EX-4.9

~~Director~~/Secretary

Authorised Signatory

First Names Corporate Secretaries Ltd

Company Secretary

FOURTH SUPPLEMENTAL INDENTURE, (this “Supplemental Indenture”) dated as of December 3, 2013, by and among the parties that are signatories hereto as Guarantors (each, a “Guarantor” and, together, the “Guarantors”), Trinseo Materials Operating S.C.A, a corporate partnership limited by shares (société en commandite par actions) organized and existing under the laws of the Grand Duchy of Luxembourg , having its registered office at 4, rue Lou Hemmer, L-1748 Luxembourg-Findel and registered with the Luxembourg Trade and Companies Register under number B 153586 (the “Company”), Trinseo Materials Finance, Inc., a Delaware corporation (“Trinseo Finance” and, together with the Company, the “Issuers”) and Wilmington Trust, National Association, as Trustee and Collateral Agent under the Indenture referred to below.

WHEREAS, each of the Issuers, the Guarantors and the Trustee and Collateral Agent have heretofore executed and delivered an indenture dated as of January 29, 2013 (as amended, supplemented, waived or otherwise modified, the “Indenture”), providing for the issuance of an aggregate principal amount of $1,325.0 million of 8.750% Senior Secured Notes due 2019 of the Issuers (the “Notes”);

WHEREAS, the Issuers, the Trustee and certain direct and indirect parents of the Company (the “Guaranteeing Parents”) previously executed a first supplemental indenture, dated March 12, 2013 (the “First Supplemental Indenture”);

WHEREAS, the Issuers, the Trustee and the Guarantors previously executed a second supplemental indenture, dated May 10, 2013 (the “Second Supplemental Indenture”);

WHEREAS, the Issuers, the Trustee and the Guarantors previously executed a third supplemental indenture, dated September 16, 2013 (the “Third Supplemental Indenture”); and

WHEREAS, pursuant to Section 9.1 of the Indenture, the Issuers, any Guarantor and the Trustee are authorized to execute and deliver a Supplemental Indenture to amend or supplement the Indenture, without the consent of any Holder to make any change that does not adversely affect the rights of any Holder in any material respect;

NOW, THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the Issuers, the Guarantors and the Trustee mutually covenant and agree for the equal and ratable benefit of the Holders of the Notes as follows:

SECTION 1.1. Defined Terms. As used in this Supplemental Indenture, terms defined in the Indenture or in the preamble or recitals hereto are used herein as therein defined. The words “herein,” “hereof” and “hereby” and other words of similar import used in this Supplemental Indenture refer to this Supplemental Indenture as a whole and not to any particular section hereof.

SECTION 3.1. Amendment of Section 2.3. Section 2.3(a) of the Second Supplemental Indenture is hereby amended and restated in its entirety to read as follows:

“The restrictions in this Section 2.3 shall apply only to any Guaranty granted by a Guarantor incorporated under the laws of Switzerland. To the extent that (i) each Guaranteeing Subsidiary becomes,

under Article X of the Indenture or under any other provision of any Notes Document, the Registration Rights Agreement or the Purchase Agreement (together the “Transaction Document”), liable for Guaranteed Obligations of its Affiliates (other than those of its direct or indirect wholly owned Subsidiaries) or otherwise obliged to grant economic benefits to its Affiliates (other than its direct or indirect wholly owned Subsidiaries), including, for the avoidance of doubt, any joint liability and/or restrictions of such Guaranteeing Subsidiary’s rights of set-off and/or subrogation or its duties to subordinate or waive claims and (ii) complying with such obligations would constitute a repayment of capital (Einlagerückgewähr), a violation of the legally protected reserves (gesetzlich geschützte Reserven) or the payment of a (constructive) dividend (Gewinnausschüttung) by such Guaranteeing Subsidiary or would otherwise be restricted under Swiss corporate law then applicable (the “Restricted Obligations”), the aggregate liability of such Guaranteeing Subsidiary for Restricted Obligations shall be limited to the amount permitted to be paid under applicable law, provided that such limitation shall not discharge such Guaranteeing Subsidiary from its obligations in excess thereof, but merely postpone the performance date therefore until such times as performance is again permitted notwithstanding such limitation. Any and all indemnities and guarantees contained in the Transaction Documents shall be construed in a manner consistent with the provisos herein contained.”

SECTION 3.2. Amendment of Section 2.4. Section 2.4 of the Second Supplemental Indenture is hereby amended and restated in its entirety to read as follows:

“Notwithstanding any other provision of the Indenture, and in particular Article X, a Guarantor (a “German Guarantor”) incorporated under the laws of the Federal Republic of Germany as a limited liability company (Gesellschaft mit beschränkter Haftung) may refuse to make any payments under the Guaranty to the extent any such payment would result in a violation of Sections 30 et seq. or Section 63 sentence 3 of German Limited Liability Companies Act (Gesetz betreffend die Gesellschaften mit beschränkter Haftung) or Section 826 of the German Civil Code (Bürgerliches Gesetzbuch) or would otherwise lead to personal liability of the managing directors (Geschäftsführer) of the German Guarantor. Each German Guarantor covenants to use all commercially reasonable efforts to maximize the amount payable under the Guarantee in accordance with applicable German law.”

SECTION 3.3. Amendment of Section 2.5. Section 2.5(b) of the Second Supplemental Indenture is hereby amended and restated in its entirety to read as follows:

“Notwithstanding any other provision of the Indenture or the Notes, the obligations of a Belgian Guarantor under the Indenture in respect of its Guaranteed Obligations and any amounts guaranteed by it under the Credit Agreement shall be limited to the aggregate maximum amount (if any) permitted under applicable Belgian law.”

SECTION 3.4. Amendment of Section 2.9. Section 2.9(b) of the Second Supplemental Indenture is hereby amended and restated in its entirety to read as follows:

“Notwithstanding any other provision of the Indenture or the Notes, the obligations of a Luxembourg Guarantor under the Indenture in respect of its Guaranteed Obligations and any amounts guaranteed by it under the Credit Agreement shall be limited to the aggregate maximum amount (if any) permitted under applicable Luxembourg law.”

SECTION 3.1. Parties. Nothing expressed or mentioned herein is intended or shall be construed to give any Person, firm or corporation, other than the Holders and the Trustee, any legal or equitable right, remedy or claim under or in respect of this Supplemental Indenture or the Indenture or any provision herein or therein contained.

SECTION 3.2. Governing Law. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK. THE PROVISIONS OF SECTION 13.10 (JURISDICTION) OF THE INDENTURE SHALL APPLY TO THIS SUPPLEMENTAL INDENTURE. THE APPLICATION OF THE PROVISIONS SET OUT IN ARTICLES 86 TO 94-8 OF THE LUXEMBOURG LAW ON COMMERCIAL COMPANIES DATED AUGUST 10, 1915 IS EXCLUDED.

SECTION 3.3. Severability. In case any provision in this Supplemental Indenture shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby and such provision shall be ineffective only to the extent of such invalidity, illegality or unenforceability.

SECTION 3.4. Ratification of Indenture; Supplemental Indentures Part of Indenture. Except as expressly amended hereby, the Indenture is in all respects ratified and confirmed and all the terms, conditions and provisions thereof shall remain in full force and effect. This Supplemental Indenture shall form a part of the Indenture for all purposes, and every Holder of Notes heretofore or hereafter authenticated and delivered shall be bound hereby.

SECTION 3.5. The Trustee. The Trustee makes no representation or warranty as to the validity or sufficiency of this Supplemental Indenture or with respect to the recitals contained herein, all of which recitals are made solely by the other parties hereto.

SECTION 3.6. Counterparts. The parties hereto may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them together represent the same agreement. The exchange of copies of this Supplemental Indenture and of signature pages by facsimile or PDF transmission shall constitute effective execution and delivery of this Supplemental Indenture as to the parties hereto and may be used in lieu of the original Supplemental Indenture for all purposes. Signatures of the parties hereto transmitted by facsimile or PDF shall be deemed to be their original signatures for all purposes.

SECTION 3.7. Headings. The headings of the Articles and the Sections in this Supplemental Indenture are for convenience of reference only and shall not be deemed to alter or affect the meaning or interpretation of any provisions hereof.

IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed as of the date first above written.


TRINSEO MATERIALS OPERATING S.C.A. Acting Through its general partner Trinseo Materials S.à r.l.

By:

	Name:	John A. Feenan
	Title:	Authorized Signatory


TRINSEO MATERIALS FINANCE, INC.

By:

	Name:	John A. Feenan
	Title:	Executive Vice President and CFO


TRINSEO S.A. Société anonyme 4, rue Lou Hemmer, L-1748 Luxembourg-Findel R.C.S. Luxembourg: B 153.549 as a Guarantor

By:

	Name:	Ailbhe Jennings
	Title:	Manager


STYRON LUXCO S.À R.L. Société à responsabilité limitée 4, me Lou Hemmer, L-1748 Luxembourg-Findel R.C.S. Luxembourg: B 153.577 Share Capital: USD 162,815,835.14 as a Guarantor

By:

	Name:	Ailbhe Jennings
	Title:	Manager


TRINSEO MATERIALS S.À R.L. Société à responsabilité limitée 4, rue Lou Hemmer, L-1748 Luxembourg-Findel R.C.S. Luxembourg: B 162.639 Share Capital: USD 23,517,398.72 as a Guarantor

By:

	Name:	Ailbhe Jennings
	Title:	Manager


STYRON HOLDING S.À R.L. Société à responsabilité limitée 4, rue Lou Hemmer, L-1748 Luxembourg-Findel R.C.S. Luxembourg: B 153.582 Share Capital: USD 162,815,834.12 as a Guarantor

By:

	Name:	Ailbhe Jennings
	Title:	Manager


STYRON US HOLDING, INC., as a Guarantor

By:

	Name:	John A. Feenan
	Title:	Executive Vice President and CFO

STYRON LLC, as a Guarantor

By:

	Name:	John A. Feenan
	Title:	Executive Vice President and CFO


STYRON HOLDING B.V. as a Guarantor

By:

	Name:	F.J.C.M. Kempenaars
	Title:	Director	F.J.C.M. Kempenaars Director Styron Holding B.V.


STYRON NETHERLANDS B.V. as a Guarantor

By:			F.J.C.M. Kempenaars
	Name:		Director
	Title:	Director	Styron Netherlands B.V.

By:
	Name:	R.T.C. van Beelen
	Title:	Director
		Director
		Styron Netherlands B.V.


STYRON FINANCE LUXEMBOURG S.À R.L. Société à responsabilité limitée 4, rue Lou Hemmer, L-1748 Luxembourg-Findel R.C.S. Luxembourg: B 151.012 Share Capital: USD 25,001.- as a Guarantor

By:
	Name:	Ailbhe Jennings
		Manager
	Title:	Authorized Signature


Styron Deutschland GmbH

By:
	Name:	Ralf Irmert
	Title:	Managing Director

Styron Deutschland Anlagengesellschaft mbH

By:
	Name:	Hans-Heinrich Neuhaus
	Title:	Managing Director


Styron Deutschland GmbH

By:

	Name:	Ralf lrmert
	Title:	Managing Director

Styron Deutschland Anlagengesellschaft mbH

By:

	Name:	Hans-Heinrich Neuhaus
	Title:	Managing Director

IN WITNESS WHEREOF, Styron (Hong Kong) Limited has caused this Supplemental Indenture to be duly executed and delivered as a deed, as of the date first above written.


STYRON UK LIMITED as a Guarantor

By:

	Name:	Walter Bosschieter
	Title:	Director


STYRON SVERIGE AB,
as a Guarantor

By:
	Name:	Erkki Kesti,
	Title:	Authorised Signatory


WILMINGTON TRUST, NATIONAL ASSOCIATION, as Trustee

By:
	Name:	Jane Schweiger
	Title:	Vice President


SEALED with the COMMON SEAL of STYRON (HONG KONG) LIMITED and SIGNED by Lee Chung Lok,


[Signature of Director]
Director
in the presence of:


[Signature of Witness]
Name of Witness: Rachel Lau
Address of Witness: 40-50 Tsing Yi Road, NT, HK
Occupation of Witness: Administrative Specialist


Executed by Styron Australia Pty Ltd in accordance with section 127 of the Corporations Act 2001 (Cth):



Signature of director				Signature of company secretary/director

Mark Stewart Tucker				Tim Thomas
Full name of director				Full name of company secretary/director


The COMMON SEAL of		)
STYRON HOLDINGS ASIA PTE. LTD.		)
was hereunto affixed in accordance with its		)
Articles of Association:		)

Director Dongyu Cai

~~Director~~/Secretary
Catherine Lim Siok Ching


The COMMON SEAL of		)
STYRON SINGAPORE PTE. LTD.		)
was hereunto affixed in accordance with its		)
Articles of Association:		)

Director Dongyu Cai

~~Director~~/Secretary
Catherine Lim Siok Ching


STYRON BELGIUM BVBA,
as a Guarantor

By:

	Name:	R.M. Van Domburg
	Title:	Director


STYRON CANADA ULC

PER:

	Name:	Marina M. Zivik
	Title:	President


STYRON EUROPE GMBH,
as a Guarantor

By:

	Name:	Dr. Isabel Hacker
	Title:	Director