221.2 1,182.1 1,202.2 1,336.4Totalliabilities(6) 1,899.2 2,001.2 1,869.9 2,035.3 2,231.6Totalshareholders'equity 463.4 287.9 389.0 320.9 343.2

(1) Netsalesandcostofsalesincreaseordecreasebasedonfluctuationsinrawmaterialprices.Consistentwithindustrypractice,andaspermittedunderagreementswithmanyofourcustomers,rawmaterialpricechangesaregenerallypassedthroughtocustomersbymeansofcorrespondingpricechanges.

(2) ForthethreeandsixmonthsendedJune30,2015andtheyearendedDecember31,2015,thelossonextinguishmentofdebtof$95.2millionrelatedtotheCompany'sdebtrefinancinginMay2015,andwascomprisedofbothacallpremiumandthewrite-offofunamortizeddeferredfinancingfees.FortheyearendedDecember31,2014,thelossonextinguishmentofdebtrelatedtotheJuly2014redemptionof$132.5millioninaggregateprincipalamountofthe2019SeniorNotes,usingaportionoftheproceedsfromourinitialpublicoffering.FortheyearendedDecember31,2013,thelossonextinguishmentofdebtrelatedtotheJanuary2013amendmentofour2018SeniorSecuredCreditFacilityandtherepaymentof$1,239.0millionofoutstandingTermLoans.NosuchchargeswererecordedforthethreeandsixmonthsendedJune30,2016.

(3) Representscapitalexpenditures,netofgovernmentsubsidiesreceivedforsolutionstyrene-butadienerubber,orSSBR,expansionof$2.2millionand$18.8millionfortheyearsendedDecember31,2015and2013,respectively.The$2.2millionofgovernmentsubsidiesreceivedin2015werereceivedduringthethreeandsixmonthsendedJune30,2015.NogovernmentsubsidieswerereceivedinthethreeandsixmonthsendedJune30,2016orintheyearendedDecember31,2014.FortheyearendedDecember31,2014,capitalexpendituresincludeapproximately$26.1millionforthereacquisitionofproductioncapacityrightsattheCompany'srubberproductionfacilityinSchkopau,Germany.

(4) WebelievethatthepresentationofAdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluationprovidesinvestorswithausefulanalyticalindicatorofourperformanceandofourabilitytoserviceourindebtedness.

Page 9: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

S-6

WedefineAdjustedEBITDAasincome(loss)fromcontinuingoperationsbeforeinterestexpense,net;incometaxprovision;depreciationandamortizationexpense;lossonextinguishmentoflong-termdebt;assetimpairmentcharges;advisoryfeespaidtoaffiliatesofourParent;gainsorlossesonthedispositionsofbusinessesandassets;restructuringandotheritems.Wedescribetheseothercostsinmoredetailbelow.

WepresentAdjustedEBITDAexcludinginventoryrevaluationinordertofacilitatethecomparabilityofresultsbyinvestorsfromperiodtoperiodbyadjustingcostofsalestoreflectthecostofrawmaterialduringtheperiod,whichisoftenreferredtoasthereplacementcostmethodofinventoryvaluation.Webelievethismeasureminimizestheimpactofrawmaterialpurchasepricevolatilityinevaluatingourperformance.OurapproachtocalculatinginventoryrevaluationisintendedtorepresentthedifferencebetweentheresultsundertheFIFOandthereplacementcostmethods.However,ourcalculationcoulddifferfromthereplacementcostmethodifthemonthlyrawmaterialstandardsaredifferentfromtheactualrawmaterialpricesduringthemonthandproductionandpurchasevolumesdifferfromsalesvolumesduringthemonth.Thesefactorscouldhaveasignificantimpactontheinventoryrevaluationcalculation.

TherearelimitationstousingfinancialmeasuressuchasAdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluation.TheseperformancemeasuresarenotintendedtorepresentcashflowfromoperationsasdefinedbyGAAPandshouldnotbeusedasalternativestonetincome(loss)asindicatorsofoperatingperformanceortocashflowasmeasuresofliquidity.OthercompaniesinourindustrymaydefineAdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluationdifferentlythanwedo.Asaresult,itmaybedifficulttousetheseorsimilarly-namedfinancialmeasuresthatothercompaniesmayuse,tocomparetheperformanceofthosecompaniestoourperformance.Wecompensatefortheselimitationsbyprovidingreconciliationsoftheseperformancemeasurestoournetincome(loss),whichisdeterminedinaccordancewithGAAP.

AdjustedEBITDAandAdjustedEBITDAexcludinginventoryrevaluationarecalculatedasfollowsforthethreeandsixmonthsendedJune30,2016and2015andfortheyearsendedDecember31,2015,2014,and2013,respectively:

Three Months Ended

June 30,

Six Months Ended

June 30,

Year Ended

December 31, (in millions) 2016 2015 2016 2015 2015 2014 2013 Net income (loss) $ 95.8 $ 0.8 $ 172.6 $ 38.5 $ 133.6 $ (67.3) $ (22.2)Interestexpense,net 18.8 25.6 37.7 54.5 93.2 124.9 132.0Provisionforincometaxes 28.6 7.5 50.5 25.4 70.2 19.7 21.8Depreciationandamortization 24.9 21.7 47.9 44.2 96.8 103.7 95.2EBITDA(a ) $ 168.1 $ 55.6 $ 308.7 $ 162.6 $ 393.8 $ 181.0 $ 226.8Lossonextinguishmentoflong-termdebt — 95.2 — 95.2 95.2 7.4 20.7Assetimpairmentchargesorwrite-offs(b) — — — — — — 9.9Netloss(gain)ondispositionofbusinessesandassets(c) 12.9 — 12.9 — — (0.6) 4.2

Restructuringandothercharges(d) 1.1 (0.1) 1.8 0.4 0.8 10.0 10.8Feespaidpursuanttoadvisoryagreement(e) — — — — — 25.4 4.7Otheritems(f) 0.3 0.6 2.2 1.9 2.2 38.4 0.8Adjusted EBITDA $ 182.4 $ 151.3 $ 325.6 $ 260.1 $ 492.0 $ 261.6 $ 277.9Inventoryrevaluation (12.9) (29.4) (3.2) 12.8 58.3 64.4 40.4Adjusted EBITDA excluding inventory

revaluation(g) $ 169.5 $ 121.9 $ 322.4 $ 272.9 $ 550.3 $ 326.0 $ 318.3

(a) WerefertoEBITDAinmakingoperatingdecisionsbecausewebelieveitprovidesmeaningfulsupplementalinformationregardingouroperationalperformance.OthercompaniesinourindustrymaydefineEBITDAdifferentlythanwedo.Asaresult,itmaybedifficulttouseEBITDA,orsimilarly-namedfinancialmeasuresthatothercompaniesmayuse,tocomparetheperformanceofthosecompaniestoourperformance.WecompensatefortheselimitationsbyprovidingreconciliationsofourEBITDAresultstoournetincome(loss),whichisdeterminedinaccordancewithGAAP.Seethe"SelectedSegmentInformation"inourQuarterlyReportonForm10-QforthequarterendedJune30,2016andourAnnualReportonForm10-KfortheyearendedDecember31,2015forfurtherdetailonEBITDAbyeachofourreportablesegments.

(b) Assetimpairmentchargesorwrite-offsfortheyearendedDecember31,2013relateprimarilytoa$9.2millionimpairmentchargeforfixedassetsatourpolycarbonatemanufacturingplantinStade,Germany.SeeNote7intheconsolidatedfinancialstatementsincludedinourAnnualReportonForm10-KfortheyearendedDecember31,2015forfurtherdiscussion.

Page 10: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

S-7

(c) DuringthethreeandsixmonthsendedJune30,2016,theCompanyrecordedanimpairmentchargefortheestimatedlossonsaleofourprimaryoperatingentityinBrazil,whichincludesbothlatexandautomotivebusinesses,ofapproximately$12.9million.SeeNote15inthecondensedconsolidatedfinancialstatementsinourQuarterlyReportonForm10-QforthequarterendedJune30,2016forfurtherdiscussion.Netloss(gain)ondispositionofbusinessesandassetsfortheyearsendedDecember31,2014and2013of$(0.6)millionand$4.2million,respectively,relatetothesaleoftheCompany'sexpandablepolystyrene,orEPS,business,whichclosedinSeptember2013,andforwhichacontingentgainof$0.6millionwasrecordedduringthefourthquarterof2014.SeeNote3intheconsolidatedfinancialstatementsinourAnnualReportonForm10-KfortheyearendedDecember31,2015forfurtherdiscussion.

(d) RestructuringandotherchargesforthethreeandsixmonthsendedJune30,2016relatetoemployeeterminationbenefitanddecommissioningchargesincurredinconnectionwiththeclosureofourAllyn'sPointlatexmanufacturingfacilityinGalesFerry,Connecticut,aswellasemploymentterminationbenefitchargesrelatedtotheexpectedeliminationofcertaincorporatefunctionspriortothesaleofourlatexandautomotivebusinessesinBrazil.RestructuringandotherchargesforthesixmonthsendedJune30,2015relateprimarilytothepolycarbonaterestructuringwithinourBasicPlastics&Feedstockssegment,forthereimbursementofdecommissioninganddemolitionchargestoDowinconnectionwiththeshutdownofitsFreeport,Texasfacility.SeeNote16tothecondensedconsolidatedfinancialstatementsincludedinourQuarterlyReportonForm10-QforthequarterendedJune30,2016forfurtherdiscussion.

RestructuringandotherchargesfortheyearendedDecember31,2015relateprimarilytothepolycarbonaterestructuringwithinourBasicPlastics&Feedstockssegmentnotedabove.RestructuringandotherchargesfortheyearsendedDecember31,2014and2013wereincurredprimarilyinconnectionwiththeshutdownofourlatexmanufacturingplantinAltona,AustraliaandtherestructuringwithinourBasicPlastics&Feedstockssegmentnotedabove.SeeNote20totheconsolidatedfinancialstatementsincludedinourAnnualReportonForm10-KfortheyearendedDecember31,2015forfurtherdiscussion.

NotethattheaccelerateddepreciationchargesincurredasapartoftheAllyn'sPointshutdown,andthe2014polycarbonaterestructuringwithinourBasicPlastics&Feedstockssegment,areincludedwithinthe"Depreciationandamortization"captionabove,andthereforearenotincludedasaseparateadjustmentwithinthiscaption.

(e) RepresentsfeespaidunderthetermsofouradvisoryagreementwithBainCapitalPrivateEquity,LP(the"AdvisoryAgreement").FortheyearendedDecember31,2014,thisincludesachargeof$23.3millionforfeesincurredinconnectionwiththeterminationoftheAdvisoryAgreement,pursuanttoitsterms,uponconsummationoftheCompany'sinitialpublicofferinginJune2014.SeeNote18totheconsolidatedfinancialstatementsincludedinourAnnualReportonForm10-KfortheyearendedDecember31,2015forfurtherdiscussion.

(f) OtheritemsforthethreeandsixmonthsendedJune30,2016relatetofeesincurredinconjunctionwiththeCompany'ssecondaryofferingscompletedinMay2016andMarch2016,respectively.SeeNote18inthecondensedconsolidatedfinancialstatementsinourQuarterlyReportonForm10-QforthequarterendedJune30,2016forfurtherdiscussion.OtheritemsforthethreeandsixmonthsendedJune30,2015andfortheyearsendedDecember31,2015and2014consistofcostsrelatedtotheprocessofchangingourcorporatenamefromStyrontoTrinseo.FortheyearendedDecember31,2014,thesecostsalsoincludeaone-time$32.5millionterminationpaymentmadetoDowinconnectionwiththeterminationofourLatexJVOptionAgreement.SeeNote18intheconsolidatedfinancialstatementsinourAnnualReportonForm10-KfortheyearendedDecember31,2015forfurtherdiscussion.

(g) SeethediscussionabovethistableforadescriptionofAdjustedEBITDAexcludinginventoryrevaluation.

(5) Workingcapitalisdefinedascurrentassetsminuscurrentliabilities.

(6) InApril2015,theFinancialAccountingStandardsBoard("FASB")issuedguidancethatrequiresdeferredfinancingfeesrelatedtoarecognizeddebtliabilitybepresentedonthebalancesheetasadirectreductionofthecarryingvalueofthatdebtliability,consistentwithdebtdiscounts.Therecognitionandmeasurementguidancefordeferredfinancingfeesarenotaffected.TheCompanyadoptedthisguidanceeffectiveJanuary1,2016.BalancesasofDecember31,2015presentedhereinhavebeenretrospectivelyadjustedtoreflectthisadoption,withresultingimpactstothecaptions"Totalassets"and"Totalliabilities,"consistentwithourQuarterlyReportonForm10-QforthequarterendedJune30,2016incorporatedbyreferenceherein.

Balancespresentedforallperiodswithinthe"Debt"captionabovereflectgrossdebtbalancesoutstandingateachperiodend,anddonotreflectareductionforthereclassificationofunamortizeddeferredfinancingfeesnotedabove.

Page 11: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

RISK FACTORS

An investment in our ordinary shares involves various risks. You should carefully consider the following risks and all of the other information contained inthis prospectus supplement and the accompanying prospectus before investing in our ordinary shares. In addition, you should read and consider the risk factorsassociated with our business included in the documents incorporated by reference in this prospectus supplement, including our Annual Report on Form 10-K forthe year ended December 31, 2015 and our Quarterly Report on Form 10-Q for the quarter ended June 30, 2016. See "Where You Can Find More Information."The risks described below and incorporated herein by reference are those which we believe are the material risks that we face. The trading price of our ordinaryshares could decline due to any of these risks, and you may lose all or part of your investment in our ordinary shares.

Risks Related to the Offering

Our share price could be extremely volatile, and, as a result, you may not be able to resell your ordinary shares at or above the price you paid for them.

SinceourinitialpublicofferinginJune2014,thepriceofanordinaryshare,asreportedontheNewYorkStockExchange,hasrangedfromalowof$11.92onNovember14,2014toahighof$60.02onAugust30,2016.Inaddition,thestockmarketingeneralhasbeenhighlyvolatile.Asaresult,themarketpriceofourordinarysharesislikelytobesimilarlyvolatile,andinvestorsinourordinarysharesmayexperienceadecrease,whichcouldbesubstantial,inthevalueoftheirshares,includingdecreasesunrelatedtoouroperatingperformanceorprospects,andcouldlosepartoralloftheirinvestment.Thepriceofourordinarysharescouldbesubjecttowidefluctuationsinresponsetoanumberoffactors,includingthosedescribedelsewhereinthisprospectussupplementortheaccompanyingprospectusandotherssuchas:

• variationsinouroperatingperformanceandtheperformanceofourcompetitors;

• actualoranticipatedfluctuationsinourquarterlyorannualoperatingresults;

• publicationofresearchreportsbysecuritiesanalystsaboutusorourcompetitorsorourindustry;

• ourfailureorthefailureofourcompetitorstomeetanalysts'projectionsorguidancethatweorourcompetitorsmaygivetothemarket;

• additionsanddeparturesofkeypersonnel;

• strategicdecisionsbyusorourcompetitors,suchasacquisitions,divestitures,spin-offs,jointventures,strategicinvestmentsorchangesinbusinessstrategy;

• thepassageoflegislationorotherregulatorydevelopmentsaffectingusorourindustry;

• speculationinthepressorinvestmentcommunity;

• changesinaccountingprinciples;

• terroristacts,actsofwarorperiodsofwidespreadcivilunrest;

• naturaldisastersandothercalamities;and

• changesingeneralmarketandeconomicconditions.

Inthepast,securitiesclassactionlitigationhasoftenbeeninitiatedagainstcompaniesfollowingperiodsofvolatilityintheirshareprice.Thistypeoflitigationcouldresultinsubstantialcostsanddivertourmanagement'sattentionandresources,andcouldalsorequireustomakesubstantialpaymentstosatisfyjudgmentsortosettlelitigation.

S-8

Page 12: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

There may be sales of a substantial amount of our ordinary shares after this offering by our current shareholders, and these sales could cause the price of ourordinary shares to fall.

AsofSeptember6,2016,therewere45,145,431ofourordinarysharesoutstanding,excludingtreasuryshares.Ofourissuedandoutstandingshares,alltheordinarysharessoldinourinitialpublicofferingandsubsequentregisteredofferings,includingthisoffering,willbefreelytransferable,exceptforanysharesheldbyour"affiliates,"asthattermisdefinedinRule144undertheSecuritiesAct.FollowingcompletionofthisofferingbasedonthesharesoutstandingasofSeptember6,2016,approximately0.5%ofouroutstandingordinaryshares,excludingtreasuryshares,willbebeneficiallyownedbyourofficersanddirectors.

Certainofourdirectors,executiveofficersandourParenthaveenteredintolock-upagreementswiththeunderwriter,whichregulatetheirsalesofourordinarysharesforaperiodof30daysafterthedateofthisprospectussupplement,subjecttocertainexceptions.

Salesofsubstantialamountsofourordinarysharesinthepublicmarketafterthisoffering,ortheperceptionthatsuchsaleswilloccur,couldadverselyaffectthemarketpriceofourordinarysharesandmakeitdifficultforustoraisefundsthroughsecuritiesofferingsinthefuture.Ofthesharestobeoutstandingaftertheoffering,thesharessoldinourinitialpublicofferingandsubsequentregisteredofferings,includingthesharesofferedbythisprospectussupplementandthesharesissuedunderour2014OmnibusIncentivePlan,areeligibleforimmediatesaleinthepublicmarketwithoutrestrictionbypersonsotherthanouraffiliates.

Inaddition,asofSeptember6,2016,wehad2,523,384ordinarysharesthatwereregisteredandreservedforissuanceunderour2014OmnibusIncentivePlan.

If you purchase shares in this offering, you will suffer immediate and substantial dilution.

AsofJune30,2016,ournettangiblebookvaluepersharewas$4.07.Ifyoupurchaseordinarysharesinthisoffering,youwillincurimmediateandsubstantialdilutionintheproformabookvalueofyourordinarysharesbecausethepricethatyoupaywillbesubstantiallygreaterthanthenettangiblebookvaluedeficiencypershareoftheordinarysharesyouacquire.Youwillexperienceadditionaldilutionupontheexerciseofoptionstopurchaseourordinaryshares,includingthoseoptionscurrentlyoutstandingandthosegrantedinthefuture,andtheissuanceofrestrictedstockunitsorotherequityawardsunderourequityincentiveplans.Totheextentweraiseadditionalcapitalbyissuingequitysecurities,ourshareholderswillexperiencesubstantialadditionaldilution.

The declaration, payment and amount of dividends or other cash distributions to our shareholders will be made at the discretion of our board of directors andwill depend on a number of factors.

OnJune21,2016,ourshareholdersauthorizedourboardofdirectorstomakerepaymentsofequityattimesandinamountssetbytheboard.OnJuly20,2016,wemadearepaymentofequityintheamountof$0.30pershareandanticipatemakingsimilarcashpaymentsinsubsequentquarters.See"DividendPolicy."However,therepaymentofequityorpaymentofdividendswillbeatthediscretionofourboardofdirectorsandourboardofdirectorsmay,initsdiscretion,reduceoreliminatethepaymentofdividendsorothercashdistributionstoourshareholders.Luxembourglawalsolimitstheamountsthatmaybedistributedtoourshareholders.UnderLuxembourglaw,annualcashdividendsmustbepaidfromstatutoryaccountingprofitsandapprovedbyshareholders.Unlessitreceivesdividendsfromitssubsidiaries,TrinseoS.A.willnothavestatutoryaccountingprofitswithoutdividendsfromitssubsidiariesasaholdingcompanywithoutoperations.Theabilitytopaydividendsonourordinarysharesisalsolimitedbyrestrictionsontheabilityofoursubsidiariestopaydividendsormakedistributionstous,includingrestrictionsunderthetermsofthecreditagreementgoverningoursubsidiaries'indebtedness.Additionally,oursubsidiariesarelocatedinavarietyofjurisdictions,which

S-9

Page 13: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

couldimposeadditionalrestrictionsorlimitationsontheabilityofthesesubsidiariestopaydividendsormakedistributionstous.

Anyfuturedeterminationtopaydividendsormakeotherdistributionstoourshareholderswillalsodependuponourresultsofoperations,financialcondition,capitalrequirementsandotherfactorsthatourboardofdirectorsdeemsrelevant.

Following the completion of this offering our Parent will no longer own ordinary shares of our Company and as of May 12, 2016 we are no longer a"controlled company" within the meaning of the NYSE rules and the rules of the SEC. We continue to rely on "controlled company" exemptions from certainNYSE and SEC corporate governance requirements during a one-year transition period.

AsofMay12,2016,ourParentnolongercontrolledamajorityofthevotingpowerofouroutstandingordinaryshares.BasedonthenumberofordinarysharesoutstandingasofSeptember6,2016,excludingtreasuryshares,ourParentcurrentlyownsapproximately23.6%ofourordinarysharesand,afterthecompletionofthisoffering,willnotownanyofourordinaryshares.SincetheconsummationofourofferingofordinarysharesinMay2016,wearenolongera"controlledcompany"withinthemeaningofthelistingrulesoftheNYSE.Consequently,undertheNYSElistingrules,wearerequiredtohavecompensationandnominatingandcorporategovernancecommitteescomposedentirelyofindependentdirectorsbyMay12,2017.Duringthistransitionperiod,wemaycontinuetoutilizetheavailableexemptionsfromcertaincorporategovernancerequirementsaspermittedbytheNYSElistingrules.Wecurrentlyrelyontheseexemptionsfromcorporategovernancerequirementsandweintendtorelyonsuchexemptionsforthedurationofthetransitionperiod.Accordingly,duringthetransitionperiod,youwillnothavethesameprotectionsaffordedtoshareholdersofcompaniesthataresubjecttoalloftheNYSEcorporategovernancestandards.

S-10

Page 14: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

Thisprospectussupplement,includinginformationincorporatedbyreferenceherein,containsforward-lookingstatementsincluding,withoutlimitation,statementsconcerningplans,objectives,goals,projections,strategies,futureeventsorperformance,andunderlyingassumptionsandotherstatements,whicharenotstatementsofhistoricalfacts.Forward-lookingstatementsmaybeidentifiedbytheuseofwordslike"expect,""anticipate,""intend,""forecast,""outlook,""will,""may,""might,""potential,""likely,""target,""plan,""contemplate,""seek,""attempt,""should,""could,""would"orexpressionsofsimilarmeaning.Forward-lookingstatementsreflectmanagement'sevaluationofinformationcurrentlyavailableandarebasedonourcurrentexpectationsandassumptionsregardingourbusiness,theeconomyandotherfutureconditions.Becauseforward-lookingstatementsrelatetothefuture,theyaresubjecttoinherentuncertainties,risksandchangesincircumstancesthataredifficulttopredict.Specificfactorsthatmayimpactperformanceorotherpredictionsoffutureactionshave,inmanybutnotallcases,beenidentifiedinconnectionwithspecificforward-lookingstatements.Ouractualresultsmaydiffermateriallyfromthosecontemplatedbytheforward-lookingstatements.Theyareneitherstatementsofhistoricalfactnorguaranteesorassurancesoffutureperformance.Importantfactorsthatcouldcauseactualresultstodiffermateriallyfromthoseintheforward-lookingstatementsincludeeconomic,business,competitive,marketandregulatoryconditionsandthefollowing:

• ourcurrentlevelofindebtedness;

• thestabilityofourjointventures;

• changesinregulationsinthejurisdictionswherewemanufacture;

• lawsuitsresultingfromproductsoroperations;

• volatilityincostsordisruptioninthesupplyoftherawmaterialsutilizedforourproducts;

• hazardsassociatedwithchemicalmanufacturing;

• thecompetitivenatureofourendmarkets;

• ourcontinuedrelianceonourrelationshipwithTheDowChemicalCompany;

• ourcompliancewithenvironmental,healthandsafetylaws;

• conditionsintheglobaleconomyandcapitalmarkets;

• anydisruptionsinproductionatourmanufacturingfacilities;

• increasesinthecostofenergy;

• ourabilitytomaintainthenecessarylicensesandpermitsweneedforouroperations;

• failuretomaintainaneffectivesystemofinternalcontrols;

• currentinsurancenotcoveringallpotentialexposures;

• theoutcomeofcertaingovernmentinvestigations;

• changesinlawsandregulationsapplicabletoourbusiness;

• ourdependenceuponkeyexecutivemanagementandanyinabilitytoattractandretainotherqualifiedmanagementpersonnel;

• fluctuationsincurrencyexchangerates;

• strategicacquisitionsaffectingcurrentoperations;

• ourabilitytoreceivedistributionsfromoursubsidiariesandjointventures;

S-11

Page 15: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

• theoutcomeoftheongoinginvestigationinvolvingoneofourjointventures;

• thelossofcustomers;

• anyinabilitytocontinuetechnologicalinnovationandsuccessfulintroductionofnewproducts;

• anyinabilitytoprotectourtrademarks,patentsorotherintellectualpropertyrights;

• datasecuritybreaches;

• failureofourassumptionsandprojectionstobeaccurate;

• localbusinessrisksindifferentcountriesinwhichweoperate;

• seasonalityofourbusiness;

• adverseeventsaffectingthestabilityandstandingoftheEuropeanUnion;and

• otherrisksdescribedinthe"RiskFactors"sectionofthisprospectussupplement.

Wederivemanyofourforward-lookingstatementsfromouroperatingbudgetsandforecasts,whicharebaseduponmanydetailedassumptions.Whilewebelievethatourassumptionsarereasonable,wecautionthatitisverydifficulttopredicttheimpactofknownfactors,anditisimpossibleforustoanticipateallfactorsthatcouldaffectouractualresults.Importantfactorsthatcouldcauseactualresultstodiffermateriallyfromourexpectations,orcautionarystatements,aredisclosedunderthesectionentitled"RiskFactors"andthesectionsentitled"Management'sDiscussionandAnalysisofFinancialConditionandResultsofOperations"fromourAnnualReportonForm10-KandfromourQuarterlyReportsonForm10-Q,incorporatedbyreferenceintothisprospectussupplement.Allwrittenandoralforward-lookingstatementsattributabletous,orpersonsactingonourbehalf,areexpresslyqualifiedintheirentiretybythecautionarystatementsaswellasothercautionarystatementsthataremadefromtimetotimeinourotherpubliccommunications.Youshouldevaluateallforward-lookingstatementsmadeinthisprospectussupplementandthedocumentsincorporatedbyreferencehereininthecontextoftheserisksanduncertainties.

Wecautionyouthattheimportantfactorsreferencedabovemaynotcontainallofthefactorsthatareimportanttoyou.Inaddition,wecannotassureyouthatwewillrealizetheresultsordevelopmentsweexpectoranticipateor,evenifsubstantiallyrealized,thattheywillresultintheconsequencesoraffectusorouroperationsinthewayweexpect.Theforward-lookingstatementsincludedinthisprospectussupplementandthedocumentsincorporatedbyreferencehereinaremadeonlyasofthedateoftheapplicabledocument.Weundertakenoobligationtopubliclyupdateorreviseanyforward-lookingstatementasaresultofnewinformation,futureeventsorotherwise,exceptasotherwiserequiredbylaw.

S-12

Page 16: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

USE OF PROCEEDS

Wewillnotreceiveanyproceedsfromthesaleofourordinarysharesbythesellingshareholder.

See"SellingShareholder"and"Underwriting."

S-13

Page 17: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

MARKET PRICE OF OUR ORDINARY SHARES

OurordinaryshareshavebeenlistedontheNewYorkStockExchangeunderthesymbol"TSE"sinceJune12,2014.Priortothattime,therewasnopublicmarketforourordinaryshares.ThefollowingtablesetsforthfortheperiodsindicatedthehighandlowsalepricesofourordinarysharesontheNewYorkStockExchange.

Arecentreportedclosingpriceforourordinarysharesissetforthonthecoverpageofthisprospectussupplement.AmericanStockTransferandTrustCompany,LLCisthetransferagentandregistrarforourordinaryshares.AsofSeptember6,2016,therewere2holdersofrecordofourordinaryshares.

S-14

Fiscal Quarter High Low 2014: Secondquarter(fromJune12,2014) $ 22.99 $ 20.00Thirdquarter $ 21.78 $ 15.54Fourthquarter $ 18.84 $ 11.922015: Firstquarter $ 20.76 $ 14.14Secondquarter $ 30.44 $ 19.42Thirdquarter $ 33.69 $ 23.46Fourthquarter $ 32.96 $ 24.802016: Firstquarter $ 39.23 $ 21.92Secondquarter $ 49.72 $ 36.19Thirdquarter(throughSeptember19,2016) $ 60.02 $ 41.60

Page 18: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

DIVIDEND POLICY

Wemadearepaymentofequityof$0.30perordinarysharepayableincashonJuly20,2016toourshareholdersofrecordasofthecloseofbusinessonJuly6,2016.Priortothisdistribution,wehadnotdeclaredorpaiddividendsorothercashdistributionsonourordinarysharessincebecomingapubliccompany.

Luxembourglawpermitscashdistributionstoshareholdersthroughtherepaymentofshareholders'equity.Theamountofthisdistributionmaynotcausetheannualnon-consolidatedstatutorynetassetsofTrinseoS.A.tofallbelowtheaggregateofitsissuedandsubscribedsharecapitalandlegalreserves.Weexpectthatourreservesavailablefordistributionwillpermitustomakecashdistributionstoourshareholdersinto2017.OurshareholdershaveauthorizedourboardofdirectorstomakeequityrepaymentsinamountsandinfrequenciesdeterminedbytheboardofdirectorsandatalltimesincompliancewithLuxembourglaw.Nevertheless,thisauthorizationfromourshareholdersdoesnotrequirethatourboardofdirectorsdeclareandmakeanequityrepayment,orguaranteethattheywillcontinuedosointhefuture.

PaymentofdividendsonourordinarysharesissubjecttothedeterminationanddeclarationbyourboardofdirectorsandtheapprovalofourshareholdersunderLuxembourglaw.Luxembourglawalsolimitstheamountsthatmaybedistributedtoourshareholders.UnderLuxembourglaw,cashdividendsmustbepaidfromstatutoryaccountingprofitsandapprovedbyshareholders.Unlessitreceivesdividendsfromitssubsidiaries,TrinseoS.A.willnothavestatutoryaccountingprofitsasaholdingcompanywithoutoperations.

Theabilitytopaydividendsonourordinarysharesisalsolimitedbyrestrictionsontheabilityofoursubsidiariestopaydividendsormakedistributionstous,includingrestrictionsunderthetermsofthecreditagreementgoverningoursubsidiaries'indebtedness.Additionally,oursubsidiariesarelocatedinavarietyofjurisdictions,whichcouldimposeadditionalrestrictionsorlimitationsontheabilityofthesesubsidiariestopaydividendsormakedistributionstous.

Althoughweexpecttocontinuetomakequarterlycashdistributionstoshareholdersasrepaymentsofequityordividends,anyfuturedeterminationtopaydividendsormakeotherdistributionstoourshareholderswillbeatthediscretionofourboardofdirectors,subjecttocompliancewithcovenantsincurrentandfutureagreementsgoverningourindebtednessandapplicableLuxembourglaw,andwilldependuponourresultsofoperations,financialcondition,capitalrequirementsandotherfactorsthatourboardofdirectorsdeemsrelevant.

S-15

Page 19: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

DESCRIPTION OF SHARE CAPITAL

Thefollowingisasummaryofsomeofthetermsofourordinaryshares,basedonourarticlesofassociation.

Thefollowingsummaryissubjectto,andisqualifiedinitsentiretybyreferenceto,theprovisionsofourarticlesofassociation,theformofwhichhasbeenfiledasanexhibittotheregistrationstatementofwhichthisprospectusisapart.Youmayobtaincopiesofourarticlesofassociationasdescribedunder"WhereYouCanFindMoreInformation"inthisprospectus.

General

TrinseoS.A.isaLuxembourgpubliclimitedliabilitycompany(société anonyme ).Thecompany'slegalnameis"TrinseoS.A."TrinseoS.A.wasincorporatedonJune3,2010asaLuxembourgprivatelimitedliabilitycompany(société à responsabilité limitée )andwasconvertedintoaLuxembourgpubliclimitedliabilitycompanyonApril29,2011.

TrinseoS.A.isregisteredwiththeLuxembourgRegistryofTradeandCompaniesundernumberB153.549.TrinseoS.A.hasitsregisteredofficeat4,rueLouHemmer,L-1748Luxembourg,GrandDuchyofLuxembourg.

ThecorporatepurposeofTrinseoS.A.isstatedinArticle3ofitsarticlesofassociation.Thispurposeincludestheacquisitionofparticipations,inLuxembourgorabroad,inanycompanyorenterpriseinanyformwhatsoever,andthemanagement,developmentandsaleofthoseparticipations.TrinseoS.A.mayacquireandsell,bysubscription,purchaseandexchangeorinanyothermanner,anystock,sharesandotherparticipationsecurities,bonds,debentures,certificatesofdepositandotherdebtinstrumentsand,moregenerally,anysecuritiesandfinancialinstrumentsissuedbyanypublicorprivateentity.Itmayparticipateinthecreation,development,managementandcontrolofanycompanyorenterprise.Furthermore,itmayinvestintheacquisitionandmanagementofaportfolioofpatentsorotherintellectualpropertyrightsofanynatureororigin.

Additionally,TrinseoS.A.mayborrowinanyformandproceedtoissuedebtbyprivateorpublicofferingsofbonds,convertiblebondsanddebenturesoranyothersecuritiesorinstrumentsitdeemsfit.Ingeneral,TrinseoS.A.maygrantassistance(bywayofloans,advances,guaranteesorsecuritiesorotherwise)tocompaniesorotherenterprisesinwhichTrinseoS.A.hasaninterestorwhichformpartofthegroupofcompaniestowhichTrinseoS.A.belongsoranyotherentityasTrinseoS.A.maydeemfit.

TrinseoS.A.mayuseanytechniques,legalmeansandinstrumentstomanageitsinvestmentsintheparticipationsefficientlyandprotectitselfagainstcreditrisks,currencyexchangeexposure,interestraterisks,andotherrisk.Finally,itcanalsoperformallcommercial,financialorindustrialoperationandanytransactionwithrespecttorealestateormovableproperty,whichdirectlyorindirectlysupportsorrelatestoitscorporatepurpose.

Share Capital

AsofSeptember6,2016,ourissuedsharecapitalamountsto$487,779.34,representedby48,777,934issuedordinaryshares,including3,632,503ordinarysharesheldintreasury,eachwithanominalvalueof$0.01pershare.Allissuedshareswerefullypaid.OurtreasuryshareshavenovotingrightsoranyrightstoreceivedividendsorotherdistributionsmadebytheCompany.

Ourarticlesofassociationauthorizeourboardofdirectorstoissueordinaryshareswithinthelimitsoftheauthorizedsharecapitalatsuchtimesandonsuchtermsasourboardofdirectorsmaydecideforaperiodcommencingonthedateofpublicationofouramendedarticlesofassociation(i.e.,June11,2014)andendingfiveyearsafterthedateonwhichtheminutesoftheshareholders'

S-16

Page 20: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

meetingapprovingsuchauthorizationarepublishedintheLuxembourgofficialgazette(RecueildesSociétésetAssociations(RESA ))(unlesssuchperiodisextended,amendedorrenewed).Accordingly,ourboardisauthorizedtoissueupto50,000,000,000ordinarysharesduringsuchperiod.Wecurrentlyintendtoseekrenewalsand/orextensionsasrequiredfromtimetotime.

Ourauthorizedsharecapitalisdeterminedbyourarticlesofassociation,asamendedfromtimetotime,andmaybeincreased,reducedorextendedbyamendingthearticlesofassociationbyapprovaloftherequisitetwo-thirdsmajorityofthevotesataquorateextraordinarygeneralshareholders'meeting.

UnderLuxembourglaw,ourshareholdersbenefitfromapre-emptivesubscriptionrightontheissuanceofsharesforcashconsideration.However,ourshareholdershave,inaccordancewithLuxembourglaw,authorizedtheboardofdirectorstosuppress,waiveorlimitanypre-emptivesubscriptionrightsofshareholdersprovidedbylawtotheextenttheboarddeemssuchsuppression,waiverorlimitationadvisableforanyissuanceorissuancesofshareswithinthescopeofourauthorizedsharecapital.Suchsharesmaybeissuedabove,atorbelowmarketvaluebutinanyeventnotbelowthenominalvalueperordinaryshareaswellasbywayofincorporationofavailablereserves(includingpremium).

Theboardofdirectorswillresolveonasharesissuanceforwhichitintendstowaiveorlimitanypre-emptivesubscriptionrightsofshareholdersinaccordancewiththequorumandvotingthresholdssetforthinourarticlesofassociation.Theboardofdirectorswillalsoresolveontheapplicableproceduresandtimelinestowhichitwill,orhasto,subjectsuchissuance.Iftheproposaloftheboardofdirectorstoissuenewsharesexceedsthelimitsoftheourauthorizedsharecapital,theboardofdirectorsmustthenconvenetheshareholderstoanextraordinarygeneralmeetingtobeheldinthepresenceofaLuxembourgnotaryforthepurposeofincreasingtheissuedsharecapitalaccordinglyandprioritizingtheissueofsharesexceedingthelimitoftheauthorizedsharecapital.Thismeetingwillbesubjecttothetwo-thirdmajorityofthevotesataquorateextraordinarygeneralshareholders'meeting.Ifacapitalcallproposedbytheboardofdirectorsconsistsofanincreaseintheshareholders'commitments,theboardofdirectorsmustthenconvenetheshareholderstoanextraordinarygeneralmeetingtobeheldinthepresenceofaLuxembourgnotaryforsuchpurpose.Thismeetingwillbesubjecttotheunanimousconsentoftheshareholders.

Form and Transfer of Shares

OurordinarysharesareissuedinregisteredformonlyandarefreelytransferableunderLuxembourglawandourarticles,providedthatourboardofdirectorsmayimposetransferrestrictionsforsharesthatareregistered,listed,quoted,dealtin,orhavebeenplacedincertainjurisdictionsincompliancewiththeapplicablerequirements.LuxembourglawdoesnotimposeanylimitationsontherightsofLuxembourgornon-Luxembourgresidentstoholdorvoteourordinaryshares.UnderLuxembourglaw,theownershipofregisteredsharesisestablishedbytheinscriptionofthenameoftheshareholderandthenumberofsharesheldbyhimorherintheshareholdersregister(registre des actionnaires )heldbyusatourregisteredofficeinLuxembourg.Atalltimes,wekeepacopyoftheshareholdersregisterinatourregisteredofficeinLuxembourg.Eachtransferofsharesshallbepromptlymadeknowntousaswellasanychangestotheshareholdersregisterandwerecordsuchchangeintheshareholdersregisterheldatourregisteredoffice.ForpurposesofLuxembourglaw,ownershipofourordinarysharesisevidencedthroughregistrationfromtimetotimeintheshareholdersregisterheldatourregisteredoffice,andsuchregistrationisameansofevidencingtitletotheshares.Fortheavoidanceofdoubt,incaseofdiscrepancybetweentheshareholdersregisterheldbyusatourregisteredofficeinLuxembourgandanyotherseparateregisterforthesharesheldbyentitiesinLuxembourgorinotherjurisdictions,theshareholdersregister(registre des actionnaires )heldbyusatourregisteredofficeinLuxembourgshallprevail.

S-17

Page 21: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Withoutprejudicetotheconditionsfortransferbybookentrywheresharesarerecordedintheshareholderregisteronbehalfofoneormorepersonsinthenameofadepository,eachtransferofsharesshallbeeffectedbywrittendeclarationoftransfertoberecordedintheshareholderregister,suchdeclarationtobedatedandsignedbythetransferorandthetransferee,orbytheirdulyappointedagents.Wemayacceptandenterintotheshareholderregisteranytransferofshareseffectedpursuanttoanagreementoragreementsbetweenthetransferorandthetransferee,trueandcompletecopiesofwhichhavebeendeliveredtous.

Ourarticlesofassociationprovidethatwemayappointregistrarsindifferentjurisdictions,eachofwhommaymaintainaseparateregisterforthesharesenteredinsuchregisterandtheholdersofsharesshallbeenteredintooneoftheregistersandpromptlymadeknowntousforpurposesofregistrationintheshareholders'register(registre des actionnaires )heldbyusatourregisteredofficeinLuxembourg.Shareholdersmayelecttobeenteredintooneoftheseregistersandtotransfertheirsharestoanotherregistersomaintained.Entriesintheseregistersisreflectedintheshareholders'registermaintainedatourregisteredoffice.

Inaddition,ourarticlesofassociationalsoprovidethatourordinarysharesmaybeheldthroughasecuritiessettlementsystemoraprofessionaldepositoryofsecurities.Ordinarysharesheldinsuchmannerhavethesamerightsandobligationsasordinarysharesrecordedinourshareholders'register.Furthermore,ordinarysharesheldthroughasecuritiessettlementsystemoraprofessionaldepositoryofsecuritiesmaybetransferredinaccordancewithcustomaryproceduresforthetransferofsecuritiesinbook-entryform,thetransferbeingeffectiveuponnotificationtousandregistrationintheshareholders'register(registre desactionnaires )heldbyusatourregisteredofficeinLuxembourg.

Issuance of Shares

PursuanttotheLuxembourglawoncommercialcompaniesdatedAugust10,1915,asamended,whichwerefertoastheLuxembourgCorporateLaw,theissuanceofordinarysharesrequirestheamendmentofourarticlesofassociationbyapprovaloftherequisitetwo-thirdsmajorityofthevotesataquorateextraordinarygeneralshareholders'meeting(see"—GeneralMeetingofShareholders"and"—AmendmenttotheArticlesofAssociation").ThegeneralmeetingmaydetermineanauthorizedsharecapitalandauthorizetheboardofdirectorstoissueordinarysharesuptothemaximumamountofsuchauthorizedsharecapitalforamaximumperiodoffiveyearsasfromthedateofpublicationintheLuxembourgofficialgazette(Recueil Electronique des Sociétés et Associations (RESA))oftheminutesoftherelevantgeneralmeeting.Thegeneralmeetingofshareholdersmayamend,reneworextendsuchauthorizedsharecapitalandsuchauthorizationtotheboardofdirectorstoissueshares.

Ourarticlesprovidethatnofractionalsharesshallbeissued.

Ourordinaryshareshavenoconversionrightsandtherearenoredemptionorsinkingfundprovisionsapplicabletoourordinaryshares.

Pre-Emptive Rights

Unlesslimited,waivedorcancelledbyourboardofdirectors,holdersofourordinaryshareshaveaproratapre-emptiverighttosubscribeforanynewsharesissuedforcashconsideration.Ourarticlesofassociationprovidethatpre-emptiverightscanbelimited,waivedorcancelledbyourboardofdirectorsforaperiodendingonthefifthanniversaryofthedateonwhichtheminutesoftheshareholders'meetingapprovingsuchauthorizationarepublishedintheLuxembourgOfficialGazette(RESA ),meaningJune11,2019,unlesssuchperiodisextended,amendedorrenewed,intheeventofanincreaseofthesharecapitalbytheboardofdirectorswithinthelimitsoftheauthorizedsharecapital.

S-18

Page 22: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Repurchase of Shares

Wecannotsubscribeforourownordinaryshares.

Wemay,however,repurchaseissuedordinarysharesorhaveanotherpersonrepurchaseissuedordinarysharesforouraccount,subjecttothefollowingconditions:

• priorauthorizationbyasimplemajorityvoteatanordinarygeneralmeetingofshareholders,whichauthorizationsetsforththetermsandconditionsoftheproposedrepurchaseandinparticularthemaximumnumberofordinarysharestoberepurchased,thedurationoftheperiodforwhichtheauthorizationisgiven(whichmaynotexceedfiveyears)and,inthecaseofrepurchaseforconsideration,theminimumandmaximumconsiderationpershare;

• therepurchasemaynotreduceournetassetsonanon-consolidatedbasistoalevelbelowtheaggregateoftheissuedandsubscribedsharecapitalandthereservesthatwemustmaintainpursuanttoLuxembourglaworourarticlesofassociation;

• onlyfullypaid-upsharesmayberepurchased;and

• theoffertoacquiremustbemadeonthesameconditionstoallsimilarlysituatedshareholders,exceptforacquisitions:(i)decidedunanimouslyatageneralmeetingatwhichalltheshareholderswerepresentorrepresented;or(ii)bylistedcompaniesonthestockexchange.

Thegeneralmeetingofshareholdersauthorizedtheboardofdirectorstorepurchaseupto4.5millionofitsordinaryshares.Theauthorizationisvalidforaperiodendingontheearlierof2yearsfromthedateofthedecision(meaninguntilJune21,2018)orthedateofitsrenewalbyasubsequentgeneralmeetingofshareholders.Pursuanttosuchauthorization,theboardofdirectorsisauthorizedtoacquireandsellordinarysharesintheCompanyundertheconditionssetforthinArticle49-2oftheLuxembourgCorporateLaw.Suchpurchasesandsalesmaybecarriedoutforanyauthorizedpurposeoranypurposethatisauthorizedbythelawsandregulationsinforce.

Thepurchasepriceperordinarysharetobepaidshallnotrepresentmorethan$1,000andshallnotbelessthan$1.00.

Inaddition,pursuanttoLuxembourglaw,TrinseoS.A.maydirectlyorindirectlyrepurchaseordinarysharesbydecisionofourboardofdirectorswithoutthepriorapprovalofthegeneralmeetingofshareholdersifsuchrepurchaseisdeemedbytheboardofdirectorstobenecessarytopreventseriousandimminentharmtousoriftheacquisitionofshareshasbeenmadeinviewofthedistributionthereoftoemployees.

Capital Reduction

Ourarticlesofassociationprovidethatourissuedsharecapitalmaybereduced,subjecttotheapprovalorpriorauthorizationoftherequisitetwo-thirdsmajorityofthevotesataquorateextraordinarygeneralshareholders'meeting.

General Meeting of Shareholders

AnyregularlyconstitutedgeneralmeetingofshareholdersofTrinseoS.A.representstheentirebodyofshareholdersofTrinseoS.A.

Eachofourordinarysharesentitlestheholderthereoftoattendourgeneralmeetingofshareholders,eitherinpersonorbyproxy,toaddressthegeneralmeetingofshareholders,andtoexercisevotingrights,subjecttotheprovisionofourarticlesofassociation.Eachordinaryshareentitlestheholdertoonevoteatageneralmeetingofshareholders.Ourarticlesofassociationprovidethatourboardofdirectorsshalladoptallotherregulationsandrulesconcerningtheattendancetothe

S-19

Page 23: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

generalmeeting,andavailabilityofaccesscards,proxyformsinordertoenableshareholderstoexercisetheirrighttovoteasitdeemsfit.

Ashareholdermayparticipateatanygeneralmeetingofshareholdersbyappointinganotherperson(whoneednotbeashareholder)ashisproxy,theappointmentofwhichshallbeinwriting.Ourarticlesofassociationprovidethatourboardofdirectorsmaydetermineadatebywhichweorouragentsmusthavereceiveddulycompletedproxyformsinorderforsuchformtobetakenintoaccountatthegeneralmeeting.

Whenconveningageneralmeetingofshareholders,wewillpublishanotice(whichmustbepublishedatleast30dayspriortothegeneralmeetingdate)intheRESA ,andinaLuxembourgnewspaper.OurarticlesofassociationprovidethatnoticeoftheconveningofthegeneralmeetingofshareholderswillalsobeprovidedinaformofeasilyaccessiblemediawhichisreasonablyexpectedtoberelieduponfortheeffectivedisseminationofinformationtothepublicandthroughouttheEuropeanEconomicArea.

Therightofashareholdertoparticipateinageneralmeetingofshareholdersandexercisevotingrightsisdeterminedbyreferencetothenumberofsharesheldbytheshareholderatmidnight(00:00)ontherecorddate,whichmaybethedayfalling14daysbeforethedateofthegeneralmeetingofshareholdersoranotherdaysetbyourboardofdirectorsandmentionedintheconveningnotice.Eachshareholdershall,onorbeforetherecorddate,indicatetousitsintentiontoparticipateinpersonatthegeneralmeetingofshareholders.TrinseoS.A.determinesthemannerinwhichthisdeclarationismade.Proofofthequalificationasashareholdermayonlybethosenecessarytoensuretheidentificationofshareholders.OurBoardmaydetermineanyotherconditionsthatmustbefulfilledbytheshareholdersforthemtotakepartinanygeneralmeetingofshareholdersinpersonorinproxy.

TheannualordinarygeneralmeetingofshareholdersofTrinseoS.A.isheldat2:00p.m.(CentralEuropeanTime)onthefirstMondayofJuneofeachyearattheregisteredofficeoftheCompanyorinanyotherplacewithinthemunicipalityoftheregisteredofficeoftheCompanyintheGrandDuchyofLuxembourg,asnoticedtotheshareholders,orabroad,iftheboardofdirectorsconsidersinitsabsoluteandfinaljudgment,thatexceptionalcircumstancessorequire.IfthatdayisnotabusinessdayinLuxembourg,themeetingwillbeheldonthenextfollowingbusinessday.

Luxembourglawprovidesthattheboardofdirectorsisobligedtoconveneageneralmeetingofshareholdersifshareholdersrepresenting,intheaggregate,10%oftheissuedsharecapitalsorequestinwritingwithanindicationofthemeetingagenda.Insuchcase,thegeneralmeetingofshareholdersmustbeheldwithinonemonthoftherequest.Iftherequestedgeneralmeetingofshareholdersisnotheldwithinonemonth,shareholdersrepresenting,intheaggregate,10%oftheissuedsharecapitalmaypetitionthecompetentpresidentofthedistrictcourtinLuxembourgtohaveacourtappointeeconvenethemeeting.Luxembourglawprovidesthatshareholdersrepresenting,intheaggregate,10%oftheissuedsharecapitalmayrequestthatadditionalitemsbeaddedtotheagendaofageneralmeetingofshareholders.ThatrequestmustbemadebyregisteredmailsenttotheregisteredofficeoftheCompanyatleastfivedaysbeforethegeneralmeetingofshareholders.

Voting Rights

Eachshareentitlestheholderthereoftoonevoteatageneralmeetingofshareholders.Luxembourglawdistinguishesordinaryresolutionsandextraordinaryresolutions.

Extraordinaryresolutionsrelatetoproposedamendmentstothearticlesofassociationandcertainotherlimitedmatters.Allotherresolutionsareordinaryresolutions.

Ordinary Resolutions

Pursuanttoourarticlesofassociation,foranyordinaryresolutionstobeconsideredatageneralmeeting,thequorumatsuchmeetingmustbeatleastfiftypercent(50%)oftheissuedsharecapitaloftheCompany(unlessotherwisemandatorilyrequiredbylaw)andsuchordinaryresolutionsshallbeadoptedbyasimplemajorityofvotesvalidlycastonsuchresolution.Abstentionsarenotconsidered"votes."

S-20

Page 24: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Extraordinary Resolutions

Extraordinaryresolutionsarerequiredforanyofthefollowingmatters,amongothers:(a)anincreaseordecreaseoftheauthorizedorissuedcapital,(b)alimitationorexclusionofpreemptiverights,(c)approvalofastatutorymergerorde-merger(scission),(d)dissolutionandliquidationofTrinseoS.A.and(e)anyandallamendmentstoourarticlesofassociation.Pursuanttoourarticlesofassociation,foranyextraordinaryresolutionstobeconsideredatageneralmeetingthequorumshallbeatleastone-half(50%)oftheissuedsharecapitaloftheCompanyunlessotherwisemandatorilyrequiredbylaw.Ifthesaidquorumisnotpresent,asecondmeetingmaybeconvenedatwhichnoquorumconditionshallapply.Anyextraordinaryresolutionshallbeadoptedataquorategeneralmeeting(saveasotherwiseprovidedbymandatorylaw)atleasttwo-thirds(2/3)majorityofthevotesvalidlycastonsuchresolution.Abstentionsarenotconsideredvotes.

Appointment and Removal of Directors

Membersofourboardofdirectorsmaybeelectedbyordinaryresolutionatageneralmeetingofshareholdersatasimplemajorityvoteofshareholders.Ourarticlesofassociationprovidethatalldirectorsareelectedforaperiodofthreeyears,withtheboarddividedintothreeclassesofapproximatelyequalsize.Attheannualgeneralmeetingofshareholders,oneclassperyearwillbeelected.Anydirectormayberemovedwithorwithoutcausebyordinaryresolutionatageneralmeetingofshareholders.Ourarticlesofassociationprovidethatincaseofavacancy,theotherdirectorsshallfillsuchvacancyonaprovisionalbasis,until(i)thedecisionisratifiedor(ii)anewdirectoriselected,byanordinaryresolutionofthenextgeneralmeetingofshareholders.Thedirectorsshallbeeligibleforre-electionindefinitely.

NeitherLuxembourglawnorourarticlesofassociationcontainanyrestrictionsastothevotingofoursharesbynon-Luxembourgresidents.

Amendment to the Articles of Association

Shareholder Approval Requirements

Luxembourglawrequiresthatanamendmentofthearticlesofassociationbemadebyextraordinaryresolution,suchdecisionbeingtakenwithaqualifiedmajorityofvotes.Theagendaofthegeneralmeetingofshareholdersmustindicatetheproposedamendmentstothearticlesofassociation.

Formalities

AnyresolutionstoamendourarticlesofassociationmustbetakenbeforeaLuxembourgnotaryandsuchamendmentsmustbepublishedinaccordancewithLuxembourglaw.

Merger and De-Merger

Amergerorde-mergerbyabsorptionwherebyoneLuxembourgcompanyafteritsdissolutionwithoutliquidationtransferstoanothercompanyallofitsassetsandliabilitiesinexchangefortheissuanceofsharesintheacquiringcompanytotheshareholdersofthecompanybeingacquired,oramergerorde-mergereffectedbytransferofassetstoanewlyincorporatedcompany,must,inprinciple,beapprovedatageneralmeetingbyanextraordinaryresolutionoftheLuxembourgcompany,andthegeneralmeetingmustbeheldbeforeanotary.

Dissolution and Liquidation

Intheeventofourdissolution,liquidation,orwinding-uptheassetsremainingafterallowingforthepaymentofallliabilitiesofthecompanywillbepaidouttotheshareholdersprorataaccordingtotheirrespectiveshareholdings.Generallythedecisionstodissolve,liquidate,orwind-uprequirethepassingofanextraordinaryresolutionatageneralmeetingofourshareholders,andsuchmeetingmust

S-21

Page 25: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

beheldbeforeanotary.ShareholdersofaLuxembourgpubliclimitedliabilitycompanyhavetheirliabilitylimitedtothecapitalcontributioninrespectofthesharestheysubscribedandpaidorcommittedtopayfor.However,distributionofdividendsbytheCompanymaynotresultinareductionoftheCompany'snetassetvaluebelowtheamountofitscapital.

No Appraisal Rights

NeitherLuxembourglawnorourarticlesofassociationprovideforanyappraisalrightsofdissentingshareholders.

Dividend Distributions

SubjecttoLuxembourglaw,ifandwhenadividenddistributionisdeclaredbythegeneralmeetingofshareholdersortheboardofdirectorsinthecaseofinterimdividenddistributions,eachordinaryshareisentitledtoparticipateequallyinsuchdistributionoffundslegallyavailableforsuchpurposes.Pursuanttoourarticlesofassociation,thegeneralmeetingofshareholdersmayapproveadividenddistributionandtheboardofdirectorsmaydeclareaninterimdividenddistribution,totheextentpermittedbyLuxembourglaw.

Declaredandunpaiddividenddistributionsheldbyusfortheaccountoftheshareholdersshallnotbearinterest.UnderLuxembourglaw,claimsforunpaiddividenddistributionswilllapseinourfavorfiveyearsafterthedatesuchdividenddistributionwasdeclared.

Annual Accounts

UnderLuxembourglaw,theboardofdirectorsmustprepareunconsolidatedannualaccounts,i.e.,aninventoryoftheassetsandliabilitiesofTrinseoS.A.togetherwithabalancesheetandaprofitandlossaccounteachyear.Ourboardofdirectorsmustalsoannuallyprepareconsolidatedaccountsandmanagementreportsontheunconsolidatedannualaccountsandconsolidatedaccounts.Theunconsolidatedannualaccounts,theconsolidatedaccounts,themanagementreportandtheauditor'sreportsmustbeavailableforinspectionbyshareholdersuponrequestandfreeofcharge,atourregisteredofficeatleast15calendardayspriortothedateoftheannualordinarygeneralmeetingofshareholders.

Theunconsolidatedannualaccountsandtheconsolidatedaccounts,afterapprovalbytheannualordinarygeneralmeetingofshareholders,willbefiledwiththeLuxembourgRegistryofTradeandCompanies.

Information Rights

Luxembourglawgivesshareholderslimitedrightstoinspectcertaincorporaterecords8calendardayspriortothedateoftheannualordinarygeneralmeetingofshareholders,includingtheunconsolidatedannualaccountswiththelistofdirectorsandauditors,theconsolidatedaccounts,thenotestotheannualaccountsandtheconsolidatedaccounts,alistofshareholderswhosesharesarenotfullypaid-up,themanagementreportsandtheauditor'sreport.

Inaddition,anyregisteredshareholderisentitledtoreceiveacopyoftheunconsolidatedannualaccounts,theconsolidatedaccounts,theauditor'sreportsandthemanagementreportsfreeofchargepriortothedateoftheannualordinarygeneralmeetingofshareholders.

UnderLuxembourglaw,itisgenerallyacceptedthatashareholderhastherighttoreceiveresponsesattheshareholders'generalmeetingtoquestionsconcerningitemsontheagendaofthatgeneralmeetingofshareholders,ifsuchresponsesarenecessaryorusefulforashareholdertomakeaninformeddecisionconcerningsuchagendaitem,unlessaresponsetosuchquestionscouldbedetrimentaltoourinterests.

S-22

Page 26: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Board of Directors

ThemanagementofTrinseoS.A.isvestedinaboardofdirectors(conseil d'administration ).Ourarticlesofassociationprovidethattheboardofdirectorsmustcompriseatleastthreemembersandnomorethantwelvemembers.

TheboardofdirectorsmeetsasoftenasCompanyinterestsrequire.

Amajorityofthemembersoftheboardpresentorrepresentedataboardmeetingconstitutesaquorum,andresolutionsareadoptedbythesimplemajorityvoteoftheboardmemberspresentorrepresented.Theboardmayalsotakedecisionsbymeansofresolutionsinwritingsignedbyalldirectors.Eachdirectorhasonevote.Thegeneralshareholders'meetingelectsdirectorsanddecidestheirrespectiveterms.Pursuanttoourarticlesofassociation,thetermofofficeofthedirectorsis3yearsbuttheymaybere-elected.Thegeneralshareholders'meetingmaydismissoneormoredirectorsatanytime,withorwithoutcausebyanordinaryresolution.Iftheboardhasavacancy,theremainingdirectorsmustfillsuchvacancyonatemporarybasispursuanttotheaffirmativevoteofamajorityoftheremainingdirectors.Thetermofatemporarydirectorelectedtofillavacancyexpiresattheendofthetermofofficeofthereplaceddirector,provided,however,thatthenextgeneralshareholders'meetingshallberequesteddefinitivelytoelectanytemporarydirector.

Withinthelimitsprovidedforbylaw,ourboardmaydelegatetooneormorepersonsthedailymanagementoftheCompanyandtheauthoritytorepresenttheCompany.

Nodirectorshall,solelyasaresultofbeingadirector,bepreventedfromcontractingwithus,eitherwithregardtohistenureinanyofficeorplaceofprofitorasvendor,purchaserorinanyothermannerwhatsoever,norshallanycontractinwhichanydirectorisinanywayinterestedbeliabletobevoidedmerelyonaccountofhispositionasdirector,norshallanydirectorwhoissointerestedbeliabletoaccounttousortheshareholdersforanyremuneration,profitorotherbenefitrealizedbythecontractbyreasonofthedirectorholdingthatofficeorofthefiduciaryrelationshiptherebyestablished.

Anydirectorhavinganinterestinatransactionsubmittedforapprovaltotheboardmayparticipateinthedeliberationsandvotethereon,unlessthetransactionisnotintheordinarycourseoftheCompany'sbusinessandthatconflictswiththeCompany'sinterest,inwhichcasethedirectorshallbeobligedtoadvisetheboardthereofpriortothevoteandtocausearecordofhisstatementtobeincludedintheminutesofthemeeting.Hemaynottakepartinthesedeliberationsnorvoteonsuchatransaction.Atthenextgeneralmeeting,beforeanyotherresolutionisputtoavote,aspecialreportshallbemadeonanytransactionsinwhichanyofthedirectorsmayhavehadaninterestthatconflictswithourinterest.

NoshareholdingqualificationfordirectorsisrequiredunderLuxembourglaw.

Ourarticlesofassociationprovidethatdirectorsandofficers,pastandpresent,areentitledtoindemnificationfromustothefullestextentpermittedbyLuxemburglawagainstliabilityandallexpensesreasonablyincurredorpaidbyhiminconnectionwithanyclaim,action,suitorproceedinginwhichheisinvolvedbyvirtueofhisbeingorhavingbeenadirectororofficerandagainstamountspaidorincurredbyhiminthesettlementthereof.Wemaypurchaseandmaintaininsuranceforanydirectororotherofficeragainstanysuchliability.

Noindemnificationwillbeprovidedagainstanyliabilitytousorourshareholdersbyreasonofwillfulmisfeasance,badfaith,grossnegligenceorrecklessdisregardofthedutiesofadirectororofficeroranymatterastowhichanydirectororofficershallhavebeenfinallyadjudicatedtohaveactedinbadfaithandnotintheinterestoftheCompany.

Transfer Agent and Registrar

ThetransferagentandregistrarforourordinarysharesisAmericanStockTransferandTrustCompany,LLC.

S-23

Page 27: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

MATERIAL UNITED STATES FEDERAL INCOME AND LUXEMBOURG TAX CONSIDERATIONS

United States Federal Income Tax Considerations

Subjecttothelimitationsandqualificationsstatedherein,thisdiscussionsetsforththematerialU.S.federalincometaxconsequencesoftheownershipanddispositionbyU.S.Holders(asdefinedbelow)oftheordinaryshares.ThediscussionisbasedontheU.S.InternalRevenueCodeof1986,asamended,itslegislativehistory,existingandproposedregulationsthereunder,publishedrulingsandcourtdecisions,allascurrentlyineffectandallsubjecttochangeatanytime,possiblywithretroactiveeffect.ThissummaryappliesonlytoU.S.Holdersanddoesnotaddresstaxconsequencestoanon-U.S.Holderinvestinginourordinaryshares.

ThediscussionofaU.S.Holder'staxconsequencesaddressesonlythoseU.S.Holdersthatacquiretheirordinarysharesinthisofferingandthatholdthoseordinarysharesascapitalassetsanddoesnotaddressthetaxconsequencestoanyspecialclassofholders,includingwithoutlimitation,holders(directly,indirectlyorconstructively)of10%ormoreofourshares,dealersinsecuritiesorcurrencies,banks,tax-exemptorganizations,lifeinsurancecompanies,financialinstitutions,broker-dealers,regulatedinvestmentcompanies,realestateinvestmenttrusts,tradersinsecuritiesthatelectthemark-to-marketmethodofaccountingfortheirsecuritiesholdings,personsthatholdsecuritiesthatareahedgeorthatarehedgedagainstcurrencyorinterestraterisksorthatarepartofastraddle,conversionor"integrated"transaction,U.S.expatriates,partnershipsorotherentitiesclassifiedaspartnershipsforU.S.federalincometaxpurposesandU.S.HolderswhosefunctionalcurrencyforU.S.federalincometaxpurposesisnottheU.S.dollar.ThisdiscussiondoesnotaddresstheeffectoftheU.S.federalalternativeminimumtax,orU.S.federalestateandgifttax,oranystate,localorforeigntaxlawsonaholderofordinaryshares.

Forpurposesofthisdiscussion,a"U.S.Holder"isabeneficialownerofordinarysharesthatisforU.S.federalincometaxpurposes:(a)anindividualwhoisacitizenorresidentoftheUnitedStates;(b)acorporation(orotherentitytaxableasacorporationforU.S.federalincometaxpurposes)createdororganizedinorunderthelawsoftheUnitedStates,anystatethereofortheDistrictofColumbia;(c)anestatetheincomeofwhichissubjecttoU.S.federalincometaxationregardlessofitssource;or(d)atrust(i)ifacourtwithintheUnitedStatescanexerciseprimarysupervisionoveritsadministration,andoneormoreU.S.personshavetheauthoritytocontrolallofthesubstantialdecisionsofthattrust,or(ii)thatwasinexistenceonAugust20,1996andvalidlyelectedunderapplicableTreasuryRegulationstocontinuetobetreatedasadomestictrust.Theterm"non-U.S.Holder"meansanybeneficialownerofourordinarysharesthatisnotaU.S.Holder,apartnership(oranentityorarrangementthatistreatedasapartnershipforU.S.federalincometaxpurposes)orapersonholdingourordinarysharesthroughapartnership.

IfapartnershiporanentityorarrangementthatistreatedasapartnershipforU.S.federalincometaxpurposesholdsourordinaryshares,thetaxtreatmentofapartnerwillgenerallydependuponthestatusofthepartnerandtheactivitiesofthepartnership.Partnersinpartnershipsthatholdourordinarysharesshouldconsulttheirowntaxadvisors.

You are Urged to Consult Your Own Independent Tax Advisor Regarding the Specific U.S. Federal, State, Local and Foreign Income and OtherTax Considerations Relating to the Ownership and Disposition of Our Ordinary Shares.

Cash Dividends and Other Distributions

Asdescribedinthesectionentitled"DividendPolicy,"weexpecttomakequarterlycashdistributionstoourshareholdersasrepaymentsofequityordividends,however,anyfuturedeterminationtopaydividendsormakeotherdistributionstoourshareholderswillbeatthediscretionofourboardofdirectors.Totheextentdistributionsaremadewithrespecttoourordinaryshares,

S-24

Page 28: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

subjecttothepassiveforeigninvestmentcompany,or"PFIC,"rulesdiscussedbelow,aU.S.Holderofordinarysharesgenerallywillberequiredtotreatdistributionsreceivedwithrespecttosuchordinaryshares(includinganyamountswithheldpursuanttoLuxembourgtaxlaw)asdividendincometotheextentofourcurrentoraccumulatedearningsandprofits(computedusingU.S.federalincometaxprinciples),withtheexcess(ifany)treatedasanon-taxablereturnofcapitaltotheextentoftheholder'sadjustedtaxbasisintheordinarysharesand,thereafter,ascapitalgain.However,wedonotmaintaincalculationsofourearningsandprofitsinaccordancewithU.S.federalincometaxaccountingprinciples.U.S.Holdersshouldthereforeassumethatdistributionswithrespecttoourordinaryshareswillconstituteordinarydividendincome.DividendspaidontheordinaryshareswillnotbeeligibleforthedividendsreceiveddeductionallowedtoU.S.corporations.

DividendspaidtoanoncorporateU.S.Holderbya"qualifiedforeigncorporation"maybesubjecttoreducedratesoftaxationifcertainholdingperiodandotherrequirementsaremet.Aqualifiedforeigncorporationgenerallyincludesaforeigncorporation(otherthanaPFIC)if(i)itsordinarysharesarereadilytradableonanestablishedsecuritiesmarketintheUnitedStatesor(ii)itiseligibleforbenefitsunderacomprehensiveU.S.incometaxtreatythatincludesanexchangeofinformationprogram.OurordinarysharesarereadilytradableontheNewYorkStockExchange.U.S.InternalRevenueService("IRS")guidanceindicatesthatordinaryshareslistedontheNewYorkStockExchangewillbereadilytradableforpurposesofsatisfyingtheconditionsrequiredforthesereducedtaxrates.U.S.Holdersshouldconsulttheirowntaxadvisorsregardingtheavailabilityofthereducedtaxrateondividendsinlightoftheirparticularcircumstances.

DistributionspaidinacurrencyotherthanU.S.dollarswillbeincludedinaU.S.Holder'sgrossincomeinaU.S.dollaramountbasedonthespotexchangerateineffectonthedateofactualorconstructivereceipt,whetherornotthepaymentisconvertedintoU.S.dollarsatthattime.TheU.S.HolderwillhaveataxbasisinsuchcurrencyequaltosuchU.S.dollaramount,andanygainorlossrecognizeduponasubsequentsaleorconversionoftheforeigncurrencyforadifferentU.S.dollaramountwillbeU.S.sourceordinaryincomeorloss.IfthedividendisconvertedintoU.S.dollarsonthedateofreceipt,aU.S.Holdergenerallyshouldnotberequiredtorecognizeforeigncurrencygainorlossinrespectofthedividendincome.

AU.S.Holderthatpays(whetherdirectlyorthroughwithholding)LuxembourgincometaxwithrespecttodividendspaidonourordinarysharesmaybeentitledtoreceiveeitheradeductionoraforeigntaxcreditforsuchLuxembourgincometaxpaid,ormaybeentitledtoareducedrateofwithholdingundertheapplicableincometaxconventionbetweenLuxembourgandtheUnitedStates,asdescribedbelowunder"LuxembourgTaxConsiderations—WithholdingTaxonDividends."AU.S.HolderthatreceivesdividendsfromwhichLuxembourgincometaxhasbeenwithheldwillberequiredtoincludethegrossamountofthedividendinincome,whichamountmayexceedtheamountofcashreceived.Complexlimitationsapplytotheforeigntaxcredit,includingthegenerallimitationthatthecreditcannotexceedtheproportionateshareofaU.S.Holder'sU.S.federalincometaxliabilitythatsuchU.S.Holder's"foreignsource"taxableincomebearstosuchU.S.Holder'sworldwidetaxableincome.Inapplyingthislimitation,aU.S.Holder'svariousitemsofincomeanddeductionmustbeclassified,undercomplexrules,aseither"foreignsource"or"U.S.source."Inaddition,thislimitationiscalculatedseparatelywithrespecttospecificcategoriesofincome.Dividendspaidbyusgenerallywillconstitute"foreignsource"incomeandgenerallywillbecategorizedas"passivecategoryincome."However,if50%ormoreofourstockistreatedasheldbyU.S.persons,wewillbetreatedasa"UnitedStates—ownedforeigncorporation,"inwhichcasedividendsmaybetreatedforforeigntaxcreditlimitationpurposesas"foreignsource"incometotheextentattributabletoournon-U.S.sourceearningsandprofitsandas"U.S.source"incometotheextentattributabletoourU.S.sourceearningsandprofits.Becausetheforeigntaxcreditrulesarecomplex,eachU.S.Holdershouldconsultitsowntaxadvisorregardingtheforeigntaxcreditrules.

S-25

Page 29: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Sale or Disposition of Ordinary Shares

AU.S.HoldergenerallywillrecognizegainorlossonthetaxablesaleorexchangeoftheordinarysharesinanamountequaltothedifferencebetweentheU.S.dollaramountrealizedonsuchsaleorexchange(determinedinthecaseofsharessoldorexchangedforcurrenciesotherthanU.S.dollarsbyreferencetothespotexchangerateineffectonthedateofthesaleorexchangeor,iftheordinarysharessoldorexchangedaretradedonanestablishedsecuritiesmarketandtheU.S.Holderisacashbasistaxpayeroranelectingaccrualbasistaxpayer,thespotexchangerateineffectonthesettlementdate)andtheU.S.Holder'sadjustedtaxbasisintheordinarysharesdeterminedinU.S.dollars.TheinitialtaxbasisoftheordinarysharestoaU.S.HolderwillbetheU.S.Holder'sU.S.dollarpurchasepricefortheshares(determinedbyreferencetothespotexchangerateineffectonthedateofthepurchase,orifthesharespurchasedaretradedonanestablishedsecuritiesmarketandtheU.S.Holderisacashbasistaxpayeroranelectingaccrualbasistaxpayer,thespotexchangerateineffectonthesettlementdate).

AssumingwearenotaPFICandhavenotbeentreatedasaPFICduringyourholdingperiodforourordinaryshares,suchgainorlosswillbecapitalgainorlossandwillbelong-termgainorlossiftheordinaryshareshavebeenheldformorethanoneyear.Undercurrentlaw,long-termcapitalgainsgenerallyareeligibleforreducedratesoftaxation.Thedeductibilityofcapitallossesissubjecttolimitations.Capitalgainorloss,ifany,recognizedbyaU.S.HoldergenerallywillbetreatedasU.S.sourceincomeorlossforU.S.foreigntaxcreditpurposes.U.S.HoldersareencouragedtoconsulttheirowntaxadvisorsregardingtheavailabilityoftheU.S.foreigntaxcreditintheirparticularcircumstances.

Medicare Contribution Tax

Inadditiontothetaxconsequencesdescribedaboveunder"CashDividendsandOtherDistributions"and"SaleorDispositionofOrdinaryShares,"certainU.S.Holdersthatareindividuals,estatesortrustsaresubjecttoanadditional3.8%Medicarecontributiontaxonthelesserof(1)theU.S.Holder's"netinvestmentincome"fortherelevanttaxableyearand(2)theexcessoftheU.S.Holder'smodifiedadjustedgrossincomeforthetaxableyearoveracertainthreshold.Forthesepurposes,"netinvestmentincome"includes,amongotherthings,dividendson,andcapitalgainsfromthesaleorotherdispositionof,stock.U.S.Holdersareadvisedtoconsulttheirowntaxadvisorsregardingthepossibleimplicationsofthisadditionaltaxinlightoftheirparticularcircumstances.

Potential Application of Passive Foreign Investment Company Provisions

WedonotcurrentlyexpecttobetreatedasaPFICforU.S.federalincometaxpurposeswithrespecttoourtaxableyearendingDecember31,2016,andwedonotexpecttobetreatedasaPFICinthefuture.However,ouractualPFICstatusforanytaxableyearwillnotbedeterminableuntilthecloseofsuchyear,and,accordingly,thereisnoguaranteethatwewillnotbeaPFICforthecurrentoranyfuturetaxableyear.Anon-U.S.corporationisconsideredtobeaPFICforanytaxableyearifeither:

• atleast75%ofitsgrossincomeispassiveincome(the"incometest");or

• atleast50%ofthevalueofitsassets(basedonanaverageofthequarterlyvaluesoftheassetsduringataxableyear)isattributabletoassetsthatproduceorareheldfortheproductionofpassiveincome(the"assettest").

Forpurposesoftheabovetests,wewillbetreatedasowningourproportionateshareoftheassetsandearningourproportionateshareoftheincomeofanyothercorporationinwhichweown,directlyorindirectly,25%ormore(byvalue)ofthecorporation'sstock.Subjecttovariousexceptions,passiveincomegenerallyincludesdividends,interest,rents,royaltiesandgainsfromthedispositionofassetsthatproduceorareheldfortheproductionofpassiveincome.

S-26

Page 30: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

WemustmakeaseparatedeterminationeachyearastowhetherweareaPFIC.ThedeterminationofwhetherweareaPFICismadeannuallyanddependsontheparticularfactsandcircumstances(suchasthevaluationofourassets,includinggoodwillandotherintangibleassets)andalsomaybeaffectedbytheapplicationofthePFICrules,whicharesubjecttodifferinginterpretations.Thefairmarketvalueofourassetsisexpectedtodepend,inpart,upon(a)themarketpriceofourordinaryshares,whichislikelytofluctuate,and(b)thecompositionofourincomeandassets,whichwillbeaffectedbyhow,andhowquickly,wespendanycashthatisraisedinanyfinancingtransaction.Asaresult,ourPFICstatusmaychange.IfweareaPFICforanytaxableyearduringwhichaU.S.Holderholdsordinaryshares,wegenerallywillcontinuetobetreatedasaPFICforallsucceedingyearsduringwhichsuchU.S.Holderholdstheordinaryshares.However,ifweceasetobeaPFIC,aU.S.HoldermayavoidsomeoftheadverseeffectsofthePFICregimethereafterbymakinga"deemedsale"electionwithrespecttotheordinaryshares.

IfweareorbecomeaPFICinataxableyearinwhichwepayadividendorthepriortaxableyear,thereduceddividendratediscussedabovewithrespecttodividendspaidtonon-corporateholderswouldnotapply.Inaddition,ifweareaPFICforanytaxableyearduringwhichaU.S.Holderholdsordinaryshares,theU.S.Holderwillbesubjecttospecialtaxruleswithrespecttoany"excessdistribution"thattheU.S.HolderreceivesandanygaintheU.S.Holderrealizesfromasaleorotherdisposition(includingapledgeoradeemeddisposition)oftheordinaryshares,unlesstheU.S.Holdermakesa"mark-to-market"electionasdiscussedbelow.DistributionstheU.S.Holderreceivesinataxableyearthataregreaterthan125%oftheaverageannualdistributionstheU.S.HolderreceivedduringtheshorterofthethreeprecedingtaxableyearsortheU.S.Holder'sholdingperiodfortheordinaryshareswillbetreatedasexcessdistributions.Underthesespecialtaxrules:

• theexcessdistributionorgainfromasaleorotherdispositionwillbeallocatedratablyovertheU.S.Holder'sholdingperiodfortheordinaryshares;

• theamountallocatedtothecurrenttaxableyear,andanytaxableyearpriortothefirsttaxableyearinwhichtheCompanybecameaPFIC,willbetreatedasordinaryincome;and

• theamountallocatedtoeachotheryearwillbesubjecttothehighestapplicabletaxrateineffectfortheapplicablecategoryoftaxpayerforthattaxableyearandtheinterestchargegenerallyapplicabletounderpaymentsoftaxwillbeimposedontheresultingtaxattributabletoeachsuchyear.AU.S.Holderthatisnotacorporationwillberequiredtotreatanysuchinterestas"personalinterest,"whichisnotdeductible.

Thetaxliabilityforamountsallocatedtoyearspriortotheyearofdispositionor"excessdistribution"cannotbeoffsetbyanynetoperatinglossesforsuchyears,andgains(butnotlosses)realizedonthesaleoftheordinarysharescannotbetreatedascapital,evenifyouholdtheordinarysharesascapitalassets.Specialforeigntaxcreditrulesapplywithrespecttoexcessdistributions.Pleaseconsultyourowntaxadvisorwithrespecttosuchrules.

IfweareaPFICforanytaxableyearduringwhichaU.S.Holderholdsoursharesandanyofournon-U.S.subsidiariesisalsoaPFIC,aU.S.Holderwouldbetreatedasowningaproportionateamount(byvalue)ofthesharesofthelower-tierPFICforpurposesoftheapplicationoftheserules.Underthesecircumstances,aU.S.HolderwouldbesubjecttoU.S.federalincometaxon(i)adistributiononthesharesofalower-tierPFICand(ii)adispositionofsharesofalower-tierPFIC,bothasifsuchU.S.Holderdirectlyheldthesharesofsuchlower-tierPFIC.YouareurgedtoconsultyourowntaxadvisorsabouttheapplicationofthePFICrulestoanyofoursubsidiaries.

Alternatively,incertaincircumstances,aU.S.Holderof"marketablestock"(asdefinedbelow)ofaPFICmaymakeamark-to-marketelectionwithrespecttosuchstocktoelectoutoftheexcessdistributionregimediscussedabove.IfaU.S.Holdermakesavalidmark-to-marketelectionfortheordinarysharestheU.S.Holderwillincludeinincomeeachyearanamountequaltotheexcess,ifany,

S-27

Page 31: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

ofthefairmarketvalueoftheordinarysharesasofthecloseoftheU.S.Holder'staxableyearovertheU.S.Holder'sadjustedbasisinsuchordinaryshares.AU.S.Holderisallowedadeductionfortheexcess,ifany,oftheadjustedbasisoftheordinarysharesovertheirfairmarketvalueasofthecloseofthetaxableyear.However,deductionsareallowableonlytotheextentofanynetmark-to-marketgainsontheordinarysharesincludedinyourincomeforpriortaxableyears.AmountsincludedintheU.S.Holder'sincomeunderamark-to-marketelection,aswellasgainontheactualsaleorotherdispositionoftheordinaryshares,aretreatedasordinaryincome.Ordinarylosstreatmentalsoappliestothedeductibleportionofanymark-to-marketlossontheordinaryshares,aswellastoanylossrealizedontheactualsaleordispositionoftheordinaryshares,totheextentthattheamountofsuchlossdoesnotexceedthenetmark-to-marketgainspreviouslyincludedforsuchordinaryshares.TheU.S.Holder'sbasisintheordinaryshareswillbeadjustedtoreflectanysuchincomeorlossamounts.IfaU.S.Holdermakessuchanelection,thetaxrulesthatapplytodistributionsbycorporationsthatarenotPFICswouldapplytodistributionsbyus,exceptthatthereducedratediscussedaboveunder"—CashDividendsandOtherDistributions"wouldnotapply.IfaU.S.Holdermakesamark-to-marketelection,itwillbeeffectiveforthetaxableyearforwhichtheelectionismadeandallsubsequenttaxableyearsunlesstheordinarysharesarenolonger"marketablestock"(asdefinedbelow)ortheIRSconsentstotherevocationoftheelection.Amark-to-marketelectionwouldnotbeavailablewithrespecttoasubsidiaryPFICofoursthataU.S.HolderisdeemedtoownforthepurposesofthePFICrules;accordingly,aU.S.HolderwouldnotbeabletomitigatecertainoftheadverseU.S."excessdistribution"federalincometaxconsequencesofitsdeemedownershipofstockinoursubsidiaryPFICsbymakingamark-to-marketelection.U.S.Holdersareurgedtoconsulttheirowntaxadvisorsabouttheavailabilityofthemark-to-marketelectionandwhethermakingtheelectionwouldbeadvisableintheirparticularcircumstances.

Asdescribedabove,themark-to-marketelectionisavailableonlyfor"marketablestock,"whichisstockthatistradedinotherthandeminimisquantitiesonatleast15daysduringeachcalendarquarter("regularlytraded")onaqualifiedexchangeorothermarket,asdefinedinapplicableU.S.Treasuryregulations.TheNewYorkStockExchangeisaqualifiedexchange.Pleaseconsultyourowntaxadvisorwithrespecttosuchrules.

U.S.HolderswhoholdordinarysharesinanyyearinwhichweareaPFICwillberequiredtofileIRSForm8621regardinganydistributionsreceivedontheordinarysharesandanygainrealizedonthedispositionofsuchsharesandanannualinformationreturn(alsoonIRSForm8621)relatingtotheirownershipofourordinaryshares.Inaddition,otherreportingrequirementsmayapply.

Incertaincircumstances,holdersofPFICsharescanavoidtherulesdescribedabovebyelectingtotreatthePFICasa"qualifiedelectingfund"underSection1295oftheCode.However,becausewedonotintendtoprepareorprovidetheinformationthatwouldenableaU.S.Holdertomakeaqualifiedelectingfundelection,thisoptionwillnotbeavailabletoU.S.Holders.

YouareurgedtoconsultyourowntaxadvisorregardingtheapplicationofthePFICrulestoyourinvestmentinourordinaryshares.

Reporting Requirements and Backup Withholding

InformationreportingtotheIRSgenerallywillberequiredwithrespecttopaymentsontheordinarysharesandproceedsofthesaleoftheordinarysharespaidwithintheUnitedStatesorthroughcertainU.S.-relatedfinancialintermediariestoholdersthatareU.S.taxpayers,otherthanexemptrecipients.A"backup"withholdingtaxmayapplytothosepaymentsifsuchaholderfailstoprovideataxpayeridentificationnumbertothepayingagentandtocertifythatnolossofexemptionfrombackupwithholdinghasoccurred(orifsuchholderotherwisefailstoestablishanexemption).Weortheapplicablepayingagentwillwithholdonadistributionifrequiredbyapplicablelaw.Theamountswithheldunderthebackupwithholdingrulesarenotanadditionaltaxandmayberefunded,

S-28

Page 32: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

orcreditedagainsttheholder'sU.S.federalincometaxliability,ifany,providedtherequiredinformationistimelyfurnishedtotheIRS.

U.S.Holdersthatowncertain"foreignfinancialassets"(whichmayincludetheordinaryshares)arerequiredtoreportinformationrelatingtosuchassets,subjecttocertainexceptions,onIRSForm8938.Inadditiontotheserequirements,U.S.HoldersmayberequiredtoannuallyfileFinCENReport114,ReportofForeignBankandFinancialAccounts("FBAR")withtheU.S.DepartmentofTreasury.U.S.HoldersshouldconsulttheirowntaxadvisorsregardingtheapplicabilityofFBARandotherreportingrequirementsinlightoftheirindividualcircumstances.

THE ABOVE DISCUSSION DOES NOT COVER ALL TAX MATTERS THAT MAY BE OF IMPORTANCE TO A PARTICULAR INVESTOR.YOU ARE STRONGLY URGED TO CONSULT YOUR OWN TAX ADVISOR ABOUT THE TAX CONSEQUENCES TO YOU OF ANINVESTMENT IN THE ORDINARY SHARES.

Luxembourg Tax Considerations

The following is a general overview of certain important Luxembourg tax consequences that may be or become relevant in relation to a shareholder only andis presented by way of guidance only. It does not purport to be a complete summary of tax law and practice currently applicable in Luxembourg. Any potentialinvestor should consult its own tax advisor for more information about the tax consequences of acquiring, owning and disposing of the shares as it relates to theshareholder's particular circumstances. This taxation overview does not discuss every aspect of taxation that may be relevant to a particular purchaser underspecial circumstances or who is subject to special treatment under applicable law. This overview is based on Luxembourg tax law in force and applied inLuxembourg at the date of this prospectus. The laws upon which this overview is based may change. Any such changes could apply with retroactive effect andcould affect the continued validity of this overview.

Preliminary Consideration on the Luxembourg Tax Residency of the Company's Shareholders

Ashareholderwillnotbecomearesident,norbedeemedtobearesident,ofLuxembourg,bymerelyholdingtheshares,orbytheexecution,performance,deliveryand/orenforcementoftheshares.

Withholding Tax on Dividends

Totheextentthereareanydividendspaidwithrespecttoourordinaryshares,thesedividendsarenormallysubjecttowithholdingtaxinLuxembourgatthedomesticrateof15%,unless(i)thereducedwithholdingtaxratesasprovidedforbyrelevantdoubletaxationtreatiesapplyor,(ii)theconditionstobenefitfromtheexemptionofwithholdingtaxsetoutunderarticle147LuxembourgincometaxlawofDecember4,1967("LITL")aremet:

• onthedatethedistributionismadeavailabletoashareholder,therelevantshareholderholdsorcommitstoholddirectlyorthroughataxtransparentvehicle,duringanuninterruptedperiodofatleast12months,aparticipation(a)representingatleast10%ofthesharecapitaloftheCompany,or(b)havinganacquisitioncostofatleast€1.2million;and

• thebeneficiaryofthedividendsis:

• acompany("société à caractère collectif ")residentinLuxembourgfullyliabletoLuxembourgtax;

• anEUresidentcompanywithinthemeaningofarticle2oftheEUCouncilDirective90/435/ECofJuly23,1990concerningthecommonfiscalregimeapplicabletoparentandsubsidiarycompaniesofdifferentmemberstates("theParent-SubsidiaryDirective",tobereadwiththeCircularL.I.R.No.147/1ofMarch6,2012)oritsLuxembourgpermanentestablishment;or

S-29

Page 33: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

• aSwisscorporationwhichisliabletoSwisscorporatetaxwithoutbenefitingfromanexemption;

• acompanysubjecttoanincometaxationcomparabletotheLuxembourgcorporateincometax(inpracticeataxrateof10.5%appliedonacomparabletaxablebasisshouldbeacceptable),whichisresidentinacountryhavingadoubletaxationtreatywithLuxembourgoritsLuxembourgpermanentestablishment;

• acorporationoracooperativecompanyresidentinanon-EuropeanUnioncountrythatismemberoftheEEAthatisfullysubjecttoanincometaxationcorrespondingtotheLuxembourgcorporateincometax;or

• apermanentestablishmentofacorporationoracooperativecompanyresidentinanon-EuropeanUnioncountrymemberoftheEEA.

Withrespecttotheapplicationofthisexemption,Luxembourgtaxauthoritiestaketheviewthatthewithholdingtaxshouldbeappliedtoanydistributionsmadetoshareholdersholdingadirectparticipationofatleast10%(orhavinganacquisitioncostofatleastof€1.2million)beforethe12monthsperiodhaselapsed.Repaymentofthiswithholdingtaxcanultimatelyberequestedbytherelevantshareholder.

Acommonanti-abuserule(the"CAAR")wasintroducedintheParent-SubsidiaryDirectiveandwasimplementedbytheEUMemberStates,includingLuxembourg,intheirnationallaweffectiveonJanuary1,2016.Underthenewlaw,dividenddistributionsdonotbenefitfromthewithholdingtaxexemptionwhen(i)thebeneficiaryisanEUresidentcompanyorapermanentestablishmentinanotherEUMemberStateofacompanyresidentinaEUMemberStateand(ii)thedistributionsaremadeintheframeworkofanarrangementwhich,havingbeenputinplacewithwhereoneofthemainpurposesisobtainingataxadvantagethatdefeatstheobjectorpurposesoftheParent-SubsidiaryDirective,andisnotgenuineinlightofalltherelevantfactsandcircumstances.Anarrangementwillnotbeconsideredgenuinetotheextentitisnotputinplaceforvalideconomicreasonswhichreflecteconomicreality.

TotheextentawithholdingtaxappliestheCompanyisresponsibleforwithholdingtaxableamounts.

Capital Decrease

Thereimbursementofsharecapital,includingsharepremium,bytheCompanyisnottreatedasadividenddistributionforLuxembourgwithholdingtaxpurposesandthusnotsubjecttoanywithholdingtax,provided(i)therearenoreservesorprofitsattheCompanylevel,and(ii)thecapitaldecreaseismotivatedbysoundbusinessreasons.IncasetheCompanydoesnothavesoundbusinessreasonstoproceedtoacapitaldecrease,theentireamountpaidwillbesubjecttoa15%withholdingtax,unlesstheconditionsforanexemptionorareductionfromthewithholdingtaxondividendssetforthabovearemet.

Arepurchaseofshareswithanimmediatecancellationofthesharesfollowsinprinciplethesametaxtreatmentasareimbursementofsharecapital.However,insuchacase,iftheshareholderceasestobeashareholder,thereimbursementwillnotbesubjecttoawithholdingtax.Incasethesharesarenotimmediatelycancelled,arepurchaseofsharesmaybetreatedforLuxembourgtaxpurposesasadividenddistribution.

S-30

Page 34: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Income Taxation of Luxembourg Resident Shareholders

Luxembourg Resident Individuals

50%ofthedividendsreceivedbyresidentindividuals,whoactinthecourseofeithertheirprivatewealthortheirprofessional/businessactivities,aresubjecttoincometaxattheprogressiveordinaryrate(withthemaximumeffectivemarginaltaxratebeingat42.8%or43.6%dependingontheamountoftaxableincome).Theother50%ofthedividendsreceivedaretax-exempt.The15%withholdingtaxmaybeoffsetagainstthisincometaxliability.

Againrealizeduponthesale,disposalorredemption(however,inthecaseofapartialredemptionthetaxtreatmentappliedwillbethesameasfordividends)ofsharesbyLuxembourgresidentindividualshareholders,actinginthecourseofthemanagementoftheirprivatewealthisnotsubjecttoLuxembourgincometax,providedthissale,disposalorredemptiontookplacemorethan6monthsaftertheshareswereacquiredandprovidedthesharesdonotrepresentasubstantialshareholding.Ashareholdingisconsideredasubstantialshareholdinginlimitedcases,inparticularif(i)therelevantshareholderhasheld,eitheraloneortogetherwithitsspouseorpartnerand/oritsminorchildren,eitherdirectlyorindirectly,atanytimewithinthefiveyearsprecedingtherealizationofthegain,morethan10%ofthesharecapitaloftheCompany,or(ii)thetaxpayeracquiredfreeofcharge,withinthe5yearsprecedingthetransfer,aparticipationthatconstitutedasubstantialparticipationinthehandsofthealienator(orthealienatorsincaseofsuccessivetransfersfreeofchargewithinthesamefive-yearperiod).Capitalgainsrealizedonasubstantialparticipationmorethan6monthsaftertheacquisitionthereofaresubjecttoincometaxaccordingtothehalf-globalratemethod(i.e.,theaveragerateapplicabletothetotalincomeiscalculatedaccordingtoprogressiveincometaxratesandhalfoftheaveragerateisappliedtothecapitalgainsrealizedonthesubstantialparticipation).Adisposalmayincludeasale,anexchange,acontributionoranyotherkindofalienationoftheshareholding.Capitalgainsrealizedonthedisposalofthesharesbyresidentindividualholders,whoactinthecourseoftheirprofessionalorbusinessactivities,aresubjecttoincometaxatordinaryrates.Taxablegainsaredeterminedasbeingthedifferencebetweenthepriceforwhichtheshareshavebeendisposedofandtheloweroftheircostorbookvalue.

50%ofthedividendsreceivedbyresidentindividuals,whoactinthecourseoftheirprofessionalandbusinessactivities,aresubjecttothemunicipalbusinesstax("MBT")ataratedependingonthemunicipalitywhichvariesfrom6%to10.5%.However,forresidentindividuals,MBTisfullytaxdeductible.

Luxembourg Corporate Residents

Luxembourgresidentcorporateshareholders(société à caractère collectif )oftheCompanymustinclude50%ofthedividendsreceivedandanycapitalgainsderivedfromtheshares,intheirtaxableprofitsforLuxembourgincometaxassessmentpurposes(corporateincometax("CIT")andMBTatthemaximumaggregaterateof29.2%in2016forcorporateshareholdershavingtheirstatutoryseatinLuxembourgCity).Theother50%ofthedividendsreceivedaretaxexempt.The15%withholdingtaxmaybeoffsetagainsttheincometaxliability.Taxablegainsaredeterminedasbeingthedifferencebetweenthesale,repurchaseorredemptionpriceandthelowerofthecostorbookvalueofthesharessoldorredeemed.

However,dividendsandliquidationproceedsreceivedbyLuxembourgresidentcorporateshareholdersfromtheCompanywillbeexemptfromCITandMBTincaseofaparticipationhelddirectly,orindirectlythroughataxtransparentvehicle,representingatleast10%ofthesharecapitaloftheCompanyoranacquisitionpriceofatleast€1.2million,providedthatatthetimeoftheincomeismadeavailable,therecipienthasheldorcommitstoholdtheparticipationduringanuninterruptedperiodofatleasttwelvemonths.

S-31

Page 35: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

CapitalgainsrealizedupondisposalofthesharesbyaLuxembourgresidentcorporateshareholderwillbeexemptedincaseofaparticipationhelddirectly,orindirectlythroughataxtransparentvehicle,representingatleast10%ofthesharecapitaloftheCompanyoranacquisitionpriceofatleast€6million,providedthatatthetimeofthedisposal,thebeneficiaryhasheldorcommitstoholdtheparticipationduringanuninterruptedperiodofatleasttwelvemonths.

Luxembourg Residents Benefiting from a Special Tax Regime

LuxembourgresidentshareholdersoftheCompanythatareentitiesbenefitingfromaspecialtaxregime,suchas,(i)undertakingsforcollectiveinvestmentsubjecttotheamendedlawofDecember17,2010(Loi du 17 décembre 2010 concernant les sociétés de placement ),(ii)specializedinvestmentfundssubjecttotheamendedlawofFebruary13,2007(Loi du 13 février 2007 relative aux fonds d'investissement spécialisés ),or(iii)familywealthmanagementcompaniesgovernedbytheamendedlawofMay11,2007(Loi du 11 mai 2007 relative à la création une société de gestion de patrimoine familial (SPF) )aretaxexemptentitiesinLuxembourgandarethusnotsubjecttoanyLuxembourgincometax.

Income Taxation of Luxembourg Non-resident Shareholders

ShareholdersoftheCompanywhoarenon-residentsofLuxembourgandwhohaveneitherapermanentestablishmentnorapermanentrepresentativeinLuxembourgtowhichortowhomthesharesareattributable,aregenerallynotliabletoanyLuxembourgincometax.

Asanexception,anon-residentshareholdermaybeliabletoLuxembourgincometaxoncapitalgainsrealizedonthesharesifithasheld,eitheraloneortogetherwithitsspouseorpartnerand/oritsminorchildren,directlyorindirectly,atanytimewithinthefiveyearsprecedingthedisposaloftheshares,morethan10%ofthesharesoftheCompanyandithaseither(i)heldthesharesforlessthan6months,or(ii)beenaLuxembourgresidenttaxpayerformorethan15yearsandbecameanon-residentlessthanfiveyearsbeforetherealizationofthecapitalgainsontheshares.Dependingontheshareholder'sresidence,suchnon-residentshareholdersmight,however,claimtaxtreatybenefitsinordertoavoidLuxembourgtaxonanysuchcapitalgains.

Non-residentcorporateshareholdersthathaveapermanentestablishmentorapermanentrepresentativeinLuxembourgtowhichorwhomthesharesareattributable,mustincludeanyincomereceived,aswellasanygainrealizedonthesale,disposalorredemptionofshares,intheirtaxableincomeforLuxembourgtaxassessmentpurposes.Thesameinclusionappliestoindividuals,actinginthecourseofthemanagementofaprofessionalorbusinessundertaking,whohaveapermanentestablishmentorapermanentrepresentativeinLuxembourgtowhichorwhomthesharesareattributable.Taxablegainsaredeterminedasbeingthedifferencebetweenthesale,repurchase,orredemptionpriceandthelowerofthecostorbookvalueofthesharessoldorredeemed.

Net Wealth Tax

LuxembourgresidentshareholdersandshareholderswhohaveapermanentestablishmentorapermanentrepresentativeinLuxembourgtowhichorwhomthesharesareattributablearesubjecttoLuxembourgnetwealthtax("NWT")onsuchshares,exceptifsuchshareholderis(i)aresidentornon-residentindividualtaxpayer,(ii)anundertakingforcollectiveinvestmentsubjecttotheamendedlawofDecember17,2010(Loi du 17 décembre 2010 concernant les sociétés deplacement collectif ),(iii)asecuritizationcompanygovernedbytheamendedlawofMarch22,2004onsecuritization(Loi du 22 mars 2004 relative à latitrisation ),(iv)acompanygovernedbytheamendedlawofJune15,2004onventurecapitalvehicles(Loi du 15 juin 2004 relative à la Société d'investissementen capital à risque (SICAR) ),(v)aspecializedinvestmentfundgovernedbytheamendedlawofFebruary13,2007(Loi du 13 février 2007 relative aux fondsd'investissement spécialisés ),(vi)afamilywealthmanagementcompanygovernedbytheamendedlawofMay11,2007(Loi du 11 mai 2007 relative à lacréation d'une

S-32

Page 36: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

société de gestion de patrimoine familial (SPF) ),or(vii)aresidentcorporateshareholderwhoholdsaparticipationdirectly,orindirectlythroughataxtransparentvehicle,representingatleast10%ofthesharecapitaloftheCompanyoranacquisitionpriceofatleast€1.2million.However,iftheshareholderisavehiclelistedaboveunder(iii),(iv)or(vii),asfrom1January2016,itmightbesubject(a)toaminimumnetwealthtaxofEUR3,210,ifitholdsassetssuchasfixedfinancialassets,receivablesowedtoaffiliatedcompanies,transferablesecurities,postalcheckingaccounts,checksandcash,inaproportionthatexceeds90%ofitstotalbalancesheetvalueandifthetotalbalancesheetvalueexceedsEUR350,000or(b)toaminimumnetwealthtaxbetweenEUR535andEUR32,100basedonthetotalamountofitsassets.

Other Taxes

NoLuxembourgvalueaddedtax,Luxembourgregistrationduties,orsimilartaxesareleviedonthetransferoftheshares.

NoestateorinheritancetaxisleviedonthetransferofthesharesupondeathofashareholderoftheCompanyincaseswherethedeceasedwasnotaresidentofLuxembourgforinheritancetaxpurposes.

LuxembourgtaxmaybeleviedonagiftordonationofthesharesifembodiedinaLuxembourgnotarialdeedorotherwiseregisteredinLuxembourg.WhereashareholderisaresidentofLuxembourgfortaxpurposesatthetimeofhisdeath,thesharesareincludedinitstaxableestateforinheritancetaxorestatetaxpurposes.

Foreign Account Tax Compliance Act (FATCA) Requirements

FATCArequiresfinancialinstitutionstoreportonanannualbasistotheIRScertaininformationonU.S.personsthatholdaccountsoutsidetheU.S.,asasafeguardagainstU.S.taxevasion.Inaddition,FATCAgenerallyimposesa30%withholdingtaxoncertainU.S.sourcepayments(includingdividendsandgrossproceedsfromthesaleorotherdisposalofpropertythatcanproduceU.S.sourceincome)whenmadetoanindividualorentitythatdoesnotcomplywithFATCAprovisions.UnderapplicableU.S.TreasuryRegulations,withholdingpursuanttoFATCAwithrespecttogrossproceedswillapplyonlyafterJanuary1,2019.The30%withholdingcouldalsoapplytopaymentsotherwiseattributabletoU.S.sourceincome(alsoknownas"foreignpass-throughpayments").

OnMarch28,2014,theU.S.andtheGrandDuchyofLuxembourgsignedanintergovernmentalagreement(IGA)intheformofModel1,whichrequiresLuxembourgfinancialinstitutionstoreportallFATCA-relatedinformationtotheirowngovernmentalagencies,whichwouldthenreportsuchinformationtotheIRS.TheIGAhasbeenimplementedinLuxembourgbyalawdatedJuly24,2015.

InvestorsshouldconsulttheirowntaxadvisorsregardingtheFATCArequirementswithrespecttotheirownsituationontheirinvestmentintheCompany.Inparticular,investorswhoholdtheirinvestmentthroughintermediariesshouldconfirmtheFATCAcompliancestatusofthoseintermediariestoensurethattheydonotsufferU.S.withholdingtaxontheirinvestmentreturns.

S-33

Page 37: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

SELLING SHAREHOLDER

ThefollowingtablesetsforthinformationregardingthebeneficialownershipofourordinarysharesasofSeptember6,2016,andasadjustedtogiveeffecttotheofferingbythesellingshareholder.

Thepercentageofbeneficialownershipiscalculatedbasedon45,145,431ordinarysharesoutstandingasofSeptember6,2016,excludingtreasuryshares,andthenumberofunissuedsharesastowhichsuchsellingshareholderhastherighttoacquirevotingand/orinvestmentpowerwithin60days.Thebeneficialownershipinformationsetforthbelowwasprovidedbyoronbehalfofthesellingshareholder,andwehavenotindependentlyverifiedtheaccuracyorcompletenessoftheinformationsoprovided.

S-34

Shares Owned Before the Offering

Shares Owned After the Offering

Shares Offered Hereby

Name of Selling Shareholder Number Percentage Number Percentage BainCapitalEverestManagerHoldingSCA(1) 10,669,567 23.6% 10,669,567 — —

(1) ThegeneralpartnerofourParentisBainCapitalEverestManagerS.à.r.l.("BCEM").Byvirtueoftherelationshipsdescribedinthisfootnote,BCEMmaybedeemedtoexercisevotinganddispositivepowerwithrespecttothesharesheldbyParent.MichelG.Plantevin,AurélienVasseur,ChristopherD.Pappas,StephenThomas,FelixHauser,andStephenM.ZideareeachmanagersofBCEM.ThemanagersofBCEMdisclaimbeneficialownershipofsuchsharestotheextentattributedtothemsolelybyvirtueofservingasamanagerofBCEM.AlloftheoutstandingsharecapitalofBCEMisheldbyBainCapitalEuropeFundIII,L.P.("EuropeFundIII")and,inthatcapacity,EuropeFundIIIhasthepowertoappointthemanagersofBCEM.BainCapitalInvestors,LLC("BCI")isthegeneralpartnerofBainCapitalPartnersEuropeIII,L.P.,whichisthegeneralpartnerofEuropeFundIII.Asaresultoftherelationshipsdescribedabove,BCImaybedeemedtosharebeneficialownershipofthesharesheldbyourParent.Thegovernance,investmentstrategyanddecision-makingprocesswithrespecttoinvestmentsheldbyEuropeFundIIIisdirectedbyBCI'sGlobalPrivateEquityBoard("GPEB"),whichiscomprisedofthefollowingindividuals:StevenBarnes,JoshuaBekenstein,JohnConnaughton,DavidGross-Loh,StephenPagliuca,MichelG.Plantevin,DwightPoler,andJonathanZhu.Byvirtueoftherelationshipsdescribedinthisfootnote,GPEBmaybedeemedtoexercisevotinganddispositivepowerwithrespecttothesharesheldbyourParent.EachofthemembersofGPEBdisclaimsbeneficialownershipofsuchsharestotheextentattributedtosuchmembersolelybyvirtueofservingonGPEB.TheaddressforourParentandBCEMis4,rueLouHemmer,L-1748Luxembourg,GrandDuchyofLuxembourg.EuropeFundIIIhasanaddressofUglandHouse,SouthChurchStreet,GeorgeTown,GrandCayman,KY1-1104CaymanIslandsandBCIhasanaddressc/oBainCapitalPrivateEquity,LP,200ClarendonStreet,Boston,Massachusetts02116.TheaddressofMr.Hauserisc/oBainCapitalBeteiligungsberatungGmbHMaximilianstrasse11,80539Munich,Germany.

Page 38: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

UNDERWRITING

MorganStanley&Co.LLCisactingastheunderwriterinconnectionwiththisoffering.SubjecttothetermsandconditionssetforthinanunderwritingagreementamongtheCompany,thesellingshareholderandtheunderwriter,theunderwriterhasagreedtopurchase10,669,567ordinarysharesfromthesellingshareholderatapriceof$pershare,whichwillresultin$ofproceedstothesellingshareholderbeforeexpenses.

Theunderwritermayreceivefrompurchasersofthesharesnormalbrokeragecommissionsinamountsagreedwithsuchpurchasers.TheunderwriterproposestooffertheordinarysharesforsalefromtimetotimeinoneormoretransactionsontheNewYorkStockExchange,intheover-the-countermarket,throughnegotiatedtransactionsorotherwiseatmarketpricesprevailingatthetimeofsale,atpricesrelatedtoprevailingmarketpricesoratnegotiatedprices,subjecttoreceiptandacceptancebytheunderwriterandsubjecttoitsrighttorejectanyorderinwholeorinpart.Theunderwritermayeffectsuchtransactionsbysellingordinarysharestoorthroughdealers,andsuchdealersmayreceivecompensationintheformofdiscounts,concessionsorcommissionsfromtheunderwriterand/orpurchasersofordinarysharesforwhomtheymayactasagentsortowhomtheymaysellasprincipals.Thedifferencebetweenthepriceatwhichtheunderwriterpurchasesordinarysharesandthepriceatwhichtheunderwriterresellssuchordinarysharesmaybedeemedunderwritingcompensation.Theunderwriteriscommittedtotakeandpayforallofthesharesbeingoffered,ifanyaretaken.

Theexpensesoftheofferingareestimatedatapproximately$300,000andarepayablebyus.Thesellingshareholderwillnotpayanyofferingexpenses.WehaveagreedwiththeunderwritertopayactualaccountablelegalfeesandfilingfeesandotherreasonabledisbursementsofcounseltotheunderwriterrelatingtothereviewandqualificationofthisofferingbytheFinancialIndustryRegulatoryAuthority,Inc.inanaggregateamountnottoexceed$30,000.

Inconnectionwiththisoffering,weandeachofourdirectorsandexecutiveofficershaveagreed,subjecttocertainexceptions,that,foraperiodof30daysafterthedateofthisprospectussupplement,weandtheywillnot,withoutthepriorwrittenconsentofMorganStanley&Co.LLC,directlyorindirectlyissue,sell,offer,pledgeorcontracttosell,grantanyoption,rightorwarrantforthesaleof,lendorotherwisetransferordisposeof,anyordinaryshares(otherthanthesharesofferedpursuanttothisoffering)oranysecuritiesconvertibleinto,orexercisableorexchangeablefor,ordinaryshares,includingthefiling(orparticipationinthefiling)ofaregistrationstatementwiththeSECinrespectof,ortheestablishmentorincreaseofaputequivalentpositionortheliquidationordecreaseofacallequivalentpositionwithinthemeaningofSection16oftheExchangeActwithrespectto,anyordinarysharesoranysecuritiesconvertibleinto,orexercisableorexchangeablefor,ordinaryshares;orpubliclyannounceanintentiontoeffectanysuchtransaction.

OurordinarysharesarelistedontheNYSEunderthesymbol"TSE."

Inconnectionwiththeoffering,theunderwritermaypurchaseandsellsharesintheopenmarket.Thesetransactionsmayincludeshortsales,stabilizingtransactionsandpurchasestocoverpositionscreatedbyshortsales.Shortsalesinvolvethesalebytheunderwriterofagreaternumberofsharesthanitisrequiredtopurchaseintheoffering,andashortpositionrepresentstheamountofsuchsalesthathavenotbeencoveredbysubsequentpurchases.Theunderwritermaycoveranycoveredshortpositionbypurchasingsharesintheopenmarket.Stabilizingtransactionsconsistofvariousbidsfororpurchasesofsharesmadebytheunderwriterintheopenmarketpriortothecompletionoftheoffering.

Purchasestocoverashortpositionandstabilizingtransactions,aswellasotherpurchasesbytheunderwriterforitsownaccounts,mayhavetheeffectofpreventingorretardingadeclineinthemarketpriceofthesharesandmaystabilize,togetherwiththeimpositionofthepenaltybid,maintainor

S-35

Page 39: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

otherwiseaffectthemarketpriceoftheshares.Asaresult,thepriceofthesharesmaybehigherthanthepricethatotherwisemightexistintheopenmarket.Theunderwriterisnotrequiredtoengageintheseactivitiesandmayendanyoftheseactivitiesatanytime.ThesetransactionsmaybeeffectedonNYSE,intheover-the-countermarketorotherwise.

Aprospectusinelectronicformatmaybemadeavailableonthewebsitesmaintainedbytheunderwriter.Theunderwritermayagreetoallocateanumberofourordinarysharesforsaletoitsonlinebrokerageaccountholders.TheunderwritermaymakeInternetdistributionsonthesamebasisasotherallocations.Inaddition,ourordinarysharesmaybesoldbytheunderwritertosecuritiesdealerswhoresellsuchsharestoonlinebrokerageaccountholders.Otherthantheprospectusinelectronicformat,theinformationontheunderwriter'sorthesellingshareholder'swebsiteandanyinformationcontainedinanyotherwebsitemaintainedbytheunderwriterisnotpartoftheprospectusortheregistrationstatementofwhichthisprospectussupplementformsapart,hasnotbeenapprovedorendorsedbyusortheunderwriterorthesellingshareholderinitscapacityasunderwriterorthesellingshareholderandshouldnotberelieduponbyinvestors.

Theunderwriteranditsaffiliateshaveengagedin,andmayinthefutureengagein,investmentbankingandothercommercialdealingsintheordinarycourseofbusinesswithusorouraffiliates.Theyhavereceived,ormayinthefuturereceive,customaryfeesandcommissionsforthesetransactions.

Inaddition,intheordinarycourseoftheirbusinessactivities,theunderwriteranditsaffiliatesmaymakeorholdabroadarrayofinvestmentsandactivelytradedebtandequitysecurities(orrelatedderivativesecurities)andfinancialinstruments(includingbankloans)fortheirownaccountandfortheaccountsoftheircustomers.Suchinvestmentsandsecuritiesactivitiesmayinvolvesecuritiesand/orinstrumentsofoursorouraffiliates.Theunderwriteranditsaffiliatesmayalsomakeinvestmentrecommendationsand/orpublishorexpressindependentresearchviewsinrespectofsuchsecuritiesorfinancialinstrumentsandmayhold,orrecommendtoclientsthattheyacquire,longand/orshortpositionsinsuchsecuritiesandinstruments.

OtherthanintheUnitedStates,noactionhasbeentakenbyusortheunderwriterthatwouldpermitapublicofferingoftheordinarysharesofferedbythisprospectussupplementinanyjurisdictionwhereactionforthatpurposeisrequired.Ordinarysharesofferedbythisprospectussupplementmaynotbeofferedorsold,directlyorindirectly,normaythisprospectussupplementoranyotherofferingmaterialoradvertisementsinconnectionwiththeofferandsaleofanysuchordinarysharesbedistributedorpublishedinanyjurisdiction,exceptundercircumstancesthatwillresultincompliancewiththeapplicablerulesandregulationsofthatjurisdiction.Personsintowhosepossessionthisprospectussupplementcomesareadvisedtoinformthemselvesaboutandtoobserveanyrestrictionsrelatingtothisofferingandthedistributionofthisprospectussupplement.Thisprospectussupplementdoesnotconstituteanoffertosellorasolicitationofanoffertobuyanyordinarysharesofferedbythisprospectussupplementinanyjurisdictioninwhichsuchanofferorasolicitationisunlawful.

Canada

Theordinarysharesofferedherebymaybesoldonlytopurchaserspurchasing,ordeemedtobepurchasing,asprincipalthatareaccreditedinvestors,asdefinedinNationalInstrument45-106ProspectusExemptionsorsubsection73.3(1)oftheSecuritiesAct(Ontario),andarepermittedclients,asdefinedinNationalInstrument31-103RegistrationRequirements,ExemptionsandOngoingRegistrantObligations.Anyresaleoftheordinarysharesofferedherebymustbemadeinaccordancewithanexemptionfrom,orinatransactionnotsubjectto,theprospectusrequirementsofapplicablesecuritieslaws.

SecuritieslegislationincertainprovincesorterritoriesofCanadamayprovideapurchaserwithremediesforrescissionordamagesifthisprospectussupplement(includinganyamendmentthereto)containsamisrepresentation,providedthattheremediesforrescissionordamagesareexercisedbythe

S-36

Page 40: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

purchaserwithinthetimelimitprescribedbythesecuritieslegislationofthepurchaser'sprovinceorterritory.Thepurchasershouldrefertoanyapplicableprovisionsofthesecuritieslegislationofthepurchaser'sprovinceorterritoryforparticularsoftheserightsorconsultwithalegaladvisor.

Pursuanttosection3A.3ofNationalInstrument33-105UnderwritingConflicts(NI33-105),theunderwriterisnotrequiredtocomplywiththedisclosurerequirementsofNI33-105regardingunderwriterconflictsofinterestinconnectionwiththisoffering.

European Economic Area

InrelationtoeachMemberStateoftheEuropeanEconomicAreawhichhasimplementedtheProspectusDirective(each,a"RelevantMemberState"),theunderwriterhasrepresentedandagreedthatwitheffectfromandincludingthedateonwhichtheProspectusDirectiveisimplementedinthatRelevantMemberState(the"RelevantImplementationDate")ithasnotmadeandwillnotmakeanofferofsharestothepublicinthatRelevantMemberStatepriortothepublicationofaprospectusinrelationtotheshareswhichhasbeenapprovedbythecompetentauthorityinthatRelevantMemberStateor,whereappropriate,approvedinanotherRelevantMemberStateandnotifiedtothecompetentauthorityinthatRelevantMemberState,allinaccordancewiththeProspectusDirective,exceptthatitmay,witheffectfromandincludingtheRelevantImplementationDate,makeanofferofsharestothepublicinthatRelevantMemberStateatanytime:

(a)toanylegalentitywhichisaqualifiedinvestorasdefinedintheProspectusDirective;

(b)tofewerthan100or,iftheRelevantMemberStatehasimplementedtherelevantprovisionofthe2010PDAmendingDirective,150naturalorlegalpersons(otherthanqualifiedinvestors,asdefinedintheProspectusDirective)subjecttoobtainingthepriorconsentoftherepresentativesforanysuchoffer;or

(c)inanyothercircumstanceswhichdonotrequirethepublicationbyusofaprospectuspursuanttoArticle3oftheProspectusDirective.

Forthepurposesofthisprovision,theexpressionan"offerofsharestothepublic"inrelationtoanysharesinanyRelevantMemberStatemeansthecommunicationinanyformandbyanymeansofsufficientinformationonthetermsfortheofferandthesharestobeofferedsoastoenableaninvestortodecidetopurchaseorsubscribetheshares,asthesamemaybevariedinthatRelevantMemberStatebyanymeasureimplementingtheProspectusDirectiveinthatRelevantMemberState,theexpressionProspectusDirectivemeansDirective2003/71/EC(andamendmentsthereto,includingthePD2010AmendingDirectivetotheextentimplementedintheRelevantMemberState)andincludesanyrelevantimplementingmeasureineachRelevantMemberState,andtheexpression2010PDAmendingDirectivemeansDirective2010/73/EU.

United Kingdom

Thisprospectusandanyothermaterialinrelationtothesharesdescribedhereinisonlybeingdistributedto,andisonlydirectedat,personsintheUnitedKingdomthatarequalifiedinvestorswithinthemeaningofArticle2(1)(e)oftheProspectiveDirective("qualifiedinvestors")thatalso(i)haveprofessionalexperienceinmattersrelatingtoinvestmentsfallingwithinArticle19(5)oftheFinancialServicesandMarketsAct2000(FinancialPromotion)Order2005,asamended,ortheOrder,(ii)whofallwithinArticle49(2)(a)to(d)oftheOrderor(iii)towhomitmayotherwiselawfullybecommunicated(allsuchpersonstogetherbeingreferredtoas"relevantpersons").Thesharesareonlyavailableto,andanyinvitation,offeroragreementtopurchaseorotherwiseacquiresuchshareswillbeengagedinonlywith,relevantpersons.Thisprospectusanditscontentsareconfidentialandshouldnotbedistributed,publishedorreproduced(inwholeorinpart)ordisclosedbyrecipientstoanyother

S-37

Page 41: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

personintheUnitedKingdom.AnypersonintheUnitedKingdomthatisnotarelevantpersonshouldnotactorrelyonthisprospectusoranyofitscontents.

Switzerland

ThesharesmaynotbepubliclyofferedinSwitzerlandandwillnotbelistedontheSIXSwissExchange(the"SIX")oronanyotherstockexchangeorregulatedtradingfacilityinSwitzerland.Thisdocumenthasbeenpreparedwithoutregardtothedisclosurestandardsforissuanceprospectusesunderart.652aorart.1156oftheSwissCodeofObligationsorthedisclosurestandardsforlistingprospectusesunderart.27ff.oftheSIXListingRulesorthelistingrulesofanyotherstockexchangeorregulatedtradingfacilityinSwitzerland.NeitherthisdocumentnoranyotherofferingormarketingmaterialrelatingtothesharesortheofferingmaybepubliclydistributedorotherwisemadepubliclyavailableinSwitzerland.

Neitherthisprospectusnoranyotherofferingormarketingmaterialrelatingtotheoffering,theissuer,ortheshareshavebeenorwillbefiledwithorapprovedbyanySwissregulatoryauthority.Inparticular,thisprospectuswillnotbefiledwith,andtheofferofshareswillnotbesupervisedby,theSwissFinancialMarketSupervisoryAuthorityFINMA(the"FINMA"),andtheofferofshareshasnotbeenandwillnotbeauthorizedundertheSwissFederalActonCollectiveInvestmentSchemes(the"CISA").TheinvestorprotectionaffordedtoacquirersofinterestsincollectiveinvestmentschemesundertheCISAdoesnotextendtoacquirersofshares.

The Dubai International Financial Center

ThisprospectusrelatestoanExemptOfferinaccordancewiththeOfferedSecuritiesRulesoftheDubaiFinancialServicesAuthority(the"DFSA").ThisprospectusisintendedfordistributiononlytopersonsofatypespecifiedintheOfferedSecuritiesRulesoftheDFSA.Itmustnotbedeliveredto,orreliedonby,anyotherperson.TheDFSAhasnoresponsibilityforreviewingorverifyinganydocumentsinconnectionwithExemptOffers.TheDFSAhasnotapprovedthisprospectusnortakenstepstoverifytheinformationsetforthhereinandhasnoresponsibilityforthisprospectus.Thesharestowhichthisprospectusrelatesmaybeilliquidand/orsubjecttorestrictionsontheirresale.Prospectivepurchasersofthesharesofferedshouldconducttheirownduediligenceontheshares.Ifyoudonotunderstandthecontentsofthisprospectusyoushouldconsultanauthorizedfinancialadvisor.

Hong Kong

Thesharesmaynotbeofferedorsoldbymeansofanydocumentotherthan(i)incircumstanceswhichdonotconstituteanoffertothepublicwithinthemeaningoftheCompaniesOrdinance(Cap.32,LawsofHongKong),or(ii)to"professionalinvestors"withinthemeaningoftheSecuritiesandFuturesOrdinance(Cap.571,LawsofHongKong)andanyrulesmadethereunder,or(iii)inothercircumstanceswhichdonotresultinthedocumentbeinga"prospectus"withinthemeaningoftheCompaniesOrdinance(Cap.32,LawsofHongKong),andnoadvertisement,invitationordocumentrelatingtothesharesmaybeissuedormaybeinthepossessionofanypersonforthepurposeofissue(ineachcasewhetherinHongKongorelsewhere),whichisdirectedat,orthecontentsofwhicharelikelytobeaccessedorreadby,thepublicinHongKong(exceptifpermittedtodosounderthelawsofHongKong)otherthanwithrespecttoshareswhichareorareintendedtobedisposedofonlytopersonsoutsideHongKongoronlyto"professionalinvestors"withinthemeaningoftheSecuritiesandFuturesOrdinance(Cap.571,LawsofHongKong)andanyrulesmadethereunder.

S-38

Page 42: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Singapore

ThisprospectushasnotbeenregisteredasaprospectuswiththeMonetaryAuthorityofSingapore.Accordingly,thisprospectusandanyotherdocumentormaterialinconnectionwiththeofferorsale,orinvitationforsubscriptionorpurchase,ofthesharesmaynotbecirculatedordistributed,normaythesharesbeofferedorsold,orbemadethesubjectofaninvitationforsubscriptionorpurchase,whetherdirectlyorindirectly,topersonsinSingaporeotherthan(i)toaninstitutionalinvestorunderSection274oftheSecuritiesandFuturesAct,Chapter289ofSingapore(the"SFA"),(ii)toarelevantperson,oranypersonpursuanttoSection275(1A),andinaccordancewiththeconditions,specifiedinSection275oftheSFAor(iii)otherwisepursuantto,andinaccordancewiththeconditionsof,anyotherapplicableprovisionoftheSFA.

WherethesharesaresubscribedorpurchasedunderSection275byarelevantpersonwhichis:(a)acorporation(whichisnotanaccreditedinvestor)thesolebusinessofwhichistoholdinvestmentsandtheentiresharecapitalofwhichisownedbyoneormoreindividuals,eachofwhomisanaccreditedinvestor;or(b)atrust(wherethetrusteeisnotanaccreditedinvestor)whosesolepurposeistoholdinvestmentsandeachbeneficiaryisanaccreditedinvestor,shares,debenturesandunitsofsharesanddebenturesofthatcorporationorthebeneficiaries'rightsandinterestinthattrustshallnotbetransferableforsixmonthsafterthatcorporationorthattrusthasacquiredthesharesunderSection275except:(1)toaninstitutionalinvestorunderSection274oftheSFAortoarelevantperson,oranypersonpursuanttoSection275(1A),andinaccordancewiththeconditions,specifiedinSection275oftheSFA;(2)wherenoconsiderationisgivenforthetransfer;or(3)byoperationoflaw.

S-39

Page 43: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

LEGAL MATTERS

CertainlegalmattersinconnectionwiththisofferingwillbepasseduponforusbyRopes&GrayLLP,Boston,Massachusetts.Ropes&GrayLLPandsomeofitsattorneysarelimitedpartnersofRGIP,LP,whichisaninvestorincertaininvestmentfundsadvisedormanagedbyBainCapitalPrivateEquity,LPandoftenaco-investorwithsuchfunds.RGIP,LPindirectlyownslessthan1%ofouroutstandingordinaryshares.ThevalidityoftheissuanceofordinarysharestobesoldinthisofferingwillbepasseduponforusbyLoyens&LoeffLuxembourgS.à.r.l.,Luxembourg.CahillGordon&ReindelLLP,NewYork,NewYorkisactingascounseltotheunderwriter.

EXPERTS

TheauditedfinancialstatementsofTrinseoS.A.incorporatedinthisprospectussupplementbyreferencetotheAnnualReportonForm10-KfortheyearendedDecember31,2015,exceptastheyrelatetoAmericasStyrenicsLLC,andtheeffectivenessofinternalcontroloverfinancialreportingasofDecember31,2015havebeenauditedbyPricewaterhouseCoopersLLP,anindependentregisteredpublicaccountingfirm.Suchfinancialstatements,exceptastheyrelatetoAmericasStyrenicsLLC,andmanagement'sassessmentoftheeffectivenessofinternalcontroloverfinancialreportinghavebeensoincorporatedinrelianceonthereportofsuchindependentregisteredpublicaccountingfirmgivenontheauthorityofsaidfirmasexpertsinauditingandaccounting.

TheconsolidatedfinancialstatementsofAmericasStyrenicsLLC,incorporatedinthisprospectussupplementbyreferencefromTrinseoS.A.'sAnnualReportonForm10-KfortheyearendedDecember31,2015,havebeenauditedbyDeloitte&ToucheLLP,anindependentregisteredpublicaccountingfirm,asstatedintheirreport,whichisincorporatedhereinbyreference.Suchfinancialstatementshavebeensoincorporatedinrelianceuponthereportofsuchfirmgivenupontheirauthorityasexpertsinaccountingandauditing.

WHERE YOU CAN FIND MORE INFORMATION

WehavefiledwiththeSECaregistrationstatementonFormS-3undertheSecuritiesActwithrespectourordinarysharesbeingofferedbythisprospectussupplementandtheaccompanyingprospectus.Thisprospectussupplementandtheaccompanyingprospectusdonotcontainalloftheinformationsetforthintheregistrationstatement.Forfurtherinformationwithrespecttousandtheordinaryshares,referenceismadetotheregistrationstatementanditsexhibits.Statementscontainedinthisprospectussupplementortheaccompanyingprospectusastothecontentsofanycontractorotherdocumentarenotnecessarilycomplete.Wearerequiredtofileannualandquarterlyreports,specialreports,proxystatements,andotherinformationwiththeSEC.Theregistrationstatement,suchreportsandotherinformationcanbeinspectedandcopiedatthePublicReferenceRoomoftheSEClocatedat100FStreet,N.E.,Washington,D.C.20549.Copiesofsuchmaterials,includingcopiesofalloranyportionoftheregistrationstatement,canbeobtainedfromthePublicReferenceRoomoftheSECatprescribedrates.YoucancalltheSECat1-800-SEC-0330toobtaininformationontheoperationofthePublicReferenceRoom.SuchmaterialsmayalsobeaccessedelectronicallybymeansoftheSEC'swebsiteatwww.sec.gov.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

TheSECallowsusto"incorporatebyreference"intothisprospectussupplementandtheaccompanyingprospectusinformationwefilewithit,whichmeansthatwecandiscloseimportantinformationtoyoubyreferringyoutothosedocuments.Theinformationincorporatedbyreferenceisconsideredtobepartofthisprospectussupplementandtheaccompanyingprospectus,andinformationindocumentsthatwefilelaterwiththeSECwillautomaticallyupdateandsupersedeinformationinthisprospectussupplement.Weincorporatebyreferenceintothisprospectussupplementandthe

S-40

Page 44: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

accompanyingprospectusthedocumentslistedbelowandanyfuturefilingsmadebyuswiththeSECunderSection13(a),13(c),14or15(d)oftheExchangeAct,except,ineachcase,forinformation"furnished"underItems2.02,7.01or9.01onForm8-Korotherinformation"furnished"totheSECwhichisnotdeemedfiledandnotincorporatedinthisprospectussupplementortheaccompanyingprospectus,untiltheterminationofthisoffering.Weherebyincorporatebyreferencethefollowingdocuments:

• OurannualreportonForm10-KfortheyearendedDecember31,2015,filedwiththeSEConMarch11,2016(FileNo.001-36473),andasamendedonMarch15,2016;

• OurquarterlyreportsonForm10-QforthequartersendedMarch31,2016andJune30,2016,filedwiththeSEConMay5,2016andAugust3,2016,respectively(FileNo.001-36473);

• OurcurrentreportsonForm8-KfiledwiththeSEConJanuary26,2016,February26,2016,March24,2016,April5,2016,May11,2016,May23,2016,June22,2016,July27,2016,August12,2016,August16,2016,August30,2016andAugust31,2016(FileNo.001-36473);and

• ThedescriptionofourordinarysharescontainedintheRegistrationStatementonForm8-A,asfiledwiththeSEConJune2,2014(FileNo.001-36473).

Youmayrequestacopyofthesefilings,atnocost,bywritingortelephoningusatthefollowingaddress:

TrinseoS.A.Attn:CorporateSecretary

1000ChesterbrookBoulevardSuite300

Berwyn,PA19312(610)240-3200

Copiesofthesefilingsarealsoavailable,withoutcharge,ontheSEC'swebsiteatwww.sec.govandonourwebsite,www.trinseo.com,assoonasreasonablypracticableaftertheyarefiledelectronicallywiththeSEC.Theinformationcontainedonourwebsiteisnotapartofthisprospectussupplementortheaccompanyingprospectus.

S-41

Page 45: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

Trinseo S.A.37,269,567 Ordinary Shares

Thesellingshareholderidentifiedinthisprospectusmayofferandsellfromtimetotime,inoneormoreseriesorissuancesandontermsthatwillbedeterminedatthetimeoftheoffering,37,269,567ordinarysharesofTrinseoS.A.Wewillnotreceiveanyproceedsfromthesaleofsharesbythesellingshareholder.

Wewillprovidespecifictermsofanyofferinginasupplementtothisprospectus.Anyprospectussupplementmayalsoadd,update,orchangeinformationcontainedinthisprospectus.Youshouldcarefullyreadthisprospectusandtheapplicableprospectussupplementaswellasthedocumentsincorporatedordeemedtobeincorporatedbyreferenceinthisprospectusandtheapplicableprospectussupplementbeforeyoupurchaseanyofthesecuritiesofferedhereby.

OurordinarysharesarelistedontheNewYorkStockExchangeunderthesymbol"TSE."OnMarch14,2016,thelastsalepriceofourordinarysharesasreportedontheNewYorkStockExchangewas$34.67pershare.

Investing in our ordinary shares involves substantial risks. See "Risk Factors" beginning on page 3 of this prospectus toread about factors you should consider before buying our ordinary shares.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed onthe accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

ProspectusdatedMarch15,2016

Page 46: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TABLE OF CONTENTS

Wehavenotauthorizedanyonetoprovideanyinformationortomakeanyrepresentationsotherthanthosecontainedorincorporatedbyreferenceinthisprospectus,anyaccompanyingprospectussupplementorinanyfreewritingprospectuseswehaveprepared.Wetakenoresponsibilityfor,andcanprovidenoassuranceastothereliabilityof,anyotherinformationthatothersmaygiveyou.Thisprospectusandanyaccompanyingprospectussupplementareanoffertosellonlythesharesofferedhereby,butonlyundercircumstancesandinjurisdictionswhereitislawfultodoso.Theinformationcontainedorincorporatedbyreferenceinthisprospectusandanyaccompanyingprospectussupplementiscurrentonlyasofthedateoftheapplicabledocument.

AboutthisProspectus 1AboutTrinseoS.A. 2RiskFactors 3CautionaryNoteRegardingForward-LookingStatements 4UseofProceeds 6SellingShareholder 6PlanofDistribution 7LegalMatters 9Experts 9WhereYouCanFindMoreInformation 9IncorporationofCertainInformationbyReference 9

Page 47: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

ABOUT THIS PROSPECTUS

ThisprospectusispartofaregistrationstatementonFormS-3thatwefiledwiththeSecuritiesandExchangeCommission(the"SEC")undertheSecuritiesActof1933,asamended("SecuritiesAct"),usinga"shelf"registrationprocess.Underthisshelfregistrationprocess,thesellingshareholdermay,onacontinuousbasis,inoneormoreofferings,sellorotherwisedisposeofupto37,269,567ordinaryshares.Thisprospectusincorporatesbyreferenceimportantbusinessandfinancialinformationaboutusthatisnotincludedinordeliveredwiththisdocument.Youshouldreadtheadditionalinformationdescribedunder"WhereYouCanFindMoreInformation"and"IncorporationofCertainInformationbyReference."

Wewillnotreceiveanyproceedsfromthesaleorotherdispositionoftheordinarysharesregisteredhereunder.

Wehavenotauthorizedanydealer,agentorotherpersontogiveanyinformationortomakeanyrepresentationotherthanthosecontainedorincorporatedbyreferenceinthisprospectus.Thisprospectusdoesnotconstituteanoffertosellorthesolicitationofanoffertobuyanysecuritiesotherthantheregisteredsecuritiestowhichtheyrelate,nordoesthisprospectusconstituteanoffertosellorthesolicitationofanoffertobuysecuritiesinanyjurisdictiontoanypersontowhomitisunlawfultomakesuchofferorsolicitationinsuchjurisdiction.Youshouldnotassumethattheinformationcontainedinthisprospectusisaccurateonanydatesubsequenttothedatesetforthonthefrontofthedocumentorthatanyinformationwehaveincorporatedbyreferenceiscorrectonanydatesubsequenttothedateofthedocumentincorporatedbyreference,eventhoughthisprospectusandanyaccompanyingprospectussupplementisdeliveredorsecuritiesaresoldonalaterdate.

Unlessotherwiseindicatedorthecontextotherwiserequires,theterms"Trinseo,""we,""us,""our,""ourCompany"and"ourbusiness"refertoTrinseoS.A.togetherwithitsconsolidatedsubsidiaries.Priortoourformation,ourbusinesseswerewholly-ownedbyTheDowChemicalCompany.Werefertoourpredecessorbusinessesas"theStyronbusiness."OnJune17,2010,investmentfundsadvisedormanagedbyBainCapitalPartners,LPacquiredtheStyronbusiness,andDowEuropeHoldingB.V.,whichwerefertoas"DowEurope,"or,togetherwithotheraffiliatesofTheDowChemicalCompany,"Dow,"retainedanownershipinterestintheStyronbusinessthroughanindirectownershipinterestinus.Werefertothistransactionasthe"Acquisition."Referencesto"sellingshareholder"and"Parent"refertoBainCapitalEverestManagerHoldingsSCAdescribedundertheheading"SellingShareholder"onpage6,whomaysellsharesasdescribedinthisprospectus.

Youshouldcarefullyreadtheentireprospectus,includinginformationincorporatedbyreferenceintothisprospectusandthe"RiskFactors"and"CautionaryNoteRegardingForward-LookingStatements"sectionsofthisprospectus,beforedecidingwhethertoinvestinourordinaryshares.

1

Page 48: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

ABOUT TRINSEO S.A.

Trinseoisaleadingglobalmaterialscompanyengagedinthemanufactureandmarketingofsyntheticrubber,latex,andplastics,includingvariousspecialtyandtechnologicallydifferentiatedproducts.Trinseo'sproductsareincorporatedintoawiderangeofproductsthroughouttheworld,includingtiresandotherproductsforautomotiveapplications,carpetandartificialturfbacking,coatedpaperandpackagingboard,foodpackaging,appliances,medicaldevices,consumerelectronicsandconstructionapplications.Trinseohadapproximately$4.0billioninnetsalesin2015,andasofDecember31,2015had2,270employeesand18manufacturingsitesworldwide.

TrinseoisaLuxembourglimitedliabilitycompany(société anonyme ),witharegisteredofficeat4,rueLouHemmer,L-1748Luxembourg,GrandDuchyofLuxembourgandregisteredwithLuxembourg'sRegisterofCommerceandCompanies(RCS)underRCSnumberB153.549.

2

Page 49: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

RISK FACTORS

Investing in our ordinary shares involves a high degree of risk. See "Item 1A. Risk Factors" in our most recent Annual Report on Form 10-K incorporated byreference in this prospectus and in any subsequent Quarterly Report on Form 10-Q and the "Risk Factors" section in the applicable prospectus supplement for adiscussion of the factors you should carefully consider before deciding to purchase our ordinary shares.

3

Page 50: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

Thisprospectus,includinginformationincorporatedbyreferenceherein,containsforward-lookingstatementsincluding,withoutlimitation,statementsconcerningplans,objectives,goals,projections,strategies,futureeventsorperformance,andunderlyingassumptionsandotherstatements,whicharenotstatementsofhistoricalfacts.Forward-lookingstatementsmaybeidentifiedbytheuseofwordslike"expect,""anticipate,""intend,""forecast,""outlook,""will,""may,""might,""potential,""likely,""target,""plan,""contemplate,""seek,""attempt,""should,""could,""would"orexpressionsofsimilarmeaning.Forward-lookingstatementsreflectmanagement'sevaluationofinformationcurrentlyavailableandarebasedonourcurrentexpectationsandassumptionsregardingourbusiness,theeconomyandotherfutureconditions.Becauseforward-lookingstatementsrelatetothefuture,theyaresubjecttoinherentuncertainties,risksandchangesincircumstancesthataredifficulttopredict.Specificfactorsthatmayimpactperformanceorotherpredictionsoffutureactionshave,inmanybutnotallcases,beenidentifiedinconnectionwithspecificforward-lookingstatements.Ouractualresultsmaydiffermateriallyfromthosecontemplatedbytheforward-lookingstatements.Theyareneitherstatementsofhistoricalfactnorguaranteesorassurancesoffutureperformance.Importantfactorsthatcouldcauseactualresultstodiffermateriallyfromthoseintheforward-lookingstatementsincludeeconomic,business,competitive,marketandregulatoryconditionsandthefollowing:

• ourcurrentlevelofindebtedness;

• thestabilityofourjointventures;

• lawsuitsresultingfromproductsoroperations;

• volatilityincostsordisruptioninthesupplyoftherawmaterialsutilizedforourproducts;

• hazardsassociatedwithchemicalmanufacturing;

• thecompetitivenatureofourendmarkets;

• ourcontinuedrelianceonourrelationshipwithTheDowChemicalCompany;

• ourcompliancewithenvironmental,healthandsafetylaws;

• conditionsintheglobaleconomyandcapitalmarkets;

• anydisruptionsinproductionatourmanufacturingfacilities;

• increasesinthecostofenergy;

• ourabilitytomaintainthenecessarylicensesandpermitsweneedforouroperations;

• failuretomaintainaneffectivesystemofinternalcontrols;

• currentinsurancenotcoveringallpotentialexposures;

• changesinlawsandregulationsapplicabletoourbusiness;

• ourdependenceuponkeyexecutivemanagementandanyinabilitytoattractandretainotherqualifiedmanagementpersonnel;

• fluctuationsincurrencyexchangerates;

• strategicacquisitionsaffectingcurrentoperations;

• thelossofcustomers;

• anyinabilitytocontinuetechnologicalinnovationandsuccessfulintroductionofnewproducts;

• anyinabilitytoprotectourtrademarks,patentsorotherintellectualpropertyrights;

4

Page 51: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

• datasecuritybreaches;

• failureofourassumptionsandprojectionstobeaccurate;

• localbusinessrisksindifferentcountriesinwhichweoperate;

• seasonalityofourbusiness;and

• otherrisksdescribedinthe"RiskFactors"sectionofthisprospectusandtheapplicableprospectussupplement.

Wederivemanyofourforward-lookingstatementsfromouroperatingbudgetsandforecasts,whicharebaseduponmanydetailedassumptions.Whilewebelievethatourassumptionsarereasonable,wecautionthatitisverydifficulttopredicttheimpactofknownfactors,anditisimpossibleforustoanticipateallfactorsthatcouldaffectouractualresults.Importantfactorsthatcouldcauseactualresultstodiffermateriallyfromourexpectations,orcautionarystatements,aredisclosedunderthesectionentitled"RiskFactors"andthesectionsentitled"Management'sDiscussionandAnalysisofFinancialConditionandResultsofOperations"fromourAnnualReportonForm10-KandQuarterlyReportsonForm10-Q,incorporatedbyreferenceintothisprospectus.Allwrittenandoralforward-lookingstatementsattributabletous,orpersonsactingonourbehalf,areexpresslyqualifiedintheirentiretybythecautionarystatementsaswellasothercautionarystatementsthataremadefromtimetotimeinourotherpubliccommunications.Youshouldevaluateallforward-lookingstatementsmadeinthisprospectusandthedocumentsincorporatedbyreferencehereininthecontextoftheserisksanduncertainties.

Wecautionyouthattheimportantfactorsreferencedabovemaynotcontainallofthefactorsthatareimportanttoyou.Inaddition,wecannotassureyouthatwewillrealizetheresultsordevelopmentsweexpectoranticipateor,evenifsubstantiallyrealized,thattheywillresultintheconsequencesoraffectusorouroperationsinthewayweexpect.Theforward-lookingstatementsincludedinthisprospectusandthedocumentsincorporatedbyreferencehereinaremadeonlyasofthedateoftheapplicabledocument.Weundertakenoobligationtopubliclyupdateorreviseanyforward-lookingstatementasaresultofnewinformation,futureeventsorotherwise,exceptasotherwiserequiredbylaw.

5

Page 52: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

USE OF PROCEEDS

Wewillnotreceiveanyproceedsfromthesaleofourordinarysharesbythesellingshareholder.

SELLING SHAREHOLDER

Thesellingshareholdernamedinthisprospectusmayoffertosellfromtimetotimeupto37,269,567ofourordinaryshares,asprovidedinthisprospectusunderthesectionentitled"PlanofDistribution"andinanyapplicableprospectussupplement.However,wedonotknowwhenorinwhatamountthesellingshareholdermayofferitssharesforsaleunderthisprospectus.ThesellingshareholderreceivedsuchsharesinconnectionwiththeAcquisition.

6

Maximum Number of Shares that

may be offered

pursuant to this

Prospectus

Shares owned Prior to the

Offering Shares Owned After the

Offering

Name Number of

Shares Percentage Number of

Shares Percentage BainCapitalEverestManagerHoldingsSCA("Parent")(1) 37,269,567 76.4% 37,269,567

(1) ThegeneralpartnerofourParentisBainCapitalEverestManagerS.à.r.l.("BCEM").Byvirtueoftherelationshipsdescribedinthisfootnote,BCEMmaybedeemedtoexercisevotinganddispositivepowerwithrespecttothesharesheldbyParent.MichelG.Plantevin,AurélienVasseur,ChristopherD.Pappas,StephenThomas,FelixHauser,andStephenM.ZideareeachmanagersofBCEM.ThemanagersofBCEMdisclaimbeneficialownershipofsuchsharestotheextentattributedtothemsolelybyvirtueofservingasamanagerofBCEM.AlloftheoutstandingsharecapitalofBCEMisheldbyBainCapitalEuropeFundIII,L.P.("EuropeFundIII")and,inthatcapacity,EuropeFundIIIhasthepowertoappointthemanagersofBCEM.BainCapitalInvestors,LLC("BCI")isthegeneralpartnerofBainCapitalPartnersEuropeIII,L.P.,whichisthegeneralpartnerofEuropeFundIII.Asaresultoftherelationshipsdescribedabove,BCImaybedeemedtosharebeneficialownershipofthesharesheldbyourParent.Thegovernance,investmentstrategyanddecision-makingprocesswithrespecttoinvestmentsheldbyEuropeFundIIIisdirectedbyBCI'sGlobalPrivateEquityBoard("GPEB"),whichiscomprisedofthefollowingindividuals:StevenBarnes,JoshuaBekenstein,JohnConnaughton,DavidGross-Loh,StephenPagliuca,MichelG.Plantevin,DwightPoler,andJonathanZhu.Byvirtueoftherelationshipsdescribedinthisfootnote,GPEBmaybedeemedtoexercisevotinganddispositivepowerwithrespecttothesharesheldbyourParent.EachofthemembersofGPEBdisclaimsbeneficialownershipofsuchsharestotheextentattributedtosuchmembersolelybyvirtueofservingonGPEB.TheaddressforourParentandBCEMis4,rueLouHemmer,L-1748Luxembourg,GrandDuchyofLuxembourg.EuropeFundIIIhasanaddressofUglandHouse,SouthChurchStreet,GeorgeTown,GrandCayman,KY1-1104CaymanIslandsandBCIhasanaddressc/oBainCapitalPartners,LP,200ClarendonStreet,Boston,Massachusetts02116.TheaddressofMr.Hauserisc/oBainCapitalBeteiligungsberatungGmbHMaximilianstrasse11,80539Munich,Germany.

Page 53: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

PLAN OF DISTRIBUTION

Thesellingshareholderwillsellthesecuritiesofferedherebyinoneormoreofthefollowingways(orinanycombinationthere)fromtimetotime:

• toorthroughunderwriters;

• throughagents;

• throughbrokersordealers;

• directlytopurchasers,includingthroughaspecificbidding,auctionorotherprocessorinprivatelynegotiatedtransactions;

• throughacombinationofsuchmethods;or

• throughanyothermethodpermittedbyapplicablelaw.

Aprospectussupplementwilldescribethetermsoftheofferingoftheordinaryshares,includingthefollowing:

• thenameornamesofanyunderwriters,dealersoragentsandtheamountofordinarysharesunderwrittenorpurchasedbyeachofthem;

• thepublicofferingpriceoftheordinaryshares,theproceedstothesellingshareholder,andanydiscounts,commissionsorconcessionsallowedorreallowedorpaidtounderwriters,dealersoragents,andotheritemsconstitutingunderwriters',dealers'oragents'compensation;

• anydelayeddeliveryarrangements;and

• informationaboutthesellingshareholder,includingtherelationshipbetweenthesellingshareholderandus.

Anyofferingpriceandanydiscountsorconcessionsallowedorreallowedorpaidtodealerswillbespecifiedintheprospectussupplementandmaybechangedfromtimetotime.

Onlytheagentsorunderwritersnamedintheprospectussupplementareagentsorunderwritersinconnectionwiththeordinarysharesbeingofferedthereby.

Thesellingshareholdermayauthorizeunderwriters,dealersorotherpersonsactingasouragentstosolicitoffersbycertaininstitutionstopurchasesecuritiesfromthesellingshareholderpursuanttodelayeddeliverycontractsprovidingforpaymentanddeliveryonthedatestatedineachapplicableprospectussupplement.Eachcontractwillbeforanamountnotlessthan,andtheaggregateamountofsecuritiessoldpursuanttosuchcontractsshallnotbelessnormorethan,therespectiveamountsstatedineachapplicableprospectussupplement.Institutionswithwhomthecontracts,whenauthorized,maybemadeincludecommercialandsavingsbanks,insurancecompanies,pensionfunds,investmentcompanies,educationalandcharitableinstitutionsandotherinstitutions,butshallinallcasesbesubjecttoourapproval.Delayeddeliverycontractswillbesubjectonlytothoseconditionssetforthintheprospectussupplement,andtheprospectussupplementwillsetforthanycommissionswepayforsolicitationofthesecontracts.

Agents,underwritersandotherthirdpartiesdescribedabovemaybeentitledtoindemnificationbyusandthesellingshareholderagainstcertaincivilliabilities,includingliabilitiesundertheSecuritiesAct,ortocontributionfromusandthesellingshareholderwithrespecttopaymentswhichtheagents,underwritersorthirdpartiesmayberequiredtomakeinrespectthereof.Agents,underwritersandsuchotherthirdpartiesmaybecustomersof,engageintransactionswith,orperformservicesforusorthesellingshareholderintheordinarycourseofbusiness.Weandthesellingshareholdermayalsouseunderwritersorsuchotherthirdpartieswithwhomweorsuchsellingshareholderhaveamaterial

7

Page 54: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

relationship.Weandthesellingshareholderwilldescribethenatureofanysuchrelationshipintheapplicableprospectussupplement.

Certainunderwritersmayusethisprospectusandanyaccompanyingprospectussupplementforoffersandsalesrelatedtomarket-makingtransactionsinourordinaryshares.Theseunderwritersmayactasprincipaloragentinthesetransactions,andthesaleswillbemadeatpricesrelatedtoprevailingmarketpricesatthetimeofsale.Anyunderwritersinvolvedinthesaleofourordinarysharesmayqualifyas"underwriters"withinthemeaningofSection2(a)(11)oftheSecuritiesAct.Inaddition,theunderwriters'commissions,discountsorconcessionsmayqualifyasunderwriters'compensationundertheSecuritiesActandtherulesoftheFinancialIndustryRegulatoryAuthority.

OurordinarysharesarelistedonTheNewYorkStockExchange.Underwritersmaymakeamarketinourordinaryshares,butwillnotbeobligatedtodosoandmaydiscontinueanymarketmakingatanytimewithoutnotice.Wecanmakenoassuranceastothedevelopment,maintenanceorliquidityofanytradingmarketinourordinaryshares.

Certainpersonsparticipatinginanofferingmayengageinoverallotment,stabilizingtransactions,shortcoveringtransactionsandpenaltybidsinaccordancewithrulesandregulationsundertheSecuritiesExchangeActof1934,asamended(the"ExchangeAct").Overallotmentinvolvessalesinexcessoftheofferingsize,whichcreateashortposition.Stabilizingtransactionspermitbidstopurchasetheunderlyingsecuritysolongasthestabilizingbidsdonotexceedaspecifiedmaximum.Shortcoveringtransactionsinvolvepurchasesoftheordinarysharesintheopenmarketafterthedistributioniscompletedtocovershortpositions.Penaltybidspermittheunderwriterstoreclaimasellingconcessionfromadealerwhentheordinarysharesoriginallysoldbythedealerarepurchasedinacoveringtransactiontocovershortpositions.Thoseactivitiesmaycausethepriceoftheordinarysharestobehigherthanitwouldotherwisebe.Ifcommenced,theunderwritersmaydiscontinueanyoftheactivitiesatanytime.

8

Page 55: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

LEGAL MATTERS

CertainlegalmattersinconnectionwiththisofferingwillbepasseduponforusbyRopes&GrayLLP,Boston,Massachusetts.Ropes&GrayLLPandsomeofitsattorneysarelimitedpartnersofRGIP,LP,whichisaninvestorincertaininvestmentfundsadvisedormanagedbyBainCapitalPartners,LPandoftenaco-investorwithsuchfunds.RGIP,LPindirectlyownslessthan1%ofouroutstandingordinaryshares.ThevalidityoftheissuanceofordinarysharestobesoldinthisofferingwillbepasseduponforusbyLoyens&LoeffLuxembourgS.à.r.l.,Luxembourg.

EXPERTS

TheauditedfinancialstatementsofTrinseoS.A.incorporatedinthisProspectusbyreferencetotheAnnualReportonForm10-KfortheyearendedDecember31,2015,exceptastheyrelatetoAmericasStyrenicsLLC,andtheeffectivenessofinternalcontroloverfinancialreportingasofDecember31,2015havebeenauditedbyPricewaterhouseCoopersLLP,anindependentregisteredpublicaccountingfirm.Suchfinancialstatements,exceptastheyrelatetoAmericasStyrenicsLLC,andmanagement'sassessmentoftheeffectivenessofinternalcontroloverfinancialreportinghavebeensoincorporatedinrelianceonthereportofsuchindependentregisteredpublicaccountingfirmgivenontheauthorityofsaidfirmasexpertsinauditingandaccounting.

TheconsolidatedfinancialstatementsofAmericasStyrenicsLLC,incorporatedinthisprospectusbyreferencefromTrinseoS.A.'sAnnualReportonForm10-KfortheyearendedDecember31,2015,havebeenauditedbyDeloitte&ToucheLLP,anindependentregisteredpublicaccountingfirm,asstatedintheirreport,whichisincorporatedhereinbyreference.Suchfinancialstatementshavebeensoincorporatedinrelianceuponthereportofsuchfirmgivenupontheirauthorityasexpertsinaccountingandauditing.

WHERE YOU CAN FIND MORE INFORMATION

WehavefiledwiththeSECaregistrationstatementonFormS-3undertheSecuritiesActwithrespecttoourordinarysharesbeingofferedbythisprospectus.Thisprospectus,whichformsapartoftheregistrationstatement,doesnotcontainalloftheinformationsetforthintheregistrationstatement.Forfurtherinformationwithrespecttousandtheordinaryshares,referenceismadetotheregistrationstatementandtheexhibitsandschedulesfiledasapartthereof.Statementscontainedinthisprospectusastothecontentsofanycontractorotherdocumentarenotnecessarilycomplete.WearesubjecttotheinformationalrequirementsoftheSecuritiesExchangeActof1934and,inaccordancetherewith,wefilereportsandotherinformationwiththeSEC.Theregistrationstatement,suchreportsandotherinformationcanbeinspectedandcopiedatthePublicReferenceRoomoftheSEClocatedat100FStreet,N.E.,Washington,D.C.20549.Copiesofsuchmaterials,includingcopiesofalloranyportionoftheregistrationstatement,canbeobtainedfromthePublicReferenceRoomoftheSECatprescribedrates.YoucancalltheSECat1-800-SEC-0330toobtaininformationontheoperationofthePublicReferenceRoom.ThesematerialsmayalsobeaccessedelectronicallyfromtheSEC'swebsite,www.sec.gov.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

TheSECallowsusto"incorporatebyreference"intothisprospectusinformationwefilewithit,whichmeansthatwecandiscloseimportantinformationtoyoubyreferringtothesedocuments.TheinformationincorporatedbyreferenceisconsideredtobepartofthisprospectusandinformationindocumentsthatwefilelaterwiththeSECwillautomaticallyupdateandsupersedeinformationinthisprospectus.WeincorporatebyreferenceintothisprospectusthedocumentslistedbelowandanyfuturefilingsmadebyuswiththeSECunderSection13(a),13(c),14,or15(d)oftheExchangeAct,exceptforinformationfurnishedunderItems2.02,7.01,or9.01onForm8-Korotherinformation"furnished"

9

Page 56: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

totheSECwhichisnotdeemedfiledandnotincorporatedinthisprospectus,untiltheterminationoftheofferingofsecuritiesdescribedintheapplicableprospectussupplement.Weherebyincorporatebyreferencethefollowingdocuments:

• OurannualreportonForm10-KfortheyearendedDecember31,2015,filedwiththeSEConMarch11,2016(FileNo.001-36473),andasamendedonMarch15,2016;

• OurcurrentreportsonForm8-KfiledwiththeSEConJanuary26,2016andFebruary26,2016;and

• ThedescriptionofourordinarysharescontainedintheRegistrationStatementonForm8-A,asfiledwiththeSEConJune2,2014(FileNo.001-36473).

Youmayrequestacopyofthesefiling,atnocost,bywritingortelephoningusat:

TrinseoS.A.Attn:CorporateSecretary

1000ChesterbrookBoulevardSuite300

Berwyn,PA19312(610)240-3200

Copiesofthefilingsarealsoavailable,withoutchargeontheSEC'swebsite,www.sec.gov,andonourwebsite,www.trinseo.com,assoonasreasonablypracticableaftertheyarefiledelectronicallywiththeSEC.Theinformationcontainedonourwebsiteisnotapartofthisprospectus.

10

Page 57: d18rn0p25nwr6d.cloudfront.netd18rn0p25nwr6d.cloudfront.net/CIK-0001519061/df12b3c3-928d-442… · Use these links to rapidly review the document Table of Contents Table of Contents

TableofContents

Trinseo S.A.10,669,567 Ordinary Shares

PROSPECTUS SUPPLEMENT

Morgan Stanley