10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)                                                                                                                                                                                         

☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2024

or

☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
EXCHANGE ACT OF 1934

For the transition period from                      to                     

Commission File Number: 001-36473

Trinseo PLC

(Exact name of registrant as specified in its charter)

Ireland	N/A
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

440 East Swedesford Road

Suite 301

Wayne, PA 19087

(Address of Principal Executive Offices)

(610) 240-3200

(Registrant’s telephone number)

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

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

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

Large accelerated filer	◻	Accelerated filer	☒
Non-accelerated filer	◻	Smaller reporting company	☐	Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

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

Securities registered pursuant to Section 12(b) of the Act:

Title of Each Class	Trading symbol	Name of Exchange on which registered
Ordinary Shares, par value $0.01 per share	TSE	New York Stock Exchange

As of May 3, 2024, there were 35,294,231 of the registrant’s ordinary shares outstanding.

TABLE OF CONTENTS

`
		Page
Part I	Financial Information
Item 1.	Financial Statements	4
	Condensed Consolidated Balance Sheets as of March 31, 2024 and December 31, 2023 (Unaudited)	4
	Condensed Consolidated Statements of Operations for the three months ended March 31, 2024 and 2023 (Unaudited)	5
	Condensed Consolidated Statements of Comprehensive Income (Loss) for the three months ended March 31, 2024 and 2023 (Unaudited)	6
	Condensed Consolidated Statements of Shareholders’ Equity for the three months ended March 31, 2024 and 2023 (Unaudited)	7
	Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2024 and 2023 (Unaudited)	8
	Notes to Condensed Consolidated Financial Statements (Unaudited)	9
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	31
Item 3.	Quantitative and Qualitative Disclosures about Market Risk	41
Item 4.	Controls and Procedures	41
Part II	Other Information
Item 1.	Legal Proceedings	41
Item 1A.	Risk Factors	42
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	42
Item 3.	Defaults Upon Senior Securities	42
Item 4.	Mine Safety Disclosures	42
Item 5.	Other Information	42
Item 6.	Exhibits	42
Exhibit Index
Signatures

2

Trinseo PLC

Quarterly Report on Form 10-Q

For the quarterly period ended March 31, 2024

Unless otherwise indicated or required by context, as used in this Quarterly Report on Form 10-Q (“Quarterly Report”), the term “Trinseo PLC” refers to Trinseo PLC (NYSE: TSE), a public limited company existing under the laws of Ireland, and not its subsidiaries. The terms “Trinseo”, the “Company,” “we,” “us” and “our” refer to Trinseo PLC and its consolidated subsidiaries, taken as a consolidated entity. All financial data provided in this Quarterly Report is the financial data of Trinseo PLC, unless otherwise indicated. Prior to the formation of the Company, our business was wholly owned by The Dow Chemical Company (together with other affiliates, “Dow”). The Company may distribute cash to shareholders under Irish law via dividends or distributions made from distributable profits.

Definitions of capitalized terms not defined herein appear within our Annual Report on Form 10-K for the year ended December 31, 2023 (“Annual Report”) filed with the Securities and Exchange Commission (“SEC”) on February 23, 2024.

Cautionary Note on Forward-Looking Statements

This Quarterly Report contains, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategies, future events or performance, and underlying assumptions and other statements, which are not statements of historical facts. Forward-looking statements may be identified by the use of words like “expect,” “anticipate,” “believe,” “intend,” “forecast,” ”estimate,” “see,” “outlook,” “will,” “may,” “might,” “potential,” “likely,” “target,” “plan,” “contemplate,” “seek,” “attempt,” “should,” “could,” “would,” or expressions of similar meaning. Forward-looking statements reflect management’s evaluation of information currently available and are based on our current expectations and assumptions regarding our business, the economy, our current indebtedness and other future conditions. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict.

Specific factors that may cause future results to differ from those expressed by the forward-looking statements, or otherwise impact performance or other predictions of future actions have, in many but not all cases, been identified in connection with specific forward-looking statements. Factors that might cause future results to differ from those expressed by the forward-looking statements include, but are not limited to, our ability to successfully implement proposed restructuring initiatives, including the closure of certain plants and product lines, and to successfully generate cost savings and increase profitability; our ability to successfully execute our business and transformation strategy; increased costs or disruption in the supply of raw materials; increased energy costs; compliance with laws and regulations impacting our business; conditions in the global economy and capital markets; our ability to achieve our forecast cash flows and maintain covenants under our existing indebtedness; our ability to successfully investigate and remediate chemical releases on or from our sites, make related capital expenditures, reimburse third-party cleanup costs or settle potential regulatory penalties or other claims; and those discussed in our Annual Report filed with the SEC on February 23, 2024 under Part I, Item IA— “Risk Factors,” within this Quarterly Report and in other filings and furnishings made by the Company with the SEC from time to time.

As a result of these or other factors, our actual results, performance or achievements may differ materially from those contemplated by the forward-looking statements. They are neither statements of historical fact nor guarantees or assurances of future performance. Therefore, we caution you against relying on these forward-looking statements. The forward-looking statements included in this Quarterly Report are made only as of the date hereof. We undertake no obligation to publicly update or revise any forward-looking statement as a result of new information, future events or otherwise, except as otherwise required by law.

Available Information

Our annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K, and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, are available free of charge through the Investor Relations section of our website, www.trinseo.com, as soon as reasonably practicable after the reports are electronically filed or furnished with the SEC. We provide this website and information contained in or connected to it for informational purposes only. That information is not a part of this Quarterly Report.

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PART I —FINANCIAL INFORMATION

Item 1. Financial Statements

TRINSEO PLC

Condensed Consolidated Balance Sheets

(In millions, except per share data)

(Unaudited)

	March 31,		December 31,
	2024		2023
Assets
Current assets
Cash and cash equivalents	$	166.4	$	259.1
Accounts receivable, net of allowance for doubtful accounts (March 31, 2024: $6.6; December 31, 2023: $6.7)		556.5		490.8
Inventories		431.2		404.7
Other current assets		42.6		39.5
Total current assets		1,196.7		1,194.1
Investments in unconsolidated affiliate		258.4		252.2
Property, plant and equipment, net of accumulated depreciation (March 31, 2024: $775.9; December 31, 2023: $778.2)		624.2		643.7
Other assets
Goodwill		62.3		63.8
Other intangible assets, net		668.3		693.9
Right-of-use assets - operating, net		60.7		65.3
Deferred income tax assets		46.6		44.3
Deferred charges and other assets		72.2		71.9
Total other assets		910.1		939.2
Total assets	$	2,989.4	$	3,029.2
Liabilities and shareholders’ equity
Current liabilities
Short-term borrowings and current portion of long-term debt	$	21.1	$	20.9
Accounts payable		478.9		449.7
Current lease liabilities - operating		15.5		16.3
Income taxes payable		13.8		10.9
Accrued expenses and other current liabilities		202.7		174.8
Total current liabilities		732.0		672.6
Noncurrent liabilities
Long-term debt, net of unamortized deferred financing fees		2,276.7		2,277.6
Noncurrent lease liabilities - operating		47.5		51.7
Deferred income tax liabilities		41.2		43.5
Other noncurrent obligations		240.0		251.8
Total noncurrent liabilities		2,605.4		2,624.6
Commitments and contingencies (Note 13)
Shareholders’ equity
Ordinary shares, $0.01 nominal value, 4,000.0 shares authorized (March 31, 2024: 39.4 shares issued and 35.3 shares outstanding; December 31, 2023: 39.4 shares issued and 35.2 shares outstanding)		0.4		0.4
Preferred shares, €0.01 nominal value, 1,000.0 shares authorized (no shares issued or outstanding)		—		—
Deferred ordinary shares, €1.00 nominal value, 0.025 shares authorized (March 31, 2024: 0.025 shares issued and outstanding; December 31, 2023: 0.025 shares issued and outstanding)		—		—
Additional paid-in-capital		507.8		504.2
Treasury shares, at cost (March 31, 2024: 4.1 shares; December 31, 2023: 4.1 shares)		(200.0)		(200.0)
Accumulated deficit		(518.8)		(443.0)
Accumulated other comprehensive loss		(137.4)		(129.6)
Total shareholders’ equity		(348.0)		(268.0)
Total liabilities and shareholders’ equity	$	2,989.4	$	3,029.2

The accompanying notes are an integral part of these condensed consolidated financial statements.

4

TRINSEO PLC

Condensed Consolidated Statements of Operations

(In millions, except per share data)

(Unaudited)

	Three Months Ended
	March 31,
	2024		2023
Net sales	$	904.0	$	996.3
Cost of sales		843.4		959.1
Gross profit		60.6		37.2
Selling, general and administrative expenses		70.1		84.7
Equity in earnings of unconsolidated affiliate		6.2		17.6
Impairment and other charges		—		0.3
Operating loss		(3.3)		(30.2)
Interest expense, net		63.0		38.3
Other expense (income), net		3.8		(2.9)
Loss before income taxes		(70.1)		(65.6)
Provision for (benefit from) income taxes		5.4		(16.7)
Net loss	$	(75.5)	$	(48.9)
Weighted average shares‒basic		35.3		35.0
Net loss per share‒basic	$	(2.14)	$	(1.40)
Weighted average shares‒diluted		35.3		35.0
Net loss per share‒diluted:	$	(2.14)	$	(1.40)

The accompanying notes are an integral part of these condensed consolidated financial statements.

5

TRINSEO PLC

Condensed Consolidated Statements of Comprehensive Income (Loss)

(In millions)

(Unaudited)

	Three Months Ended
	March 31,
	2024		2023
Net loss	$	(75.5)	$	(48.9)
Other comprehensive income (loss), net of tax:
Cumulative translation adjustments (net of tax of $0.0 and $0.0)		(11.8)		10.5
Net gain (loss) on cash flow hedges (net of tax of $(1.7) and $(2.5))		4.4		(7.4)
Pension and other postretirement benefit plans:
Amounts reclassified from accumulated other comprehensive income (loss)		(0.4)		0.3
Total other comprehensive income (loss), net of tax		(7.8)		3.4
Comprehensive loss	$	(83.3)	$	(45.5)

The accompanying notes are an integral part of these condensed consolidated financial statements.

6

TRINSEO PLC

Condensed Consolidated Statements of Shareholders’ Equity

(In millions, except per share data)

(Unaudited)

	Shares			Shareholders' Equity
	Ordinary Shares Outstanding	Treasury Shares	Deferred Ordinary Shares	Ordinary Shares		Deferred Ordinary Shares		Additional Paid-In Capital		Treasury Shares		Accumulated Other Comprehensive Income Loss		Retained Earnings (Accumulated Deficit)		Total
Balance at December 31, 2023	35.2	4.1	—	$	0.4	$	—	$	504.2	$	(200.0)	$	(129.6)	$	(443.0)	$	(268.0)
Net loss	—	—	—		—		—		—		—		—		(75.5)		(75.5)
Other comprehensive loss	—	—	—		—		—		—		—		(7.8)		—		(7.8)
Share-based compensation activity	0.1	—	—		—		—		3.6		—		—		—		3.6
Dividends on ordinary shares ($0.01 per share)	—	—	—		—		—		—		—		—		(0.3)		(0.3)
Balance at March 31, 2024	35.3	4.1	—	$	0.4	$	—	$	507.8	$	(200.0)	$	(137.4)	$	(518.8)	$	(348.0)
Balance at December 31, 2022	35.1	4.1	—	$	0.4	$	—	$	486.7	$	(200.0)	$	(131.3)	$	264.5	$	420.3
Net loss	—	—	—		—		—		—		—		—		(48.9)		(48.9)
Other comprehensive income	—	—	—		—		—		—		—		3.4		—		3.4
Share-based compensation activity	0.1	—	—		—		—		6.6		—		—		—		6.6
Dividends on ordinary shares ($0.14 per share)	—	—	—		—		—		—		—		—		(5.2)		(5.2)
Balance at March 31, 2023	35.2	4.1	—	$	0.4	$	—	$	493.3	$	(200.0)	$	(127.9)	$	210.4	$	376.2

The accompanying notes are an integral part of these condensed consolidated financial statements.

7

TRINSEO PLC

Condensed Consolidated Statements of Cash Flows

(In millions)

(Unaudited)

	Three Months Ended
	March 31,
	2024		2023
Cash flows from operating activities
Net loss	$	(75.5)	$	(48.9)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Depreciation and amortization		45.0		56.0
Amortization of deferred financing fees and issuance discount		3.7		2.3
Deferred income tax benefit		(3.8)		(16.6)
Share-based compensation expense		5.9		8.2
Earnings of unconsolidated affiliate, net of dividends		(6.2)		2.4
Unrealized net (gain) loss on foreign exchange forward contracts		(5.0)		1.5
Unrealized net loss on commodity economic swap contracts		2.4		5.8
Gain on sale of other assets		(3.6)		—
Impairment charges or write-offs		—		0.3
Changes in assets and liabilities
Accounts receivable		(72.6)		(29.2)
Inventories		(31.2)		55.1
Accounts payable and other current liabilities		80.3		26.5
Income taxes payable		2.9		(7.0)
Other assets, net		6.3		3.8
Other liabilities, net		(14.8)		(14.8)
Cash provided by (used in) operating activities		(66.2)		45.4
Cash flows from investing activities
Capital expenditures		(15.7)		(21.8)
Proceeds from the sale of other assets		4.7		—
Cash used in investing activities		(11.0)		(21.8)
Cash flows from financing activities
Deferred financing fees		0.4		—
Short-term borrowings, net		(3.7)		(2.7)
Dividends paid		(0.6)		(11.8)
Proceeds from exercise of option awards		—		0.1
Withholding taxes paid on restricted share units		—		(1.3)
Acquisition-related contingent consideration payment		(0.7)		(1.2)
Repurchases and repayments of long-term debt		(4.6)		(3.6)
Proceeds from Accounts Receivable Securitization Facility		30.0		—
Repayments of Accounts Receivable Securitization Facility		(30.0)		—
Cash used in financing activities		(9.2)		(20.5)
Effect of exchange rates on cash		(3.2)		2.3
Net change in cash, cash equivalents, and restricted cash		(89.6)		5.4
Cash, cash equivalents, and restricted cash—beginning of period		261.1		211.7
Cash, cash equivalents, and restricted cash—end of period	$	171.5	$	217.1
Less: Restricted cash		5.1		—
Cash and cash equivalents—end of period	$	166.4	$	217.1

The accompanying notes are an integral part of these condensed consolidated financial statements.

8

TRINSEO PLC

Notes to Condensed Consolidated Financial Statements

(Dollars in millions, unless otherwise stated)

(Unaudited)

NOTE 1—BASIS OF PRESENTATION

The unaudited interim condensed consolidated financial statements of Trinseo PLC and its subsidiaries (the “Company”) as of and for the periods ended March 31, 2024 and 2023 were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and reflect all adjustments, consisting only of normal recurring adjustments, which, in the opinion of management, are considered necessary for the fair statement of the results for the periods presented. Because they cover interim periods, the statements and related notes to the financial statements do not include all disclosures normally provided in annual financial statements, and therefore, these statements should be read in conjunction with the 2023 audited consolidated financial statements included within the Company’s Annual Report on Form 10-K (“Annual Report”) filed with the Securities and Exchange Commission (“SEC”) on February 23, 2024. The Company’s condensed consolidated financial statements presented herein reflect the latest estimates and assumptions made by management that affect the reported amounts and related disclosures as of and for the period ended March 31, 2024. However, actual results could differ from these estimates and assumptions.

The December 31, 2023 condensed consolidated balance sheet data presented herein was derived from the Company’s December 31, 2023 audited consolidated financial statements, but does not include all disclosures required by GAAP for annual periods.

Effective January 1, 2024, the Company’s Feedstocks segment, which included the Company’s production and procurement of styrene monomer outside of North America, was eliminated as a result of the closures of the styrene plants located in Boehlen, Germany and Terneuzen, the Netherlands under an asset restructuring plan. As a result, the Company realigned its reporting segments to reflect the new model under which the business is managed with five segments, all of which remain unchanged from the Company’s prior six segment segmentation: Engineered Materials, Latex Binders, Plastics Solutions, Polystyrene, and Americas Styrenics. Therefore, certain prior year information has been adjusted to show the historical results of the Feedstocks segment within the segments that consumed styrene monomer in their end products, Latex Binders, Plastics Solutions and Polystyrene. Refer to Notes 3, 4 and 16 for further information. Throughout this Quarterly Report, unless otherwise indicated, amounts and activity are presented on a continuing operations basis.

NOTE 2—RECENT ACCOUNTING GUIDANCE

As of March 31, 2024, there was no recently issued accounting standards which would have a material effect on the Company’s condensed consolidated financial statements.

9

NOTE 3—NET SALES

Refer to the Annual Report for information on the Company's accounting policies and further background related to its net sales.

The following table provides disclosure of net sales to external customers by primary geographical market (based on the location where sales originated), by segment for the three months ended March 31, 2024 and 2023. Prior period balances in this table have been reclassified to reflect the elimination of the Feedstocks reportable segment effective January 1, 2024. Refer to Note 16 for further information.

	Engineered		Latex		Plastics
Three Months Ended	Materials		Binders		Solutions		Polystyrene		Total
March 31, 2024
United States	$	94.7	$	65.3	$	66.4	$	—	$	226.4
Europe		75.3		109.3		142.8		135.1		462.5
Asia-Pacific		16.8		65.7		29.1		72.5		184.1
Rest of World		2.4		1.2		27.4		—		31.0
Total	$	189.2	$	241.5	$	265.7	$	207.6	$	904.0
March 31, 2023
United States	$	110.9	$	67.6	$	72.3	$	—	$	250.8
Europe		73.5		129.0		172.1		170.2		544.8
Asia-Pacific		18.9		50.7		27.8		70.6		168.0
Rest of World		2.9		1.7		28.1		—		32.7
Total	$	206.2	$	249.0	$	300.3	$	240.8	$	996.3

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NOTE 4—RESTRUCTURING ACTIVITIES

Refer to the Annual Report for further details regarding the Company’s previously announced restructuring activities included in the tables below. Restructuring charges are included within “Selling, general and administrative expenses” in the condensed consolidated statements of operations.

The following table provides detail of the Company’s restructuring charges for the three months ended March 31, 2024 and 2023:

	Three Months Ended				Cumulative
	March 31,				Life-to-date
	2024		2023		Charges		Segment
Asset Optimization and Corporate Restructuring(1)
Engineered Materials:
Accelerated depreciation	$	—	$	—	$	9.3	Engineered Materials
Employee termination benefits		—		—		1.2	Engineered Materials
Decommissioning and other		1.1		—		3.7	Engineered Materials
Plastics Solutions(5):
Accelerated depreciation	$	—	$	—	$	19.6	Plastics Solutions
Employee termination benefits		(0.7)		—		4.7	Plastics Solutions
Contract terminations		3.8		—		6.3	Plastics Solutions
Decommissioning and other		1.8		—		6.8	Plastics Solutions
Corporate:
Employee termination benefits	$	1.2	$	—	$	10.0	N/A(2)
Asset Optimization and Corporate Restructuring Subtotal	$	7.2	$	—	$	61.6
Asset Restructuring Plan(3)
Plastics Solutions(5):
Accelerated depreciation	$	—	$	0.9	$	27.4	Plastics Solutions(6)
Employee termination benefits		—		(0.2)		3.7	Plastics Solutions(6)
Contract terminations		1.7		2.5		10.0	Plastics Solutions(6)
Decommissioning and other		0.3		0.5		4.5	Plastics Solutions(6)
Plastics Solutions:
Accelerated depreciation	$	—	$	—	$	1.4	Plastics Solutions
Employee termination benefits		(0.6)		(0.4)		2.4	Plastics Solutions
Decommissioning and other		—		0.7		1.9	Plastics Solutions
Engineered Materials:
Accelerated depreciation	$	—	$	3.1	$	6.3	Engineered Materials
Employee termination benefits		—		—		2.7	Engineered Materials
Decommissioning and other		—		0.6		1.3	Engineered Materials
Asset Restructuring Plan Subtotal	$	1.4	$	7.7	$	61.6
Transformational Restructuring Program(4)
Employee termination benefits	$	—	$	—	$	6.7
Transformational Restructuring Program Subtotal	$	—	$	—	$	6.7	N/A(2)
Total Restructuring Charges	$	8.6	$	7.7

(1) On August 23, 2023, the Company announced a restructuring plan to optimize its polymethyl methacrylates (“PMMA”) sheet network, primarily in Europe, consolidate manufacturing operations and certain other workforce reductions to streamline its general & administrative network. The Asset Optimization and Corporate Restructuring plan includes closure of certain plants and product lines, including (i) closure of manufacturing operations at the Company’s PMMA cast sheets plant in Bronderslev, Denmark, (ii) closure of manufacturing operations at the Company’s batch polyester tray casting plant in Belen, New Mexico, and (iii) closure of its PMMA extruded sheet production line at its Rho, Italy plant.

11

On October 26, 2023, the management team of the Company, with authorization from the Company’s Board of Directors, approved additional actions to discontinue styrene production at the Company’s Terneuzen, the Netherlands plant, decommission the styrene plant assets, as well as related workforce reductions.

During the three months ended March 31, 2024, the Company incurred employee termination benefit charges, net of $0.5 million. The majority of these charges are expected to be paid through second quarter of 2025. The Company also incurred decommissioning and other charges of $2.9 million, as well as contract termination charges of $3.8 million.

The Company expects to incur contract termination charges of $4.8 million and an incremental $16.2 million of decommissioning and other charges through the end of 2025.

In March 2024, the Company entered into two separate agreements to sell its land, buildings and equipment in Bronderslev, Denmark and Belen, New Mexico for gross cash consideration of approximately $4.7 million. As of March 31, 2024, the cash proceeds of $2.9 million were received into the Company’s restricted cash account to be released upon completion of final regulatory documentation. The Company recorded pre-tax gain on sales of $3.6 million during the three ended March 31, 2024, which was recorded within “Selling, general and administrative expenses” in the condensed consolidated statements of operations.

(2) Reflects certain employee termination benefit charges associated with streamlining internal general & administrative network. As these employee termination benefit charges were identified as a corporate-related activity, the charges related to this portion of the Asset Optimization and Corporate Restructuring plan were not allocated to a specific segment, but rather included within corporate unallocated.

(3) In December 2022, the Company announced an asset restructuring plan designed to reduce costs, improve profitability, reduce exposure to cyclical markets and elevated natural gas prices, and address market overcapacity. The asset restructuring plan includes (i) closure of manufacturing operations at the styrene production facility in Boehlen, Germany, (ii) closure of one of its production lines at the Stade, Germany polycarbonate plant, and (iii) closure of the PMMA sheet manufacturing site in Matamoros, Mexico. The program is expected to be substantially completed by 2026.

In connection with this restructuring plan, during the three months ended March 31, 2024 and 2023, the Company incurred employee termination benefit charges, net of $(0.6) million and $(0.6) million, respectively, contract termination charges of $1.7 million and $2.5 million, respectively, and decommissioning and other charges of $0.3 million and $1.8 million, respectively. The Company incurred accelerated depreciation charges of $4.0 million during the three months ended March 31, 2023.

The Company expects to incur incremental contract termination charges of $10.5 million, decommissioning and other charges of $0.5 million, as well as a limited amount of incremental employee termination benefit charges within the Plastics Solution segment, the majority of which is expected to be paid by the end of 2024.

(4) In May 2021, the Company approved a transformational restructuring program associated with the Company’s strategic initiatives. The transformational restructuring program was completed as of December 31, 2023. As this was identified as a corporate-related activity, the charges related to this restructuring program were not allocated to a specific segment, but rather included within corporate unallocated.

(5) As of January 2024, the Feedstocks segment was eliminated as a result of the closures of the styrene plants located in Boehlen, Germany and Terneuzen, the Netherlands under an asset restructuring plan. Prior period balances in this table have been reclassified to reflect the elimination of the Feedstocks reportable segment effective January 1, 2024. Asset Optimization charges relate to Terneuzen plant shutdown and Asset Restructuring Plan charges relate to the shutdown of Boehlen site. These charges were previously recognized under Feedstocks segment but will be allocated to Plastics Solutions segment starting January 1, 2024 and onward.

(6) Prior period balances in this table have been reclassified to reflect the elimination of the Feedstocks reportable segment effective January 1, 2024. For the three months ended March 31, 2023, Latex Binders was allocated $0.1 million of accelerated depreciation, $0.4 million of contract termination costs, $0.1 million decommissioning and other charges; Plastics Solutions was allocated $0.2 million of accelerated depreciation, $(0.1) million employee termination benefits, $0.6 million of contract termination costs, $0.1 million decommissioning and other charges; and Polystyrene was allocated $0.6 million of accelerated depreciation, $(0.1) million employee termination benefits, $1.5 million of contract termination costs, $0.3 million decommissioning and other charges.

Refer to Note 13 for further information regarding the asset retirement obligation. The following table provides a

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roll forward of the other liability balances associated with the Company’s restructuring activities as of March 31, 2024. Employee termination benefits and contract termination charges are primarily recorded within “Accrued expenses and other current liabilities” in the condensed consolidated balance sheets.

	Balance at						Balance at
	December 31, 2023		Expenses		Deductions(1)		March 31, 2024
Employee termination benefits	$	16.7	$	(0.4)	$	(4.2)	$	12.1
Contract terminations		—		5.5		(5.5)		—
Decommissioning and other		—		2.9		(2.9)		—
Total	$	16.7	$	8.0	$	(12.6)	$	12.1

(1) Primarily includes payments made against the existing accrual, as well as immaterial impacts of foreign currency remeasurement.

NOTE 5—INCOME TAXES

	Three Months Ended
	March 31,
	2024			2023
Effective income tax rate		(7.7)	%		25.4	%

Provision for income taxes for the three months ended March 31, 2024 totaled $5.4 million, resulting in an effective tax rate of (7.7)%. Benefit from income taxes for the three months ended March 31, 2023 totaled $16.7 million, resulting in an effective tax rate of 25.4%.

The most significant driver of the decrease in the effective income tax rate for the three months ended March 31, 2024 compared to the prior year was the increase in losses not anticipated to provide a tax benefit, due to the increase in valuation allowances primarily in the United States and Switzerland.

In determining the need for a valuation allowance, the Company weighs both positive and negative evidence in the various jurisdictions in which it operates to determine whether sufficient future taxable income will be generated to permit use of the existing deferred tax assets. Based on cumulative earnings in the Company’s China subsidiary during the prior three years, as well as other positive evidence, the Company believes it is more likely than not that the net deferred tax assets in the Company’s China subsidiary will be realized as of March 31, 2024. However, given the Company’s recent losses, the Company will continue to evaluate positive and negative evidence over the next 12 months, that could result in sufficient objective negative evidence for the Company to reach a conclusion that a partial or full valuation allowance against the net deferred tax assets will be needed. A partial or full valuation allowance would result in the material reduction of deferred tax assets and a corresponding increase to income tax expense in the period the valuation allowance is recorded. The exact timing and amount of the valuation allowance are subject to change on the basis of the losses sustained in China in the current year and forecasted future earnings, as well as other evidence. The Company’s China Subsidiary has $13.5 million of net deferred tax assets as of March 31, 2024.

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NOTE 6—EARNINGS PER SHARE

Basic earnings per ordinary share (“basic EPS”) is computed by dividing net income available to ordinary shareholders by the weighted average number of the Company’s ordinary shares outstanding for the applicable period. Diluted earnings per ordinary share (“diluted EPS”) is calculated using net income available to ordinary shareholders divided by diluted weighted average ordinary shares outstanding during each period, which includes unvested RSUs, option awards, and PSUs. Diluted EPS considers the impact of potentially dilutive securities except in periods in which there is a loss from continuing operations because the inclusion of the potential ordinary shares would have an anti-dilutive effect.

The following table presents basic EPS and diluted EPS for the three months ended March 31, 2024 and 2023.

	Three Months Ended
	March 31,
(in millions, except per share data)	2024		2023
Earnings:
Net loss	$	(75.5)	$	(48.9)
Shares:
Weighted average ordinary shares outstanding		35.3		35.0
Dilutive effect of RSUs, option awards, and PSUs(1)		—		—
Diluted weighted average ordinary shares outstanding		35.3		35.0
Loss per share:
Loss per share‒basic	$	(2.14)	$	(1.40)
Loss per share‒diluted	$	(2.14)	$	(1.40)

(1) Refer to Note 15 for discussion of RSUs, option awards, and PSUs granted to certain Company directors and employees. As the Company recorded a net loss from continuing operations for the three months ended March 31, 2024 and March 31, 2023, potential shares related to equity-based awards have been excluded from the calculation of diluted EPS, as doing so would be anti-dilutive.

NOTE 7—INVENTORIES

Inventories consisted of the following:

	March 31,		December 31,
	2024		2023
Finished goods	$	190.2	$	162.4
Raw materials and semi-finished goods		199.4		200.9
Supplies		41.6		41.4
Total	$	431.2	$	404.7

NOTE 8—INVESTMENTS IN UNCONSOLIDATED AFFILIATES

The Company maintains an investment in an unconsolidated affiliate, Americas Styrenics LLC (“Americas Styrenics,” a styrene and polystyrene joint venture with Chevron Phillips Chemical Company LP), which is accounted for using the equity method. The results of Americas Styrenics are included within its separate reporting segment.

Americas Styrenics is a privately held company; therefore, a quoted market price for its equity interests is not available. The summarized financial information of the Company’s unconsolidated affiliate is shown below.

	Three Months Ended
	March 31,
	2024		2023
Sales	$	386.0	$	443.3
Gross profit	$	11.6	$	52.9
Net income (loss)	$	(3.7)	$	37.8

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As of March 31, 2024 and December 31, 2023, the Company’s investment in Americas Styrenics was $258.4 million and $252.2 million, respectively, which was $12.6 million and $4.8 million greater than the Company’s 50% share of the underlying net assets of Americas Styrenics, respectively. This amount represents the difference between the book value of assets held by the joint venture and the Company’s 50% share of the total recorded value of the joint venture’s assets, inclusive of certain adjustments to conform with the Company’s accounting policies. This difference is being amortized over a weighted average remaining useful life of approximately 2.6 years as of March 31, 2024. The Company received dividends of $0.0 million and $20.0 million from Americas Styrenics during the three months ended March 31, 2024 and 2023, respectively.

NOTE 9—GOODWILL

The following table shows changes in the carrying amount of goodwill, by segment, from December 31, 2023 to March 31, 2024:

	Engineered		Latex		Plastics				Americas
	Materials		Binders		Solutions		Polystyrene		Styrenics		Total
Balance at December 31, 2023	$	—	$	15.4	$	44.0	$	4.4	$	—	$	63.8
Foreign currency impact		—		(0.4)		(1.0)		(0.1)		—		(1.5)
Balance at March 31, 2024	$	—	$	15.0	$	43.0	$	4.3	$	—	$	62.3

As of March 31, 2024 and December 31, 2023, the reported balance of goodwill included accumulated impairment losses of $646.1 million in the Engineered Materials segment.

NOTE 10—LONG TERM DEBT & AVAILABLE FACILITIES

Refer to the Annual Report for definitions of capitalized terms not included herein and further background on the Company’s debt structure discussed below. The Company was in compliance with all debt related covenants as of March 31, 2024 and December 31, 2023.

As of March 31, 2024 and December 31, 2023, debt consisted of the following:

			March 31, 2024						December 31, 2023
	Interest Rate as of March 31, 2024	Maturity Date	Carrying Amount		Unamortized Deferred Financing Fees (1)		Total Debt, Less Unamortized Deferred Financing Fees		Carrying Amount		Unamortized Deferred Financing Fees (1)		Total Debt, Less Unamortized Deferred Financing Fees
2029 Senior Notes	5.125%	April 2029	$	447.0	$	(10.7)	$	436.3	$	447.0	$	(11.1)	$	435.9
2025 Senior Notes (2)	5.375%	September 2025		115.0		(0.5)		114.5		115.0		(0.6)		114.4
Senior Credit Facility
2028 Term Loan B	8.105%	May 2028		727.2		(11.2)		716.0		728.9		(11.8)		717.1
2026 Revolving Facility (3)	Various	May 2026		—		—		—		—		—		—
2028 Refinance Term Loans (2)	13.823%	May 2028		1,045.2		(21.2)		1,024.0		1,046.5		(22.6)		1,023.9
Accounts Receivable Securitization Facility (4)	Various	November 2025		—		—		—		—		—		—
Other indebtedness	Various	Various		7.0		—		7.0		7.2		—		7.2
Total debt			$	2,341.4	$	(43.6)	$	2,297.8	$	2,344.6	$	(46.1)	$	2,298.5
Less: current portion(5)								(21.1)						(20.9)
Total long-term debt, net of unamortized deferred financing fees							$	2,276.7					$	2,277.6

(1) This caption does not include deferred financing fees related to the Company’s revolving facilities, which are included within “Deferred charges and other assets” on the condensed consolidated balance sheets.

(2) The 2025 Senior Notes were partially repaid on September 8, 2023 using the proceeds of the 2028 Refinance Term Loans.

(3) As of March 31, 2024, under the 2026 Revolving Facility, the Company had a capacity of $375.0 million and $20.8

15

million outstanding letters of credit. As of March 31, 2024, the Company had funds available for borrowing of $101.7 million (net of the applicable $10.8 million outstanding letters of credit as defined in the secured credit agreement), which reflects the borrowing limit imposed by the springing covenant. The springing covenant applies when 30% or more of the 2026 Revolving Facility’s capacity is drawn which then requires the Company to meet a first lien net leverage ratio (as defined in the secured credit agreement) not to exceed 3.50x at the end of each financial quarter. As of March 31, 2024, the first lien net leverage ratio was 6.96x and the outstanding borrowings did not exceed the 30% threshold. Additionally, the Company is required to pay a quarterly commitment fee in respect of any unused commitments under this facility equal to 0.375% per annum.

(4) As of March 31, 2024, this facility had a borrowing capacity of $150.0 million, and the Company had approximately $150.0 million of accounts receivable available to support this facility, based on the pool of eligible accounts receivable.

(5) The current portion of long-term debt was primarily related to $18.3 million of the scheduled future principal payments on both the 2028 Term Loan B and the 2028 Refinance Term Loans as of March 31, 2024 and December 31, 2023.

The 2028 Refinance Credit Agreement requires the Company to comply with customary affirmative, negative and financial covenants, and contains events of default including (i) relating to a change of control or (ii) failure to maintain at least $100.0 million of Liquidity at the end of any calendar month, and (iii) a cross default to the Credit Agreement. If an event of default occurs, the Term Lenders will be entitled to take various actions, including the acceleration of amounts due under the 2028 Refinance Term Loans. Liquidity is defined under the 2028 Refinance Credit Agreement as a combination of cash and cash equivalents held at certain of the Company’s restricted subsidiaries as well as the funds available for borrowing under both the 2026 Revolving Facility and the Accounts Receivable Securitization Facility, subject to certain restrictions outlined in the 2028 Refinance Credit Agreement.

As of March 31, 2024, the Company was in compliance with all debt covenant requirements under the 2028 Refinance Credit Agreement and the Credit Agreement. The Company had Liquidity of $415.6 million, comprised of $163.8 million of cash and cash equivalents and approximately $251.7 million of funds available for borrowing under both the 2026 Revolving Facility and the Accounts Receivable Securitization Facility, $101.7 million and $150.0 million respectively.

We believe funds provided by operations, our cash and cash equivalent balances, coupled with borrowings available under our 2026 Revolving Facility and our Accounts Receivable Securitization Facility, will be adequate to meet necessary operating and capital expenditures for at least the next twelve months in the current operating environment.

The Company’s ability to repay the 2025 Senior Notes, which mature in September 2025 is also dependent on several factors, including the company’s ability to achieve its forecast cash flows and its ability to maintain minimum liquidity requirements under its related covenants. If the Company is unable to achieve its forecasts, maintain minimum liquidity covenants, or refinance, it could have a material adverse impact on our access to liquidity, results of operation and financial condition.

Accounts Receivable Securitization Facility

The Company has maintained an accounts receivable securitization facility (the “A/R Facility”) since 2010 for the securitization of trade receivables originated by certain of the Company’s Swiss, German, Dutch and U.S. subsidiaries. The A/R Facility is funded through the sale of commercial paper by a special purpose finance entity, the proceeds of which fund the purchase of trade receivables from the Trinseo subsidiaries. Collection accounts related to the trade receivables are pledged to the special purpose entity, which holds a first priority perfected security interest in such accounts and, as a

16

result, will not be available to the creditors of the Company or its other subsidiaries. The obligations of the Trinseo subsidiaries are also guaranteed by the Company’s subsidiary Trinseo Holding S.à r.l.

On March 28, 2024, the Company amended the A/R Facility to extend its maturity date to November 2025. As amended, the A/R Facility incurs fixed interest charges of 1.65% on outstanding borrowings plus variable commercial paper rates until November 18, 2024, at which time the fixed interest charges will increase to 3.5%. The A/R Facility also incurs fixed charges of 0.80% on available, but undrawn commitments and borrowing limit remains at $150.0 million. The A/R Facility contains standard representations, warranties and covenants, as well as standard termination or perfection events including those relating to (i) insolvency of the Company or certain of its subsidiaries, (ii) cross acceleration, and (iii) failure to maintain at least $250.0 million of liquidity after May 25, 2025. There were $0.5 million of fees incurred in connection with amending the facility which were capitalized and recorded within “Deferred charges and other assets” on the consolidated balance sheet and are being amortized over the remaining term of the facility using the straight-line method.

NOTE 11—FINANCIAL INSTRUMENTS AND DERIVATIVES

The Company’s ongoing business operations expose it to various risks, including fluctuating foreign exchange rates, interest rate risk, and commodity price risk, in particular natural gas. To manage these risks, the Company periodically enters into derivative financial instruments, such as foreign exchange forward contracts, interest rate swap agreements, and commodity swap agreements, forward contracts, or options. The Company does not hold or enter into financial instruments for trading or speculative purposes. All derivatives are recorded on the condensed consolidated balance sheets at fair value.

Foreign Exchange Forward Contracts

Certain subsidiaries have assets and liabilities denominated in currencies other than their respective functional currencies, which creates foreign exchange risk. The Company’s principal strategy in managing its exposure to changes in foreign currency exchange rates is to naturally hedge the foreign currency-denominated liabilities on its balance sheet against corresponding assets of the same currency, such that any changes in liabilities due to fluctuations in exchange rates are offset by changes in their corresponding foreign currency assets. In order to further reduce this exposure, the Company also uses foreign exchange forward contracts to economically hedge the impact of the variability in exchange rates on assets and liabilities denominated in certain foreign currencies. These derivative contracts are not designated for hedge accounting treatment and as a result, any mark-to-market fluctuations are recognized currently at each reporting date within loss from continuing operations.

As of March 31, 2024, the Company had open foreign exchange forward contracts with a notional U.S. dollar equivalent absolute value of $347.5 million. The following table displays the notional amounts of the most significant net foreign exchange hedge positions outstanding as of March 31, 2024:

Buy / (Sell)	March 31, 2024
Euro	$	(276.6)
Chinese Yuan	$	(21.7)
South Korean Won	$	(17.9)
Swiss Franc	$	12.9
Indonesian Rupiah	$	(5.9)

Open foreign exchange forward contracts as of March 31, 2024 had maturities occurring over a period of two months.

Foreign Exchange Cash Flow Hedges

From time-to-time, the Company also enters into forward contracts, as deemed appropriate, with the objective of managing the currency risk associated with forecasted U.S. dollar-denominated raw materials purchases by one of its subsidiaries whose functional currency is the euro. By entering into these forward contracts, which are designated as cash flow hedges, the Company buys a designated amount of U.S. dollars and sells euros at the prevailing market rate to mitigate the risk associated with the fluctuations in the euro-to-U.S. dollar foreign currency exchange rates. The qualifying hedge contracts are marked-to-market at each reporting date and any unrealized gains or losses are included in

17

Accumulated Other Comprehensive Income (“AOCI”) to the extent effective, and reclassified to cost of sales in the period during which the transaction affects earnings or it becomes probable that the forecasted transaction will not occur.

The Company had no open foreign exchange cash flow hedges as of March 31, 2024.

Commodity Cash Flow Hedges & Commodity Economic Hedges

The Company purchases certain commodities, primarily natural gas, to operate facilities and generate heat and steam for various manufacturing processes, which purchases are subject to price volatility. In order to manage the risk of price fluctuations associated with these commodity purchases, as deemed appropriate, the Company may enter into commodity swaps, forward contracts, or options. As of March 31, 2024, the Company had open commodity swap agreements, which effectively convert a portion of its natural gas costs into a fixed rate obligation. These commodity derivatives are designated as cash flow hedges, and as such, the contracts are marked-to-market at each reporting date and any unrealized gains or losses are included in AOCI to the extent effective, and reclassified to cost of sales in the period during which the transaction affects earnings or it becomes probable that the forecasted transaction will not occur.

Open commodity cash flow hedges as of March 31, 2024 had maturities occurring over a period of 9 months and had a notional value of approximately 462 thousand megawatt hours of natural gas purchases.

The Company may also enter into certain commodity swap agreements to economically hedge the impact of these price fluctuations, which are not designated for hedge accounting treatment. Open commodity economic hedges as of March 31, 2024 had maturities occurring over a period of 12 months and had a notional value of approximately 339 thousand megawatt hours of natural gas purchases.

Summary of Derivative Instruments

The following table presents the effect of the Company’s derivative instruments, including those not designated for hedge accounting treatment, on the condensed consolidated statements of operations for the three months ended March 31, 2024 and 2023:

	Location and Amount of Gain (Loss) Recognized in Statements of Operations
	Three Months Ended				Three Months Ended
	March 31, 2024				March 31, 2023
	Cost of sales		Other (expense) income, net		Cost of sales		Other (expense) income, net
Total amount of income and (expense) line items presented in the statements of operations in which the effects of derivative instruments are recorded	$	(843.4)	$	(3.8)	$	(959.1)	$	2.9
The effects of cash flow hedge instruments:
Commodity cash flow hedges
Amount of loss reclassified from AOCI into income	$	(4.8)	$	—	$	(6.4)	$	—
The effects of derivatives not designated as hedge instruments:
Foreign exchange forward contracts
Amount of gain (loss) recognized in income	$	—	$	6.5	$	—	$	(7.8)
Commodity economic hedges
Amount of loss recognized in income	$	(1.6)	$	—	$	(12.4)	$	—

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The following table presents the effect of cash flow hedge accounting on AOCI for the three months ended March 31, 2024 and 2023:

`	Gain (Loss) Recognized in AOCI on Balance Sheet
	Three Months Ended
	March 31,
	2024		2023
Designated as Cash Flow Hedges
Commodity cash flow hedges	$	2.7	$	(9.9)
Total	$	2.7	$	(9.9)

	Gain (Loss) Recognized in Other expense (income), net in Statement of Operations
	Three Months Ended
	March 31,
	2024		2023
Settlements and changes in the fair value of forward contracts (not designated as hedges)	$	6.5	$	(7.8)
Remeasurement of foreign currency-denominated assets and liabilities		(8.6)		10.5
Total	$	(2.1)	$	2.7

The Company expects to reclassify in the next twelve months an approximate $9.6 million net loss from AOCI into earnings related to the Company’s outstanding commodity cash flow hedges as of March 31, 2024, based on current commodity price indices.

The following tables summarize the gross and net unrealized gains and losses, as well as the balance sheet classification, of outstanding derivatives recorded in the condensed consolidated balance sheets:

	March 31, 2024
	Foreign
	Exchange		Commodity		Commodity
Balance Sheet	Forward		Economic		Cash Flow
Classification	Contracts		Hedges		Hedges		Total
Asset Derivatives:
Accounts receivable, net of allowance	$	1.2	$	—	$	—	$	1.2
Gross derivative asset position		1.2		—		—		1.2
Less: Counterparty netting		(0.5)		—		—		(0.5)
Net derivative asset position	$	0.7	$	—	$	—	$	0.7
Liability Derivatives:
Accounts payable	$	(0.7)	$	(6.0)	$	(9.6)	$	(16.3)
Gross derivative liability position		(0.7)		(6.0)		(9.6)		(16.3)
Less: Counterparty netting		0.5		—		—		0.5
Net derivative liability position	$	(0.2)	$	(6.0)	$	(9.6)	$	(15.8)
Total net derivative position	$	0.5	$	(6.0)	$	(9.6)	$	(15.1)

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	December 31, 2023
	Foreign
	Exchange		Commodity		Commodity
Balance Sheet	Forward		Economic		Cash Flow
Classification	Contracts		Hedges		Hedges		Total
Asset Derivatives:
Accounts receivable, net of allowance	$	0.3	$	—	$	—	$	0.3
Gross derivative asset position		0.3		—		—		0.3
Less: Counterparty netting		(0.3)		—		—		(0.3)
Net derivative asset position	$	—	$	—	$	—	$	—
Liability Derivatives:
Accounts payable	$	(4.8)	$	(7.2)	$	(13.7)	$	(25.7)
Other noncurrent obligations		—		(0.9)		(0.7)		(1.6)
Gross derivative liability position		(4.8)		(8.1)		(14.4)		(27.3)
Less: Counterparty netting		0.3		—		—		0.3
Net derivative liability position	$	(4.5)	$	(8.1)	$	(14.4)	$	(27.0)
Total net derivative position	$	(4.5)	$	(8.1)	$	(14.4)	$	(27.0)

Forward contracts, interest rate swaps, commodity forward contracts, swaps, or options, and cross currency swaps are entered into with a limited number of counterparties, each of which allows for net settlement of all contracts through a single payment in a single currency in the event of a default on or termination of any one contract. As such, in accordance with the Company’s accounting policy, these derivative instruments are recorded on a net basis by counterparty within the condensed consolidated balance sheets.

Refer to Notes 12 and 17 of the condensed consolidated financial statements for further information regarding the fair value of the Company’s derivative instruments and the related changes in AOCI.

NOTE 12—FAIR VALUE MEASUREMENTS

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Assets and liabilities measured at fair value are classified using the following hierarchy, which is based upon the transparency of inputs to the valuation as of the measurement date.

Level 1—Valuation is based upon quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2—Valuation is based upon quoted prices for similar assets and liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument.

Level 3—Valuation is based upon other unobservable inputs that are significant to the fair value measurement.

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The following table summarizes the basis used to measure certain assets and liabilities at fair value on a recurring basis in the condensed consolidated balance sheets as of March 31, 2024 and December 31, 2023:

	March 31, 2024
	Quoted Prices in Active Markets for Identical Items		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets (Liabilities) at Fair Value	(Level 1)		(Level 2)		(Level 3)		Total
Foreign exchange forward contracts—Assets	$	—	$	0.7	$	—	$	0.7
Foreign exchange forward contracts—(Liabilities)		—		(0.2)		—		(0.2)
Commodity economic hedges—(Liabilities)		—		(6.0)		—		(6.0)
Commodity cash flow hedges—(Liabilities)		—		(9.6)		—		(9.6)
Total fair value	$	—	$	(15.1)	$	—	$	(15.1)

	December 31, 2023
	Quoted Prices in Active Markets for Identical Items		Significant Other Observable Inputs		Significant Unobservable Inputs
Liabilities at Fair Value	(Level 1)		(Level 2)		(Level 3)		Total
Foreign exchange forward contracts—(Liabilities)	$	—	$	(4.5)	$	—	$	(4.5)
Commodity economic hedges—(Liabilities)		—		(8.1)		—		(8.1)
Commodity cash flow hedges—(Liabilities)		—		(14.4)		—		(14.4)
Total fair value	$	—	$	(27.0)	$	—	$	(27.0)

The Company uses an income approach to value its derivative instruments, utilizing discounted cash flow techniques, considering the terms of the contract and observable market information available as of the reporting date, such as interest rate yield curves and currency spot and forward rates. Significant inputs to the valuation for these derivative instruments are obtained from broker quotations or from listed or over-the-counter market data, and are classified as Level 2 in the fair value hierarchy.

Nonrecurring Fair Value Measurements

The Company measured certain financial assets at fair value on a nonrecurring basis during the year ended December 31, 2023, which were still held as of March 31, 2024. These financial assets represent the Company’s styrene monomer assets in Boehlen, Germany, which it continued to operate until the fourth quarter of 2022 when the Company decided to close this plant in connection with the asset restructuring plan. Refer to Note 4 for further information. These assets were measured at fair value using underlying fixed asset records in conjunction with the use of industry experience and available market data, which are classified as Level 3 significant unobservable inputs in the fair value hierarchy. As of March 31, 2024 and December 31, 2023, the value of the Boehlen styrene monomer assets are recorded at $3.2 and $3.2 million, respectively, within the Company’s condensed consolidated balance sheets herein.

There were no other financial assets or liabilities measured at fair value on a nonrecurring basis as of December 31, 2023.

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Fair Value of Debt Instruments

The following table presents the estimated fair value of the Company’s outstanding debt not carried at fair value as of March 31, 2024 and December 31, 2023:

	As of		As of
	March 31, 2024		December 31, 2023
2029 Senior Notes	$	146.7	$	180.4
2025 Senior Notes		92.8		98.5
2028 Term Loan B		539.9		564.9
2028 Refinance Term Loans		1,091.7		1,087.1
Total fair value	$	1,871.1	$	1,930.9

The fair value of the Company’s debt facilities above (each Level 2 securities) is determined using over-the-counter market quotes and benchmark yields received from independent vendors. The fair value amount presented reflect the Company’s carrying value of debt, net of original issuance discount.

There were no other significant financial instruments outstanding as of March 31, 2024 and December 31, 2023.

NOTE 13—COMMITMENTS AND CONTINGENCIES

Environmental Matters

Accruals for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated based on current law, existing technologies and other information. Pursuant to the terms of the agreement associated with the Company’s formation, the pre-closing environmental liabilities were retained by Dow, and Dow agreed, subject to temporal, monetary, and other limitations to indemnify the Company from and against environmental liabilities incurred or relating to the predecessor periods. Other than certain immaterial environmental liabilities assumed as part of the PMMA Acquisition and the Aristech Surfaces Acquisition, no material environmental claims have been asserted against the Company, and the Company does not have any material accrued obligations for any Superfund Sites. As of March 31, 2024 and December 31, 2023, the Company had $1.3 million of accrued obligations for environmental remediation or restoration costs, which were recorded at fair value within the opening balance sheets of the PMMA business and Aristech Surfaces during 2021.

On March 24, 2023, due to equipment failure at the Bristol, Pennsylvania facility, operated by our wholly-owned subsidiary, Altuglas LLC, an accidental release of a latex emulsion product occurred, which ultimately flowed into a local waterway (the “Bristol Spill”). We reported the event and cooperated closely with local, state, and federal authorities on the response activities. Water sampling conducted by the authorities did not detect site-related material in the waterway. See “Litigation Matters” below for information on environmental proceedings related to this incident. In the event of one or more adverse determinations related to this matter, it is possible that the ultimate liability resulting from this matter and the impact on the Company’s results of operations could be material.

Inherent uncertainties exist in the Company’s potential environmental liabilities primarily due to unknown conditions, whether future claims may fall outside the scope of the indemnity, changing governmental regulations and legal standards regarding liability, and evolving technologies for handling site remediation and restoration. In connection with the Company’s existing indemnification, the possibility is considered remote that environmental remediation costs will have a material adverse impact on the condensed consolidated financial statements over the next 12 months.

Purchase Commitments

In the normal course of business, the Company has certain raw material purchase contracts where it is required to purchase certain minimum volumes at current market prices. These commitments range from one to four years. In certain raw material purchase contracts, the Company has the right to purchase less than the required minimums and pay a liquidated damages fee, or, in case of a permanent plant shutdown, to terminate the contracts. In such cases, these obligations would be less than the annual commitment as disclosed in the Notes to Consolidated Financial Statements included in the Annual Report.

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Asset Retirement Obligations

The Company has built certain manufacturing facilities on leased land and is required to remove these facilities at the end of the corresponding contract term. Legal obligations for these demolition and decommissioning activities exist in connection with the retirement of these assets triggered upon closure of the facilities. In instances when the Company plans to continue operations at these facilities indefinitely, and therefore, a reasonable estimate of fair value cannot be determined, an asset retirement obligation is not recognized.

In connection with the Asset Restructuring Plan as described within Note 4, the Company concluded the Boehlen, Germany site no longer had an indeterminate life. Accordingly, during the fourth quarter of 2022, the Company recorded the fair value of an asset retirement obligation and a corresponding asset retirement cost, which was capitalized as part of the carrying amount of the related long-lived assets and depreciated over the asset’s shortened useful life. The asset retirement cost was fully depreciated as of March 31, 2024.

Change in asset retirement obligation
Balance at December 31, 2023	$	20.2
Obligations incurred and adjustments to estimated obligations		—
Settlements		(1.8)
Accretion expense		0.2
Currency translation adjustment		(0.5)
Balance at March 31, 2024	$	18.1

Accretion expense is included within “Selling, general and administrative expenses” in the condensed consolidated statement of operations. The current portion of the asset retirement obligation is recorded within “Accrued expenses and other current liabilities” and the long-term portion is recorded within “Other noncurrent obligations” in the condensed consolidated balance sheets. As of March 31, 2024 and December 31, 2023, the current portion was $8.8 million and $10.7 million, respectively, and the long-term portion was $9.3 million and $9.5 million, respectively.

Litigation Matters

From time to time, the Company may be subject to various legal claims and proceedings incidental to the normal conduct of business, relating to such matters as employees, product liability, antitrust/competition, past waste disposal practices and release of chemicals into the environment. While it is impossible at this time to determine with certainty the ultimate outcome of these routine claims, the Company does not believe that the ultimate resolution of these claims will have a material adverse effect on the Company’s results of operations, financial condition or cash flow. Legal costs, including those legal costs expected to be incurred in connection with a loss contingency, are expensed as incurred.

Legal Proceedings related to the Bristol Spill

(a) Timothy McGraw, Emily Cohen & Danielle Byrd v. Altuglas LLC and Trinseo LLC (United States District Court for the Eastern District of Pennsylvania)

On March 29, 2023, a putative class action complaint was filed which seeks to certify a class that could potentially include all persons and entities that reside in the area served by the Baxter Drinking Water Treatment Plant. The plaintiffs allege claims of breach of duty of care based on negligence as a result of the Bristol Spill, as well as other causes of action, and seek compensatory damages, restitution, or refund of damages, including actual, statutory, and punitive damages, as well as injunctive relief. On May 12, 2023, the Company filed notice to remove the case from Pennsylvania state court to United States District Court for the Eastern District of Pennsylvania, with immediate effect. On May 19, 2023, the Company also filed a motion to dismiss with the U.S. district court, on the grounds that the alleged harms do not fall within the parameters of the relevant public and private nuisance or negligence laws. On June 2, 2023, plaintiffs objected to federal jurisdiction and asked the court to remand the action to state court. On August 23, 2023, plaintiffs filed a voluntary dismissal of the federal complaint, which was granted on August 29, 2023. The parties signed a settlement agreement in December 2023, and on January 2, 2024, plaintiffs refiled their claim in the Court of Common Pleas of Philadelphia County and simultaneously submitted an unopposed motion for an order to preliminarily approve a class settlement. On March 15, 2024, an Order Preliminarily Approving Settlement was entered by the Court of Common Pleas, which

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provides for preliminary approval of the negotiated settlement, subject to a final approval hearing, defines members of the settlement class and appoints a settlement administrator to send notice to settlement class members. In the fourth quarter of 2023, the Company established an accrual for the estimated resolution of the class action complaint. Pursuant to the terms of the settlement agreement, $2.7 million was paid into escrow in April 2024, which amount was covered by the Company’s insurance coverage. The Order Preliminarily Approving Settlement provides for a Final Approval Hearing to be held on September 23, 2024.

(b) Environmental Proceedings

On March 25, 2023, the Company received a Notice of Federal Interest from the United States Coast Guard (“USCG”), identifying the Company as a “potentially responsible party” (“PRP”) related to the Bristol Spill. The Company also received a Notice of Federal Assumption and an Administrative Order, dated April 20, 2023 from the USCG, identifying the Company as a PRP related to the Bristol Spill. The USCG notices and order do not designate specific fines or penalties against the Company. In October 2023, the Pennsylvania Department of Environmental Protection (PADEP) notified the Company of its intent to impose penalties related to a Notice of Violation dated April 26, 2023 alleging water violations associated with the Spill. Discussions between the Company and PADEP are ongoing. In December 2023, the Company established an accrual for the estimated resolution of this matter, and such loss is not expected to be material to our business.

It is not possible at this time for the Company to estimate its ultimate liability pursuant to these matters or other potential administrative or criminal actions related to the Bristol Spill, whether a material loss to our business is probable or remote, or estimate a potential range of loss, if any.

Synthos Matter

On November 21, 2022, the Company received formal notice from the German Arbitration Institute that Synthos had initiated an arbitration dispute on October 14, 2022 against Trinseo and its following subsidiaries: Trinseo Deutschland GmbH, Trinseo Belgium BV, Trinseo Europe GmbH, and Trinseo Export GmbH, related to Synthos’ purchase of Trinseo’s Rubber Business in 2021.

Synthos and Trinseo are parties to an asset purchase agreement (“APA”) dated May 21, 2021, whereby Trinseo transferred its Rubber Business to Synthos, pending regulatory approval and other administrative pre-closing conditions, for an enterprise value of approximately $491.0 million. This transaction formally closed on December 1, 2021. Synthos claims that Trinseo did not properly disclose certain information including the natural gas pricing mechanism for the steam which is supplied by a third party to the Rubber Business. Synthos is seeking non-monetary restitution and monetary damages related to the spike of utility prices in Germany that commenced in the fall of 2021. On December 7, 2023, Synthos filed an adjusted motion with the German Arbitration Institute clarifying its claims for monetary damages. On April 26, 2024, Trinseo filed a statement of defense and counterclaim in response to Synthos’ adjusted motion.

The Company believes it has valid and prevailing defenses to Synthos’ claims and intends to vigorously defend itself against all allegations.

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NOTE 14—PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS

The components of net periodic benefit costs for all significant plans were as follows:

	Three Months Ended				Three Months Ended
	March 31,				March 31,
	Non-U.S. Defined Benefit Pension Plans				U.S. Defined Benefit Pension
	2024		2023		2024		2023
Net periodic benefit cost
Service cost	$	2.1	$	2.0	$	0.1	$	0.1
Interest cost		2.4		1.7		0.2		0.2
Expected return on plan assets		(1.0)		(0.2)		(0.2)		(0.1)
Amortization of prior service credit		(0.1)		(0.1)		—		—
Amortization of net gain		(0.3)		(0.8)		—		—
Net periodic benefit cost	$	3.1	$	2.6	$	0.1	$	0.2

The Company had less than $0.1 million of net periodic benefit costs for its other postretirement plans for the three months ended March 31, 2024 and 2023.

Service cost related to the Company’s defined benefit pension plans and other postretirement plans is included within “Cost of sales” and “Selling, general and administrative expenses,” whereas all other components of net periodic benefit cost are included within “Other expense (income), net” in the condensed consolidated statements of operations. As of March 31, 2024 and December 31, 2023, the Company’s benefit obligations included primarily in “Other noncurrent obligations” in the condensed consolidated balance sheets were $192.3 million and $197.0 million, respectively.

The Company made cash contributions and benefit payments to unfunded plans of approximately $2.5 million during the three months ended March 31, 2024. The Company expects to make additional cash contributions, including benefit payments to unfunded plans, of approximately $6.7 million to its defined benefit plans for the remainder of 2024.

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NOTE 15—SHARE-BASED COMPENSATION

Refer to the Annual Report for definitions of capitalized terms not included herein and further background on the Company’s share-based compensation programs included in the tables below.

The following table summarizes the Company’s share-based compensation expense for the three months ended March 31, 2024 and 2023, as well as unrecognized compensation cost as of March 31, 2024:

					As of
	Three Months Ended				March 31, 2024
	March 31,				Unrecognized		Weighted
	2024		2023		Compensation Cost		Average Years
RSUs	$	2.4	$	4.8	$	6.5	1.4
Options		0.8		2.6		1.1	1.2
PSUs		0.6		0.8		4.8	2.0
Restricted Cash Units ("RCUs")		2.1		—		3.0 (1)	1.9
Total share-based compensation expense	$	5.9	$	8.2

(1) Unrecognized Compensation Cost related to RCU awards as of March 31, 2024 is calculated using the stock price as of March 31, 2024.

The following table summarizes awards granted and the respective weighted average grant date fair value for the three months ended March 31, 2024:

	Three Months Ended
	March 31, 2024
	Awards Granted		Weighted Average Grant Date Fair Value per Award
RSUs		646,972	$	4.38
Options		319,407		2.48
PSUs		575,475		2.81
RCUs		1,074,119		4.85

Option Awards

The following are the weighted average assumptions used within the Black-Scholes pricing model for the Company’s option awards granted during the three months ended March 31, 2024:

	Three Months Ended
	March 31, 2024
Expected term (in years)	5.50
Expected volatility	64.12	%
Risk-free interest rate	4.28	%
Dividend yield	0.73	%

The expected volatility assumption is determined based on the historical volatility of the Company’s publicly traded ordinary shares. The expected term of option awards represents the period of time that option awards granted are expected to be outstanding. For the option awards granted during the three months ended March 31, 2024, the simplified method was used to calculate the expected term, given the Company’s limited historical exercise data. The risk-free interest rate for the periods within the expected term of option awards is based on the U.S. Treasury yield curve in effect at the time of grant. The dividend yield is estimated based on historical and expected dividend activity.

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Performance Share Units (PSUs)

The following are the weighted average assumptions used within the Monte Carlo valuation model for PSUs granted during the three months ended March 31, 2024:

		Three Months Ended
		March 31, 2024
Expected term (in years)		3.00
Expected volatility		65.40	%
Risk-free interest rate		4.40	%
Share price	$	4.39

Determining the fair value of PSUs requires considerable judgment, including estimating the expected volatility of the price of the Company’s ordinary shares, the correlation between the Company’s share price and that of its peer companies, and the expected rate of interest. The expected volatility for each grant is determined based on the historical volatility of the Company’s ordinary shares. The expected term of PSUs represents the length of the performance period. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for a duration equivalent to the performance period. The share price is the closing price of the Company’s ordinary shares on the grant date.

Restricted Cash Units (RCUs)

In the three months ending March 31, 2024, 1,074,119 restricted cash units ("RCUs") were awarded to certain employees and represent the right to receive a cash payment at the end of a vesting period, subject to the employee's continued employment. In general, RCUs vest in equal installments each year over 3 years. RCUs are cash-settled with the value of each vested RCU equal to the lower of the closing price per share of our common stock on the vesting date or a specified per share price cap. Certain awards are subject to a specified price floor. We determined that RCUs are in-substance liabilities accounted for as liability instruments in accordance with ASC 718, Compensation-Stock Compensation, due to this cash settlement feature. RCUs are remeasured based on the closing price per share of our common stock at the end of each reporting period. The liability associated with the RCUs is included in accrued expenses and other current liabilities in the condensed consolidated balance sheet. No RCU awards were vested or forfeited in the three months ending March 31, 2024.

NOTE 16—SEGMENTS AND GEOGRAPHIC INFORMATION

Effective January 1, 2024, the Company realigned its reporting segments to reflect the new model under which the business is managed, and results are reviewed by the chief executive officer, the Company’s chief operating decision maker. Following this change, the Company is operating under five segments, all of which remain unchanged from the Company’s prior six segment segmentation: Engineered Materials, Latex Binders, Plastics Solutions, Polystyrene, and Americas Styrenics.

The Company’s Feedstocks segment, which included the Company’s production and procurement of styrene monomer outside of North America, was eliminated as a result of the closures of the styrene plants located in Boehlen, Germany and Terneuzen, the Netherlands under an asset restructuring plan. Styrene monomer is a key raw material in many of the Company’s products, including polystyrene, styrene-butadiene latex (“SB latex”), and acrylonitrile-butadiene-styrene (“ABS”) resins. The Company no longer produces styrene, but instead purchases all of our styrene needs from third parties. Therefore, the information in the tables below has been adjusted to show the historical results of the Feedstocks segment within the segments that consumed styrene monomer in their end products, Latex Binders, Plastics Solutions and Polystyrene.

The Engineered Materials segment includes the Company’s compounds and blends products sold into higher growth and value applications, such as consumer electronics and medical, as well as soft thermoplastic elastomers (“TPEs”) products which are sold into markets such as footwear and automotive. Additionally, following the PMMA Acquisition and the Aristech Surfaces Acquisition in 2021, the Engineered Materials segment also includes PMMA and activated methyl methacrylates (“MMA”) products, which are sold into a variety of applications including automotive, building & construction, medical, consumer electronics, and wellness, among others. The Latex Binders segment produces SB latex and other latex polymers and binders, primarily for coated paper and packaging board, carpet and artificial turf backings, as well as a number of performance latex binders applications, such as adhesive, building and

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construction and the technical textile paper market. The Plastics Solutions segment contains the results of the ABS, styrene-acrylonitrile (“SAN”), and polycarbonate (“PC”) businesses, as well as compounds and blends for automotive and other applications. The Plastics Solutions segment also includes the results of Heathland, which was acquired in the first quarter of 2022. The Polystyrene segment includes a variety of general purpose polystyrenes (“GPPS”) and polystyrene that has been modified with polybutadiene rubber to increase its impact resistant properties (“HIPS”). Lastly, the Americas Styrenics segment consists solely of the operations of the Company’s 50%-owned joint venture, Americas Styrenics, a producer of both styrene monomer and polystyrene in North America.

The following table provides disclosure of the Company’s segment Adjusted EBITDA, which is used to measure segment operating performance and is defined below, for the three months ended March 31, 2024 and 2023. Asset and intersegment sales information by reporting segment are not regularly reviewed or included with the Company’s reporting to the chief operating decision maker. Therefore, this information has not been disclosed below. Refer to Note 3 for the Company’s net sales to external customers by segment for the three months ended March 31, 2024 and 2023.

	Engineered		Latex		Plastics				Americas		Total Segment
Three Months Ended (1)	Materials		Binders		Solutions		Polystyrene		Styrenics		Adjusted EBITDA
March 31, 2024	$	4.3	$	25.7	$	22.7	$	12.6	$	6.1	$	71.4
March 31, 2023	$	(11.7)	$	24.0	$	23.6	$	8.9	$	17.6	$	62.4

(1) The Company’s primary measure of segment operating performance is Adjusted EBITDA, which is defined as income from continuing operations before interest expense, net; provision for income taxes; depreciation and amortization expense; loss on extinguishment of long-term debt; asset impairment charges; gains or losses on the dispositions of businesses and assets; restructuring charges; acquisition related costs and benefits and other items. Segment Adjusted EBITDA is a key metric that is used by management to evaluate business performance in comparison to budgets, forecasts, and prior year financial results, providing a measure that management believes reflects core operating performance by removing the impact of transactions and events that would not be considered a part of core operations. Other companies in the industry may define segment Adjusted EBITDA differently than the Company, and as a result, it may be difficult to use segment Adjusted EBITDA, or similarly named financial measures, that other companies may use to compare the performance of those companies to the Company’s segment performance.

The reconciliation of income (loss) from continuing operations before income taxes to segment Adjusted EBITDA is as follows:

	Three Months Ended
	March 31,
	2024		2023
Loss before income taxes	$	(70.1)	$	(65.6)
Interest expense, net		63.0		38.3
Depreciation and amortization		45.0		56.0
Corporate Unallocated(2)		26.4		26.1
Adjusted EBITDA Addbacks(3)		7.1		7.6
Segment Adjusted EBITDA	$	71.4	$	62.4

(2) Corporate unallocated includes corporate overhead costs and certain other income and expenses.

(3) Adjusted EBITDA addbacks for the three months ended March 31, 2024 and 2023 are as follows:

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	Three Months Ended
	March 31,
	2024		2023
Net gain on disposition of businesses and assets	$	(3.6)	$	—
Restructuring and other charges (Note 4)		9.4		3.7
Asset impairment charges or write-offs (Note 12)		—		0.3
Other items (a)		1.3		3.6
Total Adjusted EBITDA Addbacks	$	7.1	$	7.6

(a) Other items for the three months ended March 31, 2024 and 2023 primarily relate to costs incurred in conjunction with certain of the Company’s strategic initiatives. Other items for the three months ended March 31, 2023 also relate to our transition to a new enterprise resource planning system.

NOTE 17—ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

The components of AOCI, net of income taxes, consisted of:

	Cumulative		Pension & Other
	Translation		Postretirement Benefit			Cash Flow
Three Months Ended March 31, 2024 and 2023	Adjustments		Plans, Net			Hedges, Net	Total
Balance as of December 31, 2023	$	(141.9)	$	17.1	$	(4.8)	$	(129.6)
Other comprehensive income (loss)		(11.8)		—		0.1		(11.7)
Amounts reclassified from AOCI to net income(1)		—		(0.4)		4.3		3.9
Balance as of March 31, 2024	$	(153.7)	$	16.7	$	(0.4)	$	(137.4)
Balance as of December 31, 2022	$	(151.2)	$	29.0	$	(9.1)	$	(131.3)
Other comprehensive income (loss)		10.5		—		(13.2)		(2.7)
Amounts reclassified from AOCI to net income (1)		—		0.3		5.8		6.1
Balance as of March 31, 2023	$	(140.7)	$	29.3	$	(16.5)	$	(127.9)

(1) The following is a summary of amounts reclassified from AOCI to net income (loss) for the three months ended March 31, 2024 and 2023:

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	Three Months Ended
	March 31,				Statements of Operations
AOCI Components	2024		2023		Classification
Cash flow hedging items
Commodity cash flow hedges	$	4.8	$	6.4	Cost of sales
Total before tax		4.8		6.4
Tax effect		(0.5)		(0.6)	Provision for (benefit from) income taxes
Total, net of tax	$	4.3	$	5.8
Amortization of pension and other postretirement benefit plan items
Prior service credit	$	(0.1)	$	0.1	(a)
Net actuarial (gain) loss		(0.4)		0.3	(a)
Total before tax		(0.5)		0.4
Tax effect		0.1		(0.1)	Provision for (benefit from) income taxes
Total, net of tax	$	(0.4)	$	0.3

(a) These AOCI components are included in the computation of net periodic benefit costs (see Note 14).

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

2024 Year-to-Date Highlights

During the three months ended March 31, 2024, Trinseo recognized net loss of $75.5 million and Adjusted EBITDA of $45.0 million. Continued persistent underlying demand weakness has been experienced across all reporting segments, especially in polystyrene and ABS, however, the impact to our operating performance was mitigated from lower costs, commercial actions and the asset restructuring initiatives that were announced in the fourth quarter of 2022 and the second half of 2023. In addition, sales volumes excluding styrene-related sales were the highest since the third quarter of 2022 and the first year-over-year increase since the first quarter of 2022. The Company continues to have access to capital resources through the refinancing of our debt structure during 2023, recent amendment of our A/R facility during first quarter 2024, and long-term debt maturities beginning in May 2028. Refer to the “Capital Resources and Liquidity” section below for further information.

Refer to the discussion below for further information and refer to “Non-GAAP Performance Measures” for discussion of our use of non-GAAP measures in evaluating our performance and a reconciliation of these measures. Other highlights for the year are described below.

Renewal of Accounts Receivable Securitization Facility

The Company has maintained an accounts receivable securitization facility (the “A/R Facility”) since 2010 for the securitization of trade receivables originated by certain of the Company’s Swiss, German, Dutch and U.S. subsidiaries.

On March 28, 2024, the Company extended the maturity date of the facility to November 2025. The A/R Facility borrowing limit remains at $150.0 million. As amended, the A/R Facility contains standard representations, warranties and covenants, as well as standard termination or perfection events including those relating to (i) insolvency of the Company or certain of its subsidiaries, (ii) cross acceleration, and (iii) failure to maintain at least $250.0 million of liquidity after May 25, 2025. Pursuant to the amendment, the A/R Facility incurs fixed interest charges of 1.65% on outstanding borrowings plus variable commercial paper or other benchmark rates until November 18, 2024, at which time the fixed interest charges will increase to 3.50%. Refer to Note 10 in the condensed consolidated financial statements for further details on these new financing arrangements.

Exploration for Divestiture of Americas Styrenics

In March 2024, the Company announced it commenced a sale process for the Company’s interest in Americas Styrenics, via the initiation of an ownership exit provision in the joint venture agreement, which is expected to lead to a definitive agreement in early 2025.

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Results of Operations

Results of Operations for the Three Months Ended March 31, 2024 and 2023

	Three Months Ended
	March 31,
(in millions)	2024		%		2023		%
Net sales	$	904.0	100	%	$	996.3	100	%
Cost of sales		843.4	93	%		959.1	96	%
Gross profit		60.6	7	%		37.2	4	%
Selling, general and administrative expenses		70.1	8	%		84.7	9	%
Equity in earnings of unconsolidated affiliate		6.2	1	%		17.6	2	%
Impairment and other charges		—	—	%		0.3	—	%
Operating loss		(3.3)	—	%		(30.2)	(3)	%
Interest expense, net		63.0	7	%		38.3	4	%
Other expense (income), net		3.8	—	%		(2.9)	—	%
Loss before income taxes		(70.1)	(7)	%		(65.6)	(7)	%
Provision for (benefit from) income taxes		5.4	1	%		(16.7)	(2)	%
Net loss	$	(75.5)	(8)	%	$	(48.9)	(5)	%

Three Months Ended – March 31, 2024 vs. March 31, 2023

Net Sales

Net sales decreased 9% year-over-year. Lower selling prices resulted in a 7% decrease from the pass through of lower raw material costs and pressure from weak polystyrene and acrylonitrile-butadiene-styrene (“ABS”) market conditions. Additionally, a decrease of 3% was related to lower sales volumes primarily from lower styrene-related sales following the closure of the Terneuzen, the Netherlands styrene facility. These decreases were partially offset by an increase of 1% due to favorable foreign exchange rate impacts.

Cost of Sales

The 12% decrease in cost of sales was primarily attributable to a 4% decrease in raw material and inventory costs, a 4% decrease from lower utilities, and a 2% decrease from lower fixed costs.

Gross Profit

The increase in gross profit of 73% was primarily due to prior year unfavorable impacts from natural gas hedges and fixed cost under absorption. See the segment discussion below for further information.

Selling, General and Administrative Expenses (SG&A)

The $14.6 million, or 17%, decrease in SG&A was primarily due to a decrease of $2.3 million in costs associated with the Company’s strategic initiatives, including the exploration of a potential divestiture of our styrenics business, a $4.1 million decrease in salary and wages expense, and a $5.1 million decrease in depreciation and amortization expense. Offsetting these decreased costs was a $5.7 million increase in restructuring costs, driven by the Asset Optimization and Corporate Restructuring plan approved in the third quarter of 2023 and the Asset Restructuring Plan approved in the fourth quarter of 2022.

Equity in Earnings of Unconsolidated Affiliate

The decrease in equity earnings from Americas Styrenics of $11.4 million was due to a planned turnaround at its largest styrene production facility in the current year.

Impairment and Other Charges

During the three months ended March 31, 2023, the Company recorded impairment charges of $0.3 million related to our Boehlen styrene monomer assets, as described within Note 12 in the condensed consolidated financial statements.

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Interest Expense, Net

The increase in interest expense, net of $24.7 million, or 64%, was primarily attributable to the year-over-year increase in market interest rates on our variable rate debt, specifically related to the 2028 Refinance Loans compared to the 2024 Term Loan B. Refer to Note 10 in the condensed consolidated financial statements for further information.

Other Expense (Income), Net

Other expense, net for the three months ended March 31, 2024 was $3.8 million, which included $1.0 million of expense related to the non-service cost components of net periodic benefit cost as well as foreign exchange transaction losses of $2.1 million. These net foreign exchange transaction losses included $8.6 million of losses primarily from the remeasurement of our euro-denominated payables due to the relative changes in rates between the U.S. dollar and the euro during the period, partially offset by $6.5 million or gains from our foreign exchange forward contracts.

Other income, net for the three months ended March 31, 2023 was $2.9 million, which was primarily driven by foreign exchange transaction gains of $2.7 million. These net foreign exchange transaction gains included $10.5 million of gains primarily from the remeasurement of our euro-denominated payables due to the relative changes in rates between the U.S. dollar and the euro during the period, partially offset by $7.8 million of losses from our foreign exchange forward contracts.

Provision for (Benefit from) Income Taxes

Provision for income taxes for the three months ended March 31, 2024 totaled $5.4 million, resulting in an effective tax rate of (7.7)%. Benefit from income taxes for the three months ended March 31, 2023 totaled $16.7 million, resulting in an effective tax rate of 25.4%.

The increase in provision for income taxes for the three months ended March 31, 2024 is primarily driven by the increase in losses not anticipated to provide a tax benefit, as we established additional valuation allowances in the United States and Switzerland for the period ended December 31, 2023.

Outlook

Positive earnings momentum from the end of the first quarter has continued into the second quarter and is expected to lead to a sequential profitability improvement following the first quarter planned major maintenance turnaround at Americas Styrenics, continued tightness in styrene and MMA markets, and the expected seasonally stronger period for many of our building and construction applications. The Company’s forecasted financial results also reflect the benefit of previously announced asset restructuring initiatives and management will continue to evaluate the potential for additional profitability actions.

The Company has access to capital resources and continues to focus on cash management and liquidity improvement actions to manage the continued impact of the challenging macroeconomic environment and higher interest costs on our business operations for the foreseeable future. The profitability improvement factors noted above, coupled with certain cash preservation initiatives that have been undertaken, such as closely managing working capital and a focus on required capital expenditures, will allow us to maintain adequate liquidity to position the Company to deliver sequentially improved results.

Selected Segment Information

The following sections describe net sales, Adjusted EBITDA, and Adjusted EBITDA margin by segment for the three months ended March 31, 2024 and 2023. Inter-segment sales have been eliminated. Refer to Note 16 in the condensed consolidated financial statements for further information on our segments, as well as for a detailed definition of Adjusted EBITDA and a reconciliation of income from continuing operations before income taxes to segment Adjusted EBITDA. Prior period segment amounts herein have been recast in conjunction with the Company’s segment realignment that occurred during the first quarter of 2024, as described in Note 16 of the condensed consolidated financial statements.

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Engineered Materials Segment

Our Engineered Materials segment consists of rigid thermoplastic compounds and blends products sold into high growth and high value applications in markets such as consumer electronics and medical, as well as soft thermoplastic elastomers (“TPEs”) products which are sold into markets such as footwear and automotive. The Engineered Materials segment also includes polymethyl methacrylates (“PMMA”) and activated methyl methacrylates (“MMA”) products, which are sold into a variety of applications including automotive, building & construction, medical, consumer electronics, and wellness, among others.

	Three Months Ended
	March 31,
($ in millions)	2024			2023			% Change
Net sales	$	189.2		$	206.2		(8)	%
Adjusted EBITDA	$	4.3		$	(11.7)		137	%
Adjusted EBITDA margin		2	%		(6)	%

Three Months Ended – March 31, 2024 vs. March 31, 2023

The 8% decrease in net sales was primarily attributable to a 12% decrease due to lower pricing from raw material pass-through. This decrease was offset by a 3% increase year-over-year due to higher sales volumes from PMMA resins and MMA.

The $16.0 million, or 137%, increase in Adjusted EBITDA was due to higher margins of $9.1 million, primarily related to MMA, including a $4.2 million favorable impact from lower natural gas hedge losses. Lower fixed costs from manufacturing cost under absorption in the prior year also resulted in a $9.8 million increase.

Latex Binders Segment

Our Latex Binders segment produces styrene-butadiene latex (“SB latex”) and other latex polymers and binders primarily for coated paper and packaging board, carpet and artificial turf backings, as well as a broad range of performance latex binders products, including SB latex, styrene-acrylate latex (“SA latex”), and vinylidene chloride latex for coatings, adhesives, sealants, and elastomers (“CASE”) applications.

	Three Months Ended
	March 31,
($ in millions)	2024			2023			% Change
Net sales	$	241.5		$	249.0		(3)	%
Adjusted EBITDA	$	25.7		$	24.0		7	%
Adjusted EBITDA margin		11	%		10	%

Three Months Ended – March 31, 2024 vs. March 31, 2023

The 3% decrease in net sales was primarily due to a 7% from lower price from the pass-through of lower raw material costs, partially offset by a 3% impact from higher volumes in paper and board applications.

The $1.7 million, or 7%, increase in Adjusted EBITDA was primarily due to a $2.6 million, or 11%, higher margins as the result of pricing actions in Europe and North America.

Plastics Solutions Segment

Our Plastics Solutions segment consists of a variety of compounds and blends, the majority of which are for automotive applications. The segment also includes our ABS, styrene-acrylonitrile (“SAN”), and polycarbonate (“PC”) businesses.

	Three Months Ended
	March 31,
($ in millions)	2024			2023			% Change
Net sales	$	265.7		$	300.3		(12)	%
Adjusted EBITDA	$	22.7		$	23.6		(4)	%
Adjusted EBITDA margin		9	%		8	%

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Three Months Ended – March 31, 2024 vs. March 31, 2023

Net sales decreased by 12% year-over-year, primarily due to an 8% decrease from lower pricing due to weaker market conditions in ABS. In addition, sales decreased 4% from lower volume in polycarbonate.

The $0.9 million, or 4%, decrease in Adjusted EBITDA was primarily due to a $0.4 million, or 2%, as lower ABS margin was mostly offset by a favorable net timing variance from increasing styrene cost during the quarter.

Polystyrene Segment

Our product offerings in our Polystyrene segment include a variety of general purpose polystyrenes (“GPPS”) and polystyrene that has been modified with polybutadiene rubber to increase its impact resistant properties (“HIPS”). These products provide customers with performance and aesthetics at a low cost across applications, including appliances, packaging, including food packaging and food service disposables, consumer electronics, and building and construction materials.

	Three Months Ended
	March 31,
($ in millions)	2024			2023			% Change
Net sales	$	207.6		$	240.8		(14)	%
Adjusted EBITDA	$	12.6		$	8.9		42	%
Adjusted EBITDA margin		6	%		4	%

Three Months Ended – March 31, 2024 vs. March 31, 2023

Net sales decreased by 14% year-over-year. Lower sales volumes due to due to lower styrene-related sales and, to a lesser extent, polystyrene sales led to a 11% decrease in net sales from the prior year. Also contributing to the overall decrease was a 3% decrease from lower pricing, primarily due to pressure from weaker market conditions in Europe.

The $3.7 million, or 42%, increase in Adjusted EBITDA was primarily due to a $4.4 million, or 49%, favorable net timing variance as well as $3.1 million, or 35%, lower fixed costs following the closure of the styrene production facility in Terneuzen, the Netherlands.

Americas Styrenics Segment

This segment consists solely of the equity earnings from our 50%-owned joint venture, Americas Styrenics, a producer of both styrene monomer and polystyrene in North America. Styrene monomer is a basic building block of plastics and a key input to many of the Company’s products, as well as a key raw material for the production of polystyrene. Major applications for the polystyrene products Americas Styrenics produces include appliances, food packaging, food service disposables, consumer electronics, and building and construction materials.

	Three Months Ended
	March 31,
($ in millions)	2024		2023		% Change
Adjusted EBITDA*	$	6.1	$	17.6	(65)	%

*The results of this segment are comprised entirely of earnings from Americas Styrenics, our equity method investment. As such, Adjusted EBITDA related to this segment is included within “Equity in earnings of unconsolidated affiliates” in the condensed consolidated statements of operations.

Three Months Ended – March 31, 2024 vs. March 31, 2023

The decrease in Adjusted EBITDA was mainly due to a planned turnaround at its largest styrene production facility in the current year.

Non-GAAP Performance Measures

We present Adjusted EBITDA as a non-GAAP financial performance measure, which we define as income from continuing operations before interest expense, net; provision for income taxes; depreciation and amortization expense; loss on extinguishment of long-term debt; asset impairment charges; gains or losses on the dispositions of businesses and

35

assets; restructuring charges; acquisition related costs, certain strategic initiatives and other items. In doing so, we are providing management, investors, and credit rating agencies with an indicator of our ongoing performance and business trends, removing the impact of transactions and events that we would not consider a part of our core operations.

There are limitations to using the financial performance measures such as Adjusted EBITDA. This performance measure is not intended to represent net income or other measures of financial performance. As such, it should not be used as an alternative to net income as an indicator of operating performance. Other companies in our industry may define Adjusted EBITDA differently than we do. As a result, it may be difficult to use this or similarly-named financial measures that other companies may use, to compare the performance of those companies to our performance. We compensate for these limitations by providing a reconciliation of this performance measure to our net income, which is determined in accordance with GAAP.

Adjusted EBITDA is calculated as follows for the three months ended March 31, 2024 and 2023:

	Three Months Ended
	March 31,
(in millions)	2024		2023
Net loss	$	(75.5)	$	(48.9)
Interest expense, net		63.0		38.3
Provision for (benefit from) income taxes		5.4		(16.7)
Depreciation and amortization		45.0		56.0
EBITDA(a)	$	37.9	$	28.7
Net gain on disposition of businesses and assets(b)		(3.6)		—
Restructuring and other charges(c)		9.4		3.7
Asset impairment charges or write-offs(d)		—		0.3
Other items(e)		1.3		3.6
Adjusted EBITDA	$	45.0	$	36.3

(a) EBITDA is a non-GAAP financial performance measure that we refer to in making operating decisions because we believe it provides our management as well as our investors and credit agencies with meaningful information regarding the Company’s operational performance. We believe the use of EBITDA as a metric assists our board of directors, management and investors in comparing our operating performance on a consistent basis. Other companies in our industry may define EBITDA differently than we do. As a result, it may be difficult to use EBITDA, or similarly-named financial measures that other companies may use, to compare the performance of those companies to our performance. We compensate for these limitations by providing reconciliations of our EBITDA results to our net income, which is determined in accordance with GAAP.

(b) Amounts for the three months ended March 31, 2024 primarily relate to the sale of the Belen, New Mexico and Brondeslev, Denmark manufacturing facilities. Refer to Note 4 in the condensed consolidated financial statements for further information.

(c) Amounts for the three months ended March 31, 2024 and 2023 primarily relate to charges incurred in connection with the Company’s various restructuring programs. Refer to Note 4 in the condensed consolidated financial statements for further information.

(d) Amounts for the three months ended March 31, 2023 primarily relate to the impairment of the Company’s styrene monomer assets in Boehlen, Germany, as described within Note 12 in the condensed consolidated financial statements.

(e) Other items for the three months ended March 31, 2024 and 2023 primarily relate to fees incurred in conjunction with certain of the Company’s strategic initiatives, including the potential divestiture of our styrenics business and our transition to a new enterprise resource planning system.

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Liquidity and Capital Resources

Cash Flows

The table below summarizes our primary sources and uses of cash for the three months ended March 31, 2024 and 2023. We have derived the summarized cash flow information from our unaudited financial statements.

	Three Months Ended
	March 31,
(in millions)	2024		2023
Net cash provided by (used in):
Operating activities	$	(66.2)	$	45.4
Investing activities		(11.0)		(21.8)
Financing activities		(9.2)		(20.5)
Effect of exchange rates on cash		(3.2)		2.3
Net change in cash, cash equivalents, and restricted cash	$	(89.6)	$	5.4

Operating Activities

Net cash used in operating activities during the three months ended March 31, 2024 totaled $66.2 million, which included $39.4 million of cash interest payments and was not offset by any dividends received from Americas Styrenics, mainly attributable to the impact from the planned turnaround at its largest styrene production facility in the current year. While the first quarter working capital increase was expected, it was higher than our typical seasonal working capital build due to significantly higher styrene costs.

Net cash provided by operating activities during the three months ended March 31, 2023 totaled $45.4 million, which included $35.5 million of cash interest payments and was partially offset by $20.0 million of dividends received from Americas Styrenics. Although operating results continued to be challenged by customer destocking and macroeconomic conditions, which resulted in reduced customer demand and negative earnings, there was a significant working capital release during the quarter. This working capital release was primarily a result of targeted inventory control actions and cash improvement initiatives.

Investing Activities

Net cash used in investing activities during the three months ended March 31, 2024 totaled $11.0 million, which was primarily attributable to capital expenditures of $15.7 million offset by proceeds from the sale of other assets of $4.7 million.

Net cash used in investing activities during the three months ended March 31, 2023 totaled $21.8 million, which was primarily attributable to capital expenditures.

Financing Activities

Net cash used in financing activities during the three months ended March 31, 2024 totaled $9.2 million. This activity was primarily due to $4.6 million in debt repayments, $0.6 million of dividends paid, and $3.7 million of net repayments of short-term borrowings. During the three months the Company drew and fully repaid $30.0 million in proceeds from the A/R Facility.

Net cash used in financing activities during the three months ended March 31, 2023 totaled $20.5 million. This activity was primarily due to $11.8 million of dividends paid, and $6.3 million in debt repayments.

Free Cash Flow

We use Free Cash Flow as a non-GAAP measure to evaluate and discuss the Company’s liquidity position and results. Free Cash Flow is defined as cash from operating activities, less capital expenditures. We believe that Free Cash Flow provides an indicator of the Company’s ongoing ability to generate cash through core operations, as it excludes the cash impacts of various financing transactions as well as cash flows from business combinations that are not considered organic in nature. We also believe that Free Cash Flow provides management and investors with useful analytical

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indicator of our ability to service our indebtedness, pay dividends (when declared), and meet our ongoing cash obligations.

Free Cash Flow is not intended to represent cash flows from operations as defined by GAAP, and therefore, should not be used as an alternative for that measure. Other companies in our industry may define Free Cash Flow differently than we do. As a result, it may be difficult to use this or similarly-named financial measures that other companies may use, to compare the liquidity and cash generation of those companies to our own. We compensate for these limitations by providing a reconciliation to cash provided by operating activities from continuing operations, which is determined in accordance with GAAP.

	Three Months Ended
	March 31,
(in millions)	2024		2023
Cash provided by (used in) operating activities	$	(66.2)	$	45.4
Capital expenditures		(15.7)		(21.8)
Free Cash Flow	$	(81.9)	$	23.6

Refer to the discussion above for significant impacts to cash provided by (used in) operating activities for the three months ended March 31, 2024 and 2023.

Capital Resources and Liquidity

We require cash principally for day-to-day operations, to finance capital investments and other initiatives, to purchase materials, to service our outstanding indebtedness, and to fund the return of capital to shareholders via dividend payments and ordinary share repurchases, when deemed appropriate. Our sources of liquidity include cash on hand, cash flow from operations from continuing operations, and amounts available under the Senior Credit Facility and the Accounts Receivable Securitization Facility (discussed further below).

The 2028 Refinance Credit Agreement requires the Company to comply with customary affirmative, negative and financial covenants, and contains events of default including (i) relating to a change of control or (ii) failure to maintain at least $100.0 million of Liquidity at the end of any calendar month, and (iii) a cross default to the Credit Agreement. If an event of default occurs, the Term Lenders will be entitled to take various actions, including the acceleration of amounts due under the 2028 Refinance Term Loans. Liquidity is defined under the 2028 Refinance Credit Agreement as a combination of cash and cash equivalents held at certain of the Company’s restricted subsidiaries as well as the funds available for borrowing under both the 2026 Revolving Facility and the Accounts Receivable Securitization Facility, subject to certain restrictions outlined in the 2028 Refinance Credit Agreement. As of March 31, 2024, the Company was in compliance with all debt covenant requirements under the 2028 Refinance Credit Agreement and the Credit Agreement.

As of March 31, 2024, the Company had Liquidity of $415.6 million, comprised of $163.8 million of cash and cash equivalents and approximately $251.7 million of funds available for borrowing under both the 2026 Revolving Facility and the Accounts Receivable Securitization Facility, $101.7 million and $150.0 million respectively. At March 31, 2024 and December 31, 2023, we had $2,341.4 million and $2,344.6 million, respectively, in outstanding indebtedness and $464.7 million and $521.5 million, respectively, in working capital. In addition, as of March 31, 2024 and December 31, 2023, we had $100.6 million and $161.4 million, respectively, of foreign cash and cash equivalents on our balance sheet, outside of Ireland, our country of domicile, all of which is readily convertible into other foreign currencies, including the U.S. dollar. Our intention is not to permanently reinvest our foreign cash and cash equivalents. Accordingly, we record deferred income tax liabilities related to the unremitted earnings of our subsidiaries.

The following table outlines our outstanding indebtedness as of March 31, 2024 and December 31, 2023 and the associated interest expense, including amortization of deferred financing fees and debt discounts. Effective interest rates for the borrowings included in the table below exclude the impact of deferred financing fee amortization, certain other fees charged to interest expense (such as fees for unused commitment fees during the period), and the impacts of derivatives designated as hedging instruments. For definitions of capitalized terms not included herein, refer to our Annual Report on Form 10-K (“Annual Report”).

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	As of and for the Three Months Ended						As of and for the Year Ended
	March 31, 2024						December 31, 2023
			Effective						Effective
			Interest		Interest				Interest		Interest
($ in millions)	Balance		Rate		Expense		Balance		Rate		Expense
2029 Senior Notes	$	447.0	5.1	%	$	6.2	$	447.0	5.1	%	$	24.8
2025 Senior Notes		115.0	5.4	%		1.6		115.0	5.4	%		21.4
Senior Credit Facility
2024 Term Loan B		—	—	%		—		—	—	%		34.1
2028 Term Loan B		727.2	8.1	%		15.8		728.9	8.2	%		59.9
2026 Revolving Facility		—	—	%		0.6		—	—	%		2.3
2028 Refinance Term Loans		1,045.2	13.8	%		39.9		1,046.5	13.8	%		50.4
Accounts Receivable Securitization Facility		—	7.1	%		0.4		—	—	%		1.3
Other indebtedness		7.0	5.3	%		0.1		7.2	6.5	%		0.4
Total	$	2,341.4			$	64.6	$	2,344.6			$	194.6

As of March 31, 2024, our Senior Credit Facility included the 2026 Revolving Facility, which is scheduled to mature in May 2026 and had a borrowing capacity of $375.0 million and $20.8 million outstanding letters of credit. The 2026 Revolving Facility contains a springing covenant which, if not met, limits our borrowing to 30% of the maximum available capacity under the 2026 Revolving Facility. This covenant requires the Company to meet a first lien net leverage ratio (as defined in our secured credit agreement) not to exceed 3.50x at the end of each financial quarter. As of March 31, 2024, the first lien net leverage ratio was 6.96x, and as such, the Company had $101.7 million of funds available for borrowing (net of $10.8 million outstanding letters of credit as defined in the secured credit agreement). Further, as of March 31, 2024, the Company is required to pay a quarterly commitment fee in respect of any unused commitments under the 2026 Revolving Facility equal to 0.375% per annum.

Also included in our Senior Credit Facility is our 2028 Term Loan B (with original principal of $750.0 million, maturing in May 2028), which requires scheduled quarterly payments in amounts equal to 0.25% of the original principal. The stated interest rate on our 2028 Term Loan B is SOFR plus 2.50% (subject to a 0.00% SOFR floor).

As of March 31 2024, our 2028 Refinance Term Loans (with original principal of $1,077.3 million, maturing in May 2028), issued under the 2028 Refinance Credit Agreement, have a stated interest rate plus 8.50% (subject to a 3.00% SOFR floor), and was issued at a 3.0% original issue discount.

During the year ended March 31, 2024, the Company made $2.7 million and $1.9 million of net principal payments related to the 2028 Refinance Term Loans and the 2028 Term Loan B, respectively, and as of March 31, 2024, the Company’s has an additional $18.3 million of scheduled future payments classified within current debt on consolidated balance sheet related to both the 2028 Refinance Term Loans and the 2028 Term Loan B.

As of March 31, 2024, our 2025 Senior Notes, as issued under the Indenture executed in 2017, include $115.0 million aggregate principal amount of 5.375% senior notes that mature on September 1, 2025. These Notes may be redeemed prior to their maturity at the option of the Company under certain circumstances at specific redemption prices.

As of March 31, 2024, our 2029 Senior Notes, as issued under the Indenture executed in 2021, include $500.0 million aggregate principal amount of 5.125% senior notes that mature on April 1, 2029. Interest on the 2029 Senior Notes is payable semi-annually on February 15 and August 15 of each year, which commenced on August 15, 2021. These Notes may be redeemed prior to their maturity at the option of the Company under certain circumstances at specific redemption prices.

We also continue to maintain our Accounts Receivable Securitization Facility. On March 28, 2024, the Company extended the maturity date of the facility to November 2025. The A/R Facility borrowing limit remains at $150.0 million. As amended, the A/R Facility contains standard representations, warranties and covenants, as well as standard termination or perfection events including those relating to (i) insolvency of the Company or certain of its subsidiaries, (ii) cross acceleration, and (iii) failure to maintain at least $250.0 million of liquidity after May 25, 2025. Pursuant to the amendment, the A/R Facility incurs fixed interest charges of 1.65% on outstanding borrowings plus variable commercial paper or other benchmark rates until November 18, 2024, at which time the fixed interest charges will increase to 3.50%. As of March 31, 2024, there were no amounts outstanding under this facility and the Company had approximately

39

$150.0 million of accounts receivable available to support this facility, based on the pool of eligible accounts receivable. Refer to Note 10 in the consolidated financial statements for further information on the facility.

Our ability to raise additional financing and our borrowing costs may be impacted by short- and long-term debt ratings assigned by independent rating agencies, which are based, in significant part, on our performance as measured by certain credit metrics such as interest coverage and leverage ratios.

We and our subsidiaries, affiliates or significant shareholders may from time to time seek to retire or purchase our outstanding debt through cash purchases in the open market, privately negotiated transactions, exchange transactions or otherwise. Such repurchases or exchanges, if any, will depend on prevailing market conditions, our liquidity requirements, contractual restrictions and other factors. The amounts involved may be material.

Trinseo Materials Operating S.C.A. and Trinseo Materials Finance, Inc. (the “Issuers” of our 2029 Senior Notes and 2025 Senior Notes and “Borrowers” under our Senior Credit Facility) are dependent upon the cash generation and receipt of distributions and dividends or other payments from our subsidiaries and joint venture in order to satisfy their debt obligations. There are no known significant restrictions by third parties on the ability of subsidiaries of the Company to disburse or dividend funds to the Issuers and the Borrowers in order to satisfy these obligations. However, as the Company’s subsidiaries are located in a variety of jurisdictions, the Company can give no assurances that our subsidiaries will not face transfer restrictions in the future due to regulatory or other reasons beyond our control.

The Senior Credit Facility and Indentures also limit the ability of the Borrowers and Issuers, respectively, to pay dividends or make other distributions to Trinseo PLC, which could then be used to make distributions to shareholders. During the three months ended March 31, 2024, the Company declared dividends of $0.01 per ordinary share, totaling $0.3 million, all of which was accrued as of March 31, 2024 and was paid in April 2024. These dividends are well within the available capacity under the terms of the restrictive covenants contained in the Senior Credit Facility and Indentures. Further, additional capacity continues to be available under the terms of these covenants to support expected future dividends to shareholders, should the Company continue to declare them.

We believe funds provided by operations, our cash and cash equivalent balances, coupled with borrowings available under our 2026 Revolving Facility and our Accounts Receivable Securitization Facility, will be adequate to meet necessary operating and capital expenditures for at least the next twelve months in the current operating environment.

The Company’s ability to meet our liquidity needs and to repay the 2025 Senior Notes, which mature in September 2025, is also dependent on several factors, including the company’s ability to achieve its forecast cash flows and its ability to maintain minimum liquidity requirements under its related covenants. If the Company is unable to achieve its forecasts, maintain minimum liquidity covenants, or refinance, it could have a material adverse impact on our access to liquidity, results of operation and financial condition.

Our ability to generate cash from operations to pay our indebtedness and meet other liquidity needs is subject to certain risks described herein and under Part I, Item 1A – Risk Factors of our Annual Report, as well as risk factors included in Part II, Item 1A herein. As of March 31, 2024, we were in compliance with all the covenants and default provisions under our debt agreements. Refer to our Annual Report for further information on the details of the covenant requirements.

Contractual Obligations and Commercial Commitments

There have been no material revisions outside the ordinary course of business to our contractual obligations as described within “Management’s Discussion and Analysis of Financial Condition and Results of Operations – Contractual Obligations and Commercial Commitments” within our Annual Report.

Critical Accounting Policies and Estimates

Our unaudited interim condensed consolidated financial statements are based on the selection and application of significant accounting policies. The preparation of unaudited interim condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and revenues and expenses at the date of and during the reporting period. Actual results could differ

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from those estimates. However, we are not currently aware of any reasonably likely events or circumstances that would result in materially different results.

We describe our significant accounting policies in Note 2, Basis of Presentation and Summary of Significant Accounting Policies, in the Notes to Consolidated Financial Statements included in our Annual Report, while we discuss our critical accounting policies and estimates in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” within our Annual Report. There have been no material revisions to the significant accounting policies or critical accounting policies and estimates as filed in our Annual Report.

Off-Balance Sheet Arrangements

We do not have any off-balance sheet arrangements.

Recent Accounting Pronouncements

We describe the impact of recent accounting pronouncements in Note 2 of our condensed consolidated financial statements, included elsewhere within this Quarterly Report.

Item 3. Quantitative and Qualitative Disclosures About Market Risk

As discussed in “Quantitative and Qualitative Disclosures About Market Risk” within our Annual Report, we are exposed to changes in interest rates and foreign currency exchange rates as well as changes in the prices of certain commodities that we use in production. There have been no material changes in our exposure to market risks from the information provided within our Annual Report.

Item 4. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

Our management is responsible for establishing and maintaining internal controls designed to provide reasonable assurance that information required to be disclosed by us in our reports that we file or submit under the Exchange Act (as defined in Rules 13a-15(e) and 15d-15(e) of the Securities Exchange Act of 1934, as amended) is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms, and that such information is accumulated and communicated to our management, with the participation of our Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosures. Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, evaluated the effectiveness of the Company’s disclosure controls and procedures as of March 31, 2024. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures as of the end of the period covered by this Quarterly Report were effective to provide the reasonable level of assurance described above.

Changes in Internal Control over Financial Reporting

There were no additional changes in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) of the Exchange Act) that occurred during the quarter ended March 31, 2024 that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

PART II — OTHER INFORMATION

Item 1. Legal Proceedings

From time to time we may be subject to various legal claims and proceedings incidental to the normal conduct of business, relating to such matters as product liability, antitrust, competition, waste disposal practices, release of chemicals into the environment and other matters that may arise in the ordinary course of our business. Regardless of the outcome, legal proceedings can have an adverse impact on us because of defense and settlement costs, diversion of management resources and other factors. For information regarding new matters and material developments in legal proceedings during the quarter ended March 31, 2024, see “Litigation Matters” in Note 13 to our condensed consolidated financial statements.

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Item 1A. Risk Factors

Our business faces various risks. Certain important factors may have a material adverse effect on our business prospects, financial condition and results of operations, and you should carefully consider them. Accordingly, in evaluating our business, we encourage you to consider the risk factors related to our ordinary shares as well those risk factors related to our business and industry which have been previously disclosed in Part 1, Item 1A of our Annual Report for the year ended December 31, 2023. Certain material updates to these risk factors are included below.

We encourage you to consider these risks, in their entirety, in addition to other information contained in or incorporated by reference into this Quarterly Report and our other public filings with the SEC. Other events that we do not currently anticipate or that we currently deem immaterial may also affect our business, prospects, financial condition and results of operations.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

(a) Recent sales of unregistered securities

None.

(b) Use of Proceeds from registered securities

None.

(c) Purchases of Equity Securities by the Issuer and Affiliated Purchasers

On September 2, 2022, the board of directors of the Company unanimously approved the authorization of a share repurchase program where the Company may repurchase up to $200.0 million of our ordinary shares, subject to certain parameters defined by the board of directors. Repurchases may be effected through open market purchases, 10b5-1 plans or by other means. The repurchase authorization expired after 18 months from the date of authorization. There were no share repurchases during the three months ended March 31, 2024.

Item 3. Defaults Upon Senior Securities

None.

Item 4. Mine Safety Disclosures

Not applicable.

Item 5. Other Information

None of the Company’s directors or officers adopted, modified, or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement during the Company’s fiscal quarter ended March 31, 2024.

Item 6. Exhibits

See Exhibit Index.

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EXHIBIT INDEX

Exhibit  No.	Description
3.1	Memorandum and Articles of Association of Trinseo PLC, as amended (incorporated herein by reference to Exhibit 3.1 to the Current Report on Form 8-K, filed on June 17, 2022).
4.1	Indenture among Trinseo Materials Operating S.C.A., Trinseo Materials Finance, Inc. and The Bank of New York Mellon, as Trustee, dated as of August 29, 2017 (incorporated herein by reference to Exhibit 4.1 to the Current Report on Form 8-K, filed September 5, 2017).
4.2	Indenture among Trinseo Materials Operating S.C.A., Trinseo Materials Finance, Inc. and The Bank of New York Mellon, as Trustee, dated as of March 24, 2021 (incorporated by reference to Exhibit 4.1 to the Current Report on Form 8-K filed March 24, 2021).
10.1*	Deed of Amendment, Restatement and Accession, dated March 28, 2024, entered into by and among Trinseo Europe GmbH, Trinseo Export GmbH, Trinseo Deutschland Anlagengesellschaft mbH, Trinseo Netherlands B.V., Altuglas LLC, Aristech Surfaces, LLC, Trinseo LLC, Trinseo U.S. Receivables Company SPV LLC, Styron Receivables Funding Designated Activity Company, Regency Assets Designated Activity Company, HSBC Bank plc, Trinseo Holding S.à r.l., TMF Administration Services Limited and the Law Debenture Trust Corporation plc (incorporated by reference to Exhibit 99.1 to the Current Report on Form 8-K filed April 2, 2024).
10.2§	Form of Retention Award Agreement (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K filed February 27, 2024).
10.3§†	Form of Restricted Stock Unit Award Agreement.
10.4§†	Form of Performance Award Stock Unit Agreement.
10.5§†	Form of Non-statutory Stock Option Award Agreement.
10.6§†	Form of Restricted Cash Unit Award Agreement.
10.7§†	Employment Agreement between Trinseo Netherlands B.V. and Johannes Hendriks, dated August 25, 2022.
31.1†	Certification of Chief Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
31.2†	Certification of Chief Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
32.1†	Certification of Chief Executive Officer Pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
32.2†	Certification of Chief Financial Officer Pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
101.INS†	XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document
101.SCH†	XBRL Taxonomy Extension Schema Document
101.CAL†	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF†	XBRL Taxonomy Extension Definition Linkbase Document
101.LAB†	XBRL Taxonomy Extension Label Linkbase Document
101.PRE†	XBRL Taxonomy Extension Presentation Linkbase Document
104†	Cover Page Interactive Data File (formatted in Inline XBRL and contained in Exhibit 101)

† Filed herewith.

§ Compensatory plan or arrangement.

* Certain portions of this exhibit were redacted pursuant to Item 601(b)(10)(iv) of Regulation S-K. The omitted information is (i) not material and (ii) would likely cause us competitive harm if publicly disclosed. We agree to furnish supplementally an unredacted copy of the exhibit to the Securities and Exchange Commission on its request; provided, however that the Company may request confidential treatment of this exhibit pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, duly authorized.

Date: May 9, 2024

TRINSEO PLC
By:	/s/ Frank Bozich
Name:	Frank Bozich
Title:	President, Chief Executive Officer
	(Principal Executive Officer)
By:	/s/ David Stasse
Name:	David Stasse
Title:	Executive Vice President, Chief Financial Officer
	(Principal Financial Officer)

EX-10.3

Exhibit 10.3

Name:

Number of Restricted Stock Units subject to Award:

Date of Grant:

Trinseo PLC

Amended & Restated 2014 Omnibus Incentive Plan

Restricted Stock Unit Agreement

Thisagreement(this“Agreement”)evidencesanaward(the“Award”)ofrestricted stockunits(the“Restricted Stock Units”)grantedbyTrinseoPLC(the“Company”)tothe undersigned(the“Grantee”)pursuanttotheTrinseo PLC Amended and Restated 2014OmnibusIncentivePlan(as amended from time to time, the “Plan”), which is incorporated herein byreference.

1.Grant of Restricted Stock Units. On the date of grant set forth above (the “Grant Date”) the Company granted to the Grantee an award consisting of the right to receive, on the terms provided herein and in the Plan, one share of Stock with respect to each Restricted Stock Unit forming part of the Award, in each case, subject to adjustment pursuant to Section 7 of the Plan in respect of transactions occurring after the datehereof.

The grant of the Restricted Stock Units is a one-time benefit and does not create any contractual or other right for the Grantee to receive a grant of restricted stock units or benefits in lieu of restricted stock units in the future.

The Award shall not be interpreted to bestow upon the Grantee any equity interest or ownership in the Company or any Affiliate prior to the date on which the Company delivers shares of Stock to the Grantee (if any). The Grantee is not entitled to vote any shares of Stock by reason of the granting of this Award or to receive or be credited with any dividends declared and payable on any share of Stock prior to the date on which any such share is delivered to the Grantee hereunder. The Grantee shall have the rights of a shareholder only as to those shares of Stock, if any, that are delivered under this Award.

2.Meaning of Certain Terms. Except as otherwise defined herein, all capitalized terms used herein have the same meaning as in thePlan.

3.Dividend Equivalents. During the period beginning on the Grant Date and ending on the date that shares of Stock are issued in settlement of vested Restricted Stock Units, the Grantee will accrue dividend equivalents on the Restricted Stock Units equal to any cash dividend or cash distribution that would have been paid on the Restricted Stock Unit had that Restricted Stock Unit been an issued and outstanding share of Stock on the recorddateforthedividendordistribution.Suchaccrueddividendequivalents(i)willvest and become payable upon the same terms and at the same time of settlement as the Restricted Stock Unit to which they relate (and will be payable with respect to any shares of Stock that are issued or that are withheld pursuant to Section 8 in order to satisfy Grantee’sTax-RelatedItems),(ii)willbedenominatedandpayablesolelyincashandpaid insuchmannerastheCompanydeemsappropriate,and(iii)willnotbearoraccrueinterest. Dividend equivalent payments, at settlement, will be net of applicable federal, state,local and foreign income and social insurance withholding taxes as provided in Section 8.

Exhibit 10.3

Upon the forfeiture of the Restricted Stock Units, any accrued dividend equivalents attributable to such Restricted Stock Units will also be forfeited.

4.Vesting, etc.

(a) TheAwardshallvestinthree equal installments on the first, second and third anniversary of the Grant Date (each such date, a “Vesting Date”), subjecttotheGrantee’scontinuedEmploymentwiththeCompanythrough each applicable Vesting Date.

(b) Exceptasprovidedinsections(c)and(d)below,iftheGrantee’s Employment with the Company terminates for any reason prior to any Vesting Date, the unvested portion of the Award will be automatically and immediately forfeited upon suchtermination.

(c) If the Grantee’s Employment terminates due to his or her Retirement (as defined below), death, Permanent Disability, or due to a restructuring or redundancy, in each case, prior to any Vesting Date, the Award, to the extent then outstanding, will be treated as follows:

i. IftheGrantee’sEmploymentterminatesasaresultoftheGrantee’s Retirement (as defined below), following such termination the Award will continue to vest as if the Grantee had remainedincontinuousEmploymentthroughthe Vesting Date. For purposes hereunder, “Retirement” means a retirement from active Employment after the Grantee has attained age 55 with at least 10 years of continuous service with the Company, or its predecessor entity, The Dow Chemical Company, oranyofitssubsidiaries,orasdefinedintheGrantee'semployment or other agreement with theCompany.

ii.IftheGrantee’sEmploymentisterminatedduetohisorherdeathor by the Company due to his or her Permanent Disability, upon such termination, the Award will immediately vest in full as to the total number of Restricted Stock Units subject to theAward.

iii.If the Grantee’s Employment is terminated by the Company other than for Cause in connection with a restructuring or redundancy, as determinedbytheCompany,uponsuchtermination,theAwardwill vest in full as to the total number of Restricted Stock Units subject to the Award.

(d) If, within the twenty-four (24)-month period following the occurrence of a Change in Control (as defined below), (A) the Grantee’s Employment is terminated by the Company other than for Cause or, (B) if the Grantee is a current member of the Company’s executive leadership team and is subjecttoaneffectiveemploymentorotherindividualagreement withtheCompanythatprovidestheGranteewiththeabilitytoterminatehis or her employment for “good reason” (with such term having the meaning

Exhibit 10.3

ascribed thereto in the employment or other individual agreement, if any, between the Grantee and the Company for so long as such agreement is in effect), upon such termination and in lieu of the treatment provided for in Section 4(b)ii above, the Award, to the extent then outstanding, will immediately vest in full as to the total number of Restricted Stock Units subject to theAward.

i. ForpurposesofthisAgreement,“ChangeinControl”meansthefirst to occur of any of the followingevents:

1. an event in which any “person,” as such term is used in Sections 13(d) and 14(d) of the U.S. Securities Exchange Act of 1934, as amended(the“1934 Act”)(otherthan(A)theCompany,(B)any subsidiaryoftheCompany,(C)anytrusteeorotherfiduciary holding securities under an employee benefit plan of the CompanyorofanysubsidiaryoftheCompany,and(D)any company owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as theirownershipofstockoftheCompany),isorbecomesthe “beneficial owner” (as defined in Section 13(d) of the 1934 Act),togetherwithallaffiliatesandassociates(assuchterms areusedinRule12b-2oftheGeneralRulesandRegulations underthe1934Act)ofsuchperson,directlyorindirectly,of securities of the Company representing 40% or more of the combined voting power of the Company’s then outstanding securities;

2. the consummation of the merger or consolidation of the Company with any other company, other than (i) a merger or consolidation which would result in the voting securities of the Company outstanding immediately prior thereto continuing to represent (either by remaining outstanding or by being converted into voting securities of the surviving entity), in combination with the ownership of any trustee or otherfiduciaryholdingsecuritiesunderanemployeebenefit plan of the Company or any subsidiary of the Company, more than 50% of the combined voting power of thevoting securities of the Company or such surviving entity outstanding immediately after such merger or consolidation and (ii) a merger or consolidation effected to implement a recapitalizationoftheCompany(orsimilartransaction)after which no “person” “beneficially owns” (with the determination of such “beneficial ownership” on the same basisassetforthinclause(1)ofthisdefinition)securitiesof the Company or the surviving entity of such merger or consolidation representing 50% or more of the combined voting power of the securities of the Company or the surviving entity of such merger or consolidation;or

Exhibit 10.3

3. the complete liquidation of the Company or the sale or disposition by the Company of all or substantially all of the Company’sassets.

Notwithstanding the foregoing, to the extent any amount constituting “nonqualified deferred compensation” subject to Section409AwouldbecomepayableundertheAwardbyreason ofaChangeinControl,itshallbecomepayableonlyiftheevent or circumstances constituting the Change in Control would also constitute a change in the ownership or effective control of the Company, or a change in the ownership of a substantial portion of the Company’s assets, within the meaning of subsection (a)(2)(A)(v) of Section 409A and the Treasury Regulations thereunder.

5.Delivery of Stock. Subject to Section 9(b), the Company shall, as soon as practicable upon the vesting of the Restricted Stock Units or any portion thereof as providedinSection4(a),(c)or(d)ofthisAgreement(butinnoeventlaterthanthirty(30) daysfollowingthedateonwhichsuchRestrictedStockUnits,oranyportionthereof,vest) effect delivery of the Stock with respect to such vested Restricted Stock Units, or any portion thereof, to the Grantee (or, in the event of the Grantee’s death, to the Grantee’s beneficiary, which for purposes hereunder shall be (a) if permitted by the Administrator, the person(s) who has been designated by the Grantee in writing in a form and manner acceptabletotheAdministratortoreceivetheAwardintheeventoftheGrantee’sdeathor (b) in the event no beneficiary designation has been made by the Grantee, the Grantee’s estate). No Stock will be issued pursuant to this Award unless and until all legal requirementsapplicabletotheissuanceortransferofsuchStockhavebeencompliedwith to the satisfaction of the Administrator, including, for the avoidance of doubt to the extent required by Irish law, the payment by the Grantee to the Company of an amount incashequaltotheaggregateparvalueofthesharesofStocktobedeliveredinrespectof the vested Restricted Stock Units on, or within thirty (30) days of, the vesting of the Restricted Stock Units. The actual amount the Grantee will be required to pay will be determinedatthetimethattheAwardvestsbasedontheparvalueoftheCompany’sStock on the final VestingDate.

6.Forfeiture; Recovery of Compensation.ByacceptingtheAwardtheGrantee expressly acknowledges and agrees that his or her rights (and those of any permitted transferee) under the Award or to any Stock acquired under the Award or any proceeds from the disposition thereof, are subject to Section 6(a)(5) of the Plan (including any successor provision). Without limiting the foregoing, the Administrator may recover Restricted Stock Units, or shares granted upon settlement of Restricted Stock Units, in accordance with the Company’s Policy for Recoupment of Incentive Compensation (as may be amended from time to time) or as otherwise required by applicable law or applicable stock exchange listing standards. Nothing in the preceding sentence shall be construed as limiting the general application of Section 12 of thisAgreement.

7.Nontransferability. Neither the Award nor the Restricted Stock Units may be transferred except at death in accordance with Section 6(a)(3) of thePlan.

Exhibit 10.3

8.Responsibility for Taxes & Withholding. Regardless of any action the Company or any of its Affiliates takes with respect to any or all income tax, social insurance, payroll tax, payment on account or other tax-related items related to the Grantee’s participation in the Plan and legally applicable to the Grantee (“Tax-Related Items”), the Grantee acknowledges that the ultimate liability for all Tax-Related Items is and remains the Grantee’s responsibility and may exceed the amount actually withheld by theCompanyoranyofitsAffiliates.TheGranteefurtheracknowledgesthattheCompany and/oritsAffiliates(a)makenorepresentationsorundertakingsregardingthetreatmentof any Tax-Related Items in connection with any aspect to the Restricted Stock Units, including,butnotlimitedto,thegrant,vestingorsettlementoftheRestrictedStockUnits, theissuanceofStockuponsettlementoftheRestrictedStockUnits,thesubsequentsaleof Stock acquired pursuant to such issuance and the receipt of any dividends and/ordividend equivalents;and(b)donotcommittoandareundernoobligationtostructurethetermsof anyAwardtoreduceoreliminateGrantee’sliabilityforTax-RelatedItemsorachieveany particular tax result. Further, if the Grantee becomes subject to tax in more than one jurisdictionbetweenthedateofgrantandthedateofanyrelevanttaxableevent,theGrantee acknowledges that Company and/or its Affiliates may be required to withhold or account for Tax-Related Items in more than onejurisdiction.

Prior to any relevant taxable or tax withholding event, as applicable, the Grantee will pay or make adequate arrangements satisfactory to the Company and/or its Affiliates tosatisfyallTax-RelatedItems.Inthisregard,theGranteeauthorizestheCompanyand/or its Affiliates, or their respective agents, at their discretion, to satisfy the obligations with regard to all Tax-Related Items by one or a combination of thefollowing:

(i)withholding from the Grantee’s wages/salary or other cash compensation paid to the Grantee by the Company and/or its Affiliates;or

(ii)withholding from proceeds of the Stock acquired upon vesting/settlement of the Restricted Stock Units either through a voluntary sale or through a mandatory sale arranged by the Company (on Grantee’s behalf pursuant to this authorization);or

(iii)withholding in Stock to be issued upon vesting/settlement of the RestrictedStockUnitsprovided,however,thatiftheGranteeisaSection16officerofthe Company under the 1934 Act, then the CompanywillwithholdinsharesofStockupontherelevanttaxableortaxwithholding event, as applicable, unless the use of such withholding method is problematic under applicable tax or securities law or has materially adverse accounting consequences, in whichcase,theobligationforTax-RelatedItemsmaybesatisfiedbyoneoracombination of methods (i) and (ii)above.

To avoid negative accounting treatment, the Company and/or its Affiliates may withhold or account for Tax-Related Items by considering applicable minimum statutory withholding amounts or other applicable withholding rates. If the obligation for Tax- RelatedItemsissatisfiedbywithholdinginStock,fortaxpurposes,theGranteeisdeemed tohavebeenissuedthefullnumberofsharesofStockattributabletothevestedRestricted Stock Units, notwithstanding that a number of share are held back solely for the purpose ofpayingtheTax-RelatedItemsdueasaresultofanyaspectoftheGrantee’sparticipation in thePlan.

Exhibit 10.3

The Grantee shall pay to the Company and/or its Affiliates any amount of Tax- Related Items that the Company and/or its Affiliates may be required to withhold or accountforasaresultoftheGrantee’sparticipationinthePlanthatwillnotforanyreason besatisfiedbythemeanspreviouslydescribed.TheCompanymayrefusetoissueordeliver the Stock or the proceeds of the sale of Stock if the Grantee fails to comply with the Grantee’s obligations in connection with the Tax-RelatedItems.

By accepting this grant of Restricted Stock Units, the Grantee expressly consents to the methods of withholding Tax-Related Items by the Company and/or its Affiliates as setforthherein,includingthewithholdingofStockandthewithholdingfromtheGrantee's wages/salaryorotheramountspayabletotheGrantee.AllotherTax-RelatedItemsrelated to the Restricted Stock Units and any Stock delivered in satisfaction thereof are the Grantee's soleresponsibility.

9.Other Tax Matters.

(a) The Grantee expressly acknowledges that because this Award consists of anunfundedandunsecuredpromisebytheCompanytodeliverStockinthe future, subject to the terms hereof, it is not possible to make a so-called “83(b) election” under U.S. federal tax laws with respect to theAward.

(b) If,atthetimeoftheGrantee’sterminationofemployment,theGranteeisa “specified employee,” as defined below, to the extent required by Section 409A, any and all amounts payable on account of the Grantee’s separation from service that constitute deferred compensation and would (but for this provision) be payable within six (6) months following the date of termination, shall instead be paid on the next business day following the expiration of such six (6) month period or, if earlier, upon the Grantee’s death. For purposes of this Agreement, all references to “termination of employment” and correlative phrases shall be construed to require a “separation from service” (as defined in Treasury Regulations section 1.409A-1(h) after giving effect to the presumptions contained therein), and the term “specified employee” means an individual determined bythe Company to be a specified employee under Treasury Regulation section 1.409A-1(i). Each payment made under this Agreement shall be treated as a separate payment and the right to a series of installment payments under this Agreement is to be treated as a right to a series of separate payments.

10.Effect on Employment. Neither the grant of the Restricted Stock Units,nor the delivery of Stock upon vesting of any portion thereof, will give the Grantee any right to be retained in the employ or service of the Company or any of its Affiliates, affect the rightoftheCompanyoranyofitsAffiliatestodischargeordisciplinesuchGranteeatany time, or affect any right of such Grantee to terminate his or her Employment at anytime.

11.Acknowledgements. By accepting the Award, the Grantee agrees to be bound by, and agrees that the Award and the Restricted Stock Units are subject in all respects to, the terms of the Plan. The Grantee further acknowledges and agrees that (i)

Exhibit 10.3

this Agreement may be executed in two or more counterparts, each of which shall be an original and all of which together shall constitute one and the same instrument, (ii) this agreement may be executed and exchanged using facsimile, portable document format (PDF)orelectronicsignature,which,ineachcase,shallconstituteanoriginalsignaturefor allpurposeshereunderand(iii)suchsignaturebytheCompanywillbebindingagainstthe Company and will create a legally binding agreement when this Agreement is countersigned by theGrantee.

12.Authorization to Release and Transfer Necessary Personal Information. The Grantee hereby explicitly and unambiguously consents to the collection, use and transfer,inelectronicorotherform,ofhisorherpersonaldatabyandamong,asapplicable, the Company and the Affiliates for the exclusive purpose of implementing, administering and managing the Grantee’s participation in the Plan. The Grantee understands that the Company and the Affiliates may hold certain personal information about the Grantee including, but not limited to, the Grantee’s name, home address and telephone number, dateofbirth,socialsecuritynumber(oranyothersocialornationalidentificationnumber), salary, nationality, job title, number of Restricted Stock Units and/or Stock held and the details of all Restricted Stock Units or any other entitlement to Stock awarded, cancelled, vested, unvested or outstanding for the purpose of implementing, administering and managing the Grantee’s participation in the Plan (the “Data”). The Grantee understands that the Data may be transferred to the Company or any of the Affiliates, or to any third parties assisting in the implementation, administration and management of the Plan, that these recipients may be located in the Grantee’s country or elsewhere, and that any recipient’s country (e.g., the United States) may have different data privacy laws and protectionsthantheGrantee’scountry.TheGranteeunderstandsthatheorshemayrequest alistwiththenamesandaddressesofanypotentialrecipientsoftheDatabycontactinghis or her local human resources representative. The Grantee authorizes the recipients to receive, possess, use, retain and transfer the Data, in electronic or other form, for the sole purposeofimplementing,administeringandmanaginghisorherparticipationinthePlan, including any requisite transfer of such Data to a broker or other third party assisting with the administration of Restricted Stock Units under the Plan or with whom Stock acquired pursuant to the vesting of the Restricted Stock Units or cash from the sale of such Stock may be deposited.Furthermore, the Grantee acknowledges and understands that the transferoftheDatatotheCompanyortheAffiliatesortoanythirdpartiesisnecessaryfor hisorherparticipationinthePlan.TheGranteeunderstandsthatDatawillbeheldonlyas long as is necessary to implement, administer and manage his or her participation in the Plan. The Grantee understands that he or she may, at any time, view the Data, request additionalinformationaboutthestorageandprocessingoftheData,requireanynecessary amendmentstotheDataorrefuseorwithdrawtheconsentshereinbycontactinghisorher local human resources representative in writing. The Grantee further acknowledges that withdrawal of consent may affect his or her ability to vest in or realize benefits from the Restricted Stock Units, and his or her ability to participate in the Plan. For more information on the consequences of refusal to consent or withdrawal of consent, the Grantee understands that he or she may contact his or her local human resources representative.

Finally, upon request of the Company or the Grantee’s employer (the “Employer”), the Grantee agrees to provide an executed data privacy consent form (or any other agreements or consents that may be required by the Company and/or the

Exhibit 10.3

Employer) that the Company and/or the Employer may deem necessary to obtain from the Grantee forthepurposeofadministeringtheGrantee’sparticipationinthePlanincompliancewith the data privacy laws in the Grantee’s country, either now or in the future. The Grantee understands and agrees that the Grantee will not be able to participate in the Plan if the Grantee fails to provide any such consent or agreement requested by the Company and/or the Employer.

13.Electronic Delivery and Execution. The Grantee hereby consents and agrees to electronic delivery of any documents that the Company may elect to deliver (including, but not limited to, plan documents, prospectus and prospectus supplements, grant or award notifications and agreements, account statements, annual and quarterly reports, and all other forms of communications) in connection with this and any other Award made or offered under the Plan. The Grantee understands that, unless revoked by theGranteebygivingwrittennoticetotheCompanypursuanttothePlan,thisconsentwill beeffectiveforthedurationoftheAgreement.TheGranteealsounderstandsthatheorshe will have the right at any time to request that the Company deliver written copies of any andallmaterialsreferredtoabove.TheGranteeherebyconsentstoanyandallprocedures the Company has established or may establish for an electronic signature system for deliveryandacceptanceofanysuchdocumentsthattheCompanymayelecttodeliver,and agree that his or her electronic signature is the same as, and will have the same force and effect as, his or her manual signature. The Grantee consents and agrees that any such procedures and delivery may be affected by a third party engaged by the Company to provide administrative services related to thePlan.

14.Appendix. Notwithstanding any provision of the Agreement to the contrary, this Restricted Stock Unit grant and the Stock acquired under the Plan shall be subject to any and all special terms and provisions as set forth in the Appendix, if any, for the Grantee’s country of residence (and country of employment, ifdifferent). Moreover, if the Grantee relocates to one of the countries included in the Appendix, the additional terms and conditions for such country will apply to the Grantee, to the extent the Company determines that the application of such terms and conditions is necessary or advisable for legal or administrative reasons.  The Appendix constitutes part of the Agreement.

15.Severability.TheprovisionsofthisAgreementareseverableandifanyone or more provisions are determined to be illegal or otherwise unenforceable, in whole or in part, the remaining provisions shall nevertheless be binding andenforceable.

[Signature page follows.]

Exhibit 10.3

IN WITNESS WHEREOF, the Company has caused this Agreement to be executed by its duly authorized officer.

TRINSEO PLC

By:

Name:

Title:

Dated:

Acknowledged and Agreed:

By:

Signature Page to Restricted Stock Unit Agreement

Exhibit 10.3

COUNTRY APPENDIX

ADDITIONAL TERMS AND CONDITIONS TO RESTRICTED STOCK UNIT AGREEMENT

ThisCountryAppendix(“Appendix”)includesthefollowingadditionaltermsandconditionsthat governtheGrantee’sRestrictedStockUnitAwardforall the Granteesthatresideand/orworkoutside of the UnitedStates.

Notifications

This Appendix also includes information regarding exchange controls and certain other issuesofwhichtheGranteeshouldbeawarewithrespecttotheGrantee’sparticipationinthePlan. The information is based on the securities, exchange control and other laws in effect in the respective countries as of January 2022. Such laws are often complex and change frequently. Asaresult,theCompanystronglyrecommendsthattheGranteenotrelyontheinformationinthis AppendixastheonlysourceofinformationrelatingtotheconsequencesoftheGrantee’s participationinthePlanbecausetheinformationmaybeoutofdateatthetimethattheRestricted Stock Units vest, or Stock is delivered in settlement of the Restricted Stock Units, or the Grantee sells any Stock acquired under thePlan.

In addition, the information contained herein is general in nature and may not apply to the Grantee’sparticularsituation,andnoneoftheCompany,itsAffiliates,northeAdministratorisin a position to assure the Grantee of a particular result. Accordingly, the Grantee is advised to seek appropriate professional advice as to how the relevant laws in the Grantee’s country of residence and/or work may apply to the Grantee’ssituation.

Finally, if the Grantee transfers employment after the Grant Date, or is considered a resident of anothercountryforlocallawpurposesfollowingtheGrantDate,thenotificationscontainedherein may not be applicable to the Grantee, and the Administrator shall, in its discretion, determine to what extent the terms and conditions contained herein shall be applicable to theGrantee.

Terms and Conditions Applicable to All Non-U.S. Jurisdictions

English Language. The Grantee acknowledges and agrees that it is the Grantee’s express intent that this Agreement, the Plan and all other documents, rules, procedures, forms, notices and legal proceedingsenteredinto,givenorinstitutedpursuanttotheRestrictedStockUnitAward,bedrawn upinEnglish.IftheGranteehasreceivedthisAgreement,thePlanoranyotherrules,procedures, forms or documents related to the Restricted Stock Unit Award translated into a language other thanEnglish,andifthemeaningofthetranslatedversionisdifferentthantheEnglishversion,the English version willcontrol.

Compliance with Law.  Notwithstanding any other provision of the Plan or this Agreement, unless there is an exemption from any registration, qualification or other legal requirement applicable to the Stock, the Company shall not be required to deliver any shares issuable upon settlement of the RestrictedStockUnit prior to the completion of any registration or qualification of the shares under any local, state, federal or foreign securities or exchange control law or under rulings or regulations of the U.S. Securities and Exchange Commission (“SEC”) or of any other governmental regulatory body, or prior to obtaining any approval or other clearance from any local, state, federal or foreign governmental agency, which registration, qualification or approval

Exhibit 10.3

the Company shall, in its absolute discretion, deem necessary or advisable. The Grantee understands that the Company is under no obligation to register or qualify the shares with the SEC or any state or foreign securities commission or to seek approval or clearance from any governmental authority for the issuance or sale of the shares.  Further, the Grantee agrees that the Company shall have unilateral authority to amend the Agreement without the Grantee’s consent to the extent necessary to comply with securities or other laws applicable to issuance of shares of Stock.

Insider Trading/Market Abuse.  The Grantee acknowledges that, depending on the Grantee’s or his or her broker's country or where the shares of Stock are listed, the Grantee may be subject to insider trading restrictions and/or market abuse laws which may affect the Grantee’s ability to accept, acquire, sell or otherwise dispose of shares of Stock, rights to shares of Stock (e.g., RestrictedStockUnits) or rights linked to the value of shares of Stock (e.g., phantom awards, futures) during such times the Grantee is considered to have “inside information” regarding the Company as defined in the laws or regulations in the applicable jurisdictions).  Local insider trading laws and regulations may prohibit the cancellation or amendment of orders the Grantee placed before the Grantee possessed inside information.  Furthermore, the Grantee could be prohibited from (i) disclosing the inside information to any third party (other than on a “need to know” basis) and (ii) “tipping” third parties or causing them otherwise to buy or sell securities.  Keep in mind third parties includes fellow employees.  Any restrictions under these laws or regulations are separate from and in addition to any restrictions that may be imposed under any applicable insider trading policy of the Company.  The Grantee is responsible for complying with any restrictions and should speak to his or her personal advisor on this matter.

Exchange Control, Foreign Asset/Account and/or Tax Reporting.  Depending upon the country to which laws the Grantee is subject, the Grantee may have certain foreign asset/account and/or tax reporting requirements that may affect the Grantee’s ability to acquire or hold shares of Stock under the Plan or cash received from participating in the Plan (including from any dividends or dividend equivalents or sale proceeds arising from the sale of shares of Stock) in a brokerage or bank account outside the Grantee’s country of residence.  The Grantee’s country may require that the Grantee reports such accounts, assets or transactions to the applicable authorities in his or her country.  The Grantee also may be required to repatriate cash received from participating in the Plan to the Grantee’s country within a certain period of time after receipt.  The Grantee is responsible for knowledge of and compliance with any such regulations and should speak with his or her personal tax, legal and financial advisors regarding same.

Commercial Relationship. The Grantee expressly recognizes that the Grantee’s participation in thePlanandtheCompany’sAwardgrantdoesnotconstituteanemploymentrelationshipbetween the Grantee and the Company. The Grantee has been granted Restricted Stock Units as a consequence of the commercial relationship between the Company and the Employer, and the Employer is the Grantee’s sole employer. Based on the foregoing, (a) the Grantee expressly recognizes the Plan and the benefits the Grantee may derive from participation in the Plan do not establish any rights between the Grantee and the Affiliate that employs the Grantee, (b) the Plan and the benefits the Grantee may derive from participation in the Plan are not part of the employmentconditionsand/orbenefitsprovidedbytheAffiliatethatemploystheGrantee,and(c) any modifications or amendments of the Plan by the Company or the Administrator, or a termination of the Plan by the Company, shall not constitute a change or impairment of the terms and conditions of the Grantee’s employment with the Affiliate that employs theGrantee.

Exhibit 10.3

Private Placement. The grant of the Award is not intended to be a public offering of securities in the Grantee’s country of residence and/or employment but instead is intended to be a private placement. As a private placement, the Company has not submitted any registration statement, prospectus or other filings with the local securities authorities (unless otherwise required under local law), and the grant of the Restricted Stock Unit Award is not subject to the supervision of the local securities authorities.

Additional Acknowledgements. The GRANTEE also acknowledges and agrees to the following:

● ThePlanisestablishedvoluntarilybytheCompany,itisdiscretionaryinnature,anditmay bemodified,amended,suspendedorterminatedbytheCompanyatanytime,totheextent permitted by thePlan.

● All decisions with respect to future Awards or other grants, if any, will be at the sole discretion of theCompany.

●The future value of the underlying Stock is unknown, undeterminable and cannot be predicted withcertainty.

● TheAwardandtheStocksubjecttotheAward,andtheincomeandvalueofsame,arenot partofnormalorexpectedcompensationorsalaryforanypurposeandarenotintendedto replace any pension rights orcompensation.

●The Grantee’s participation in the Plan isvoluntary.

● No claim or entitlement to compensation or damages arises from the forfeiture of the Award or any of the Restricted Stock Units, the termination of the Plan, or the diminution in value of the Restricted Stock Units or Stock, and the Grantee irrevocably releases the Company,itsAffiliates,theAdministratorandtheiraffiliatesfromanysuchclaimthatmay arise.

● TheRestricted Stock Unit andtheStocksubjecttotheRestricted Stock Unit,andtheincomeandvalueofsame,arenot part of normal or expected compensation for purposes of, including but not limited to, calculating any severance, resignation, termination, redundancy, dismissal, end-of-service payments, bonuses, holiday pay, long-service awards, pension or retirement or welfare benefits or similarpayments.

● UnlessotherwiseagreedwiththeCompanyinwriting,theAwardandtheStocksubjectto the Restricted Stock Unit, and the income and value of same, are not granted as consideration for, or in connection with, any service the Grantee may provide as a director of the Company or its Affiliates.

● Neither the Company nor its Affiliates shall be liable for any foreign exchange rate fluctuation between the Grantee's local currency and the U.S. Dollar that may affect the value of the Restricted Stock Units or of any amounts due to the Grantee pursuant to the settlement oftheRestrictedStockUnitsorthesubsequentsaleofanyStockacquireduponsettlement.

Exhibit 10.3

● None of the Company, its Affiliates, nor the Administrator is providing any tax, legal or financial advice or making any recommendations regarding the Grantee’s participation in the Plan, the grant, vesting or settlement of the Grantee’s Restricted Stock Units, or the Grantee’s acquisition or sale of the Stock delivered in settlement of the Restricted Stock Units. The Grantee is hereby advised to consult with his own personal tax, legal and financialadvisorsregardinghisparticipationinthePlanbeforetakinganyactionrelatedto thePlan.

Exhibit 10.3

EUROPEAN UNION (“EU”) / EUROPEAN ECONOMIC AREA (“EEA”) / SWITZERLAND / UNITED KINGDOM

Terms and Conditions

Employee Data Privacy. If the Grantee resides and/or works in the EU/EEA, Switzerland or the United Kingdom, the following provisions replace Section 12 of the Agreement in its entirety:

The Company, with its address at 440 E. Swedesford Road, Suite 301, Wayne, PA 19087, USA, is the controller responsible for the processing of the Grantee’s personal data by the Company and the third parties noted below, and itsrepresentativeinItalyforprivacypurposes is A.P.I. Applicazioni Plastiche Industriali S.p.A. with its registered address at Via Dante Alighieri n. 27, 36065 Mussolente (VI)Italy.

(a)Data Collection and Usage. Pursuant to applicable data protection laws, the Grantee is hereby notified that the Company collects, processes and uses certain personally-identifiable information about the Grantee for the legitimate interest of implementing, administering and managing the Plan and generally administering equity awards; specifically, including the Grantee’s name, home address, email address and telephone number, date of birth, social insurance number or other identification number, salary, citizenship, job title, any shares of Stock or directorships held in the Company, and details of all Restricted Stock Units, any other entitlement to shares of Stock awarded, canceled, exercised, vested, or outstanding in the Grantee’s favor, which the Company receives from the Grantee or the Grantee’s employer (“Personal Data”). In granting the Restricted Stock Units under the Plan, the Company will collect Personal Data for purposes of allocating shares of Stock and implementing, administering and managing the Plan. The Company’s legal basis for the collection, processing and use of Personal Data is the necessity of the processing for the Company to perform its contractual obligations under the Agreement and the Plan and the Company’s legitimate business interests of managing the Plan, administering employee equity awards and complying with its contractual and statutory obligations.

(b)Stock Plan Administration Service Provider. The Company transfers Personal Data to Merrill Lynch and its affiliates, an independent service provider based in the United States, which assists the Company with the implementation, administration and management of the Plan. In the future, the Company may select a different service provider and share Personal Data with another company that serves in a similar manner. The Company’s service provider will open an account for the Grantee to receive and trade shares of Stock. The Grantee will be asked to agree on separate terms and data processing practices with the service provider, which is a condition to the Grantee’s ability to participate in the Plan. The processing of Personal Data will take place through both electronic and non-electronic means. Personal Data will only be accessible by those individuals requiring access to it for purposes of implementing, administering and operating the Plan.

(c)International Data Transfers. The Company and its service providers are based in the United States or elsewhere throughout the world. The Grantee’s country or jurisdiction may have different data privacy laws and protections than the United States. The Company's legal basis for the transfer of the Grantee’s Personal Data to the United States is to satisfy its contractual obligations under the terms and conditions of this Agreement.

Exhibit 10.3

(d)Data Retention. The Company will use Personal Data only as long as is necessary to implement, administer and manage the Grantee’s participation in the Plan or as required to comply with legal or regulatory obligations, including tax and securities laws. When the Company no longer needs Personal Data, the Company will remove it from its systems. If the Company keeps Personal Data longer, it would be to satisfy legal or regulatory obligations and the Company’s legal basis would be for compliance with relevant laws or regulations.

(e)Data Subject Rights. The Grantee may have a number of rights under data privacy laws in the Grantee’s country. For example, the Grantee’s rights may include the right to (i) request access or copies of Personal Data the Company processes, (ii) request rectification of incorrect Personal Data, (iii) request deletion of Personal Data, (iv) place restrictions on processing of Personal Data, (v) lodge complaints with competent authorities in the Grantee’s country, and/or (vi) request a list with the names and addresses of any potential recipients of Personal Data. To receive clarification regarding the Grantee’s rights or to exercise the Grantee’s rights, the Grantee may contact his or her local partner or human resources representative.

BELGIUM

Notifications

Foreign Asset / Account Reporting Information. If Grantee is a Belgian resident, Grantee is required to report any taxable income attributable to the grant of the Restricted Stock Units on his or her annual tax return. In addition, the Grantee is required to report any securities (e.g., Stock) or bank accounts openedandmaintainedoutsideBelgiumonhisorherannualtaxreturn.Inaseparatereport,certain details regarding such foreign accounts (including the account number, bank name and countryin which such account was opened) must be provided to the Central Contact Point of the National Bank ofBelgium. The form, as well as additional information on how to complete it, can be found on the website of the National Bank of Belgium (www.nbb.be) under the caption Kredietcentrales / Centrales des crédits.

Stock Exchange Tax.  A stock exchange tax applies to transactions executed by a Belgian resident through a financial intermediary, such as a bank or broker.  If the transaction is conducted through a Belgian financial intermediary, it may withhold the stock exchange tax, but if the transaction is conducted through a non-Belgian financial intermediary, the Belgian resident may need to report and pay the stock exchange tax directly.  The stock exchange tax likely will apply when shares of Stock acquired under the Plan are sold.  Belgian residents should consult with a personal tax or financial advisor for additional details on their obligations with respect to the stock exchange tax.

Annual Securities Account Tax Information.  An annual securities accounts tax may be payable if the total value of securities held in a Belgian or foreign securities account (e.g., shares acquired under the Plan) exceeds a certain threshold on four reference dates within the relevant reporting period (i.e., December 31, March 31, June 30 and September 30).  In such case, the tax will be due on the value of the qualifying securities held in such account.  The Grantee should consult with his or her personal tax advisor regarding the application of this tax.

Exhibit 10.3

DENMARK

Terms and Conditions

Stock Option Act.  Notwithstanding any provisions in the Agreement to the contrary, if the Grantee is determined to be an "Employee," as defined in section 2 of the Danish Act on the Use of Rights to Purchase or Subscribe for Shares, etc. in Employment Relationships (the "Stock Option Act"), the treatment of the Award upon termination of employment shall be governed by the Stock Option Act.  However, if the provisions in the Agreement or the Plan governing the treatment of the Award upon a termination are more favorable, the provisions of the Agreement or the Plan will govern.

FRANCE

Terms and Conditions

Use of English Language. Les parties reconnaissent avoir exigé la rédaction en anglais de la présente convention, ainsi que de tous documents exécutés, avis donnés et procédures judiciaires intentées, directement ou indirectement, relativement à ou suite à la présente convention.

Notifications

Award Not French Qualified. The Grantee understands and acknowledges that the Restricted Stock Units granted under this Agreement are not intended to qualify for specific tax and social security treatment pursuant to Sections L. 225-197-1 to L. 225-197-5 and Sections L. 22-10-59 and L. 22-10-60 of the French Commercial Code, as amended.

Exchange Control Information. Grantee must declare to the customs and excise authorities any cash or securities he or she imports or exports without the use of a financial institution when the value of the cash or securities is equal to or exceeds €10,000.

Foreign Account / Assets Reporting Information. If the Grantee is a French resident and retains Stock acquired under the Plan outside of France or maintains a foreign bank account, the Grantee is required to report such to the French tax authorities when filing the Grantee's annual tax return. Failure to comply could trigger significant penalties.

GERMANY

Notifications

Exchange Control Information. Cross-border payments in excess of €12,500 must be reported monthlytotheGermanFederalBank.IftheGranteeusesaGermanbanktotransferacross-border paymentinexcessof€12,500inconnectionwiththesaleoftheStockacquiredunderthePlan,the bank will make the report for the Grantee. Grantee is responsible for satisfying any applicable reporting obligation.

HONG KONG

Terms and Conditions

Exhibit 10.3

Settlement of Restricted Stock Units.IntheeventthatanyoftheRestrictedStockUnitsaresettled within six (6) months of the Grant Date, the Grantee agrees that the Grantee (or his / her beneficiary) will not sell or otherwise dispose of any such shares of Stock prior to the six (6)-month anniversary of the GrantDate.

Wages.TheRestrictedStockUnitAwardandshares of Stock underlyingtheRestrictedStockUnitAward donotformpartoftheGrantee'swagesforthepurposesofcalculatinganystatutoryorcontractual payments under Hong Kong law. The Company specifically intends that the Plan will not be an occupationalretirementschemeforpurposesoftheOccupationalRetirementSchemesOrdinance.

Notifications

Securities Law Information. Warning:The Restricted Stock Unit Award and any Stock issued pursuant to the settlement of the Restricted Stock Units do not constitute a public offering of securities under Hong Kong law and are available only to employees of the Company and its Affiliates. The Agreement, the Plan, and any rules, procedures, forms or other incidental communication materials have not been prepared in accordance with and are not intended to constitute a “prospectus” for a public offering of securities under the applicable securities legislation in Hong Kong, nor have the documents been reviewed by any regulatory authority in Hong Kong. The Award and any related documentation are intended only for the personal use of each eligible employee of the Company or its Affiliates and may not be distributed to any other person. If the Grantee is in any doubt about any of the contents of the Agreement, the Plan, or any rules, procedures or forms, the Grantee should obtain independent professional advice.

INDIA

Notifications

Exchange Control Information. The Grantee understands that he or she must repatriate any proceeds from the sale of Stock and any cash dividends or dividend equivalents acquired under thePlantoIndiaandconverttheproceedsintolocalcurrencywithin90daysor180daysofreceipt, respectively or such other period of time as may be required under applicable regulations. The Grantee will receive a foreign inward remittance certificate (“FIRC”) from the bank where the Grantee deposits the foreign currency. The Grantee should maintain the FIRC as evidence of the repatriation of funds in the event the Reserve Bank of India or the Employer requests proof of repatriation. The Grantee is responsible for complying with applicable exchange control laws in India.

Foreign Account / Assets Reporting Information. The Grantee is required to declare any foreign bank accounts and any foreign financial assets (including Stock acquired under the Plan) in Grantee’s annual tax return. It is Grantee’s responsibility to comply with this reporting obligation and he or she should consult his or her personal tax advisor in this regard.

INDONESIA

Notifications

Exchange Control Information. Foreign exchange activity is subject to certain reporting requirements. For foreign currency transactions exceeding USD 25,000, the underlying document

Exhibit 10.3

of that transaction will have to be submitted to the relevant local bank.  If the Grantee repatriates funds (e.g., proceeds from the sale of Stock) into Indonesia, the Indonesian bank through which the transaction is made will submit a report of the transaction to the Bank of Indonesia.

For transactions of USD 10,000 or more (or its equivalent in other currency), a more detailed description of the transaction must be included in the report and the Grantee may be required to provide information about the transaction to the bank in order to complete the transaction.

Foreign Account / Assets Reporting Information. Indonesian residents have the obligation to report their worldwide assets (including foreign accounts and Stock acquired under the Plan) in their annual individual income tax return. In addition, if there is a change of position of any of the foreign asset the Grantee holds (including Stock acquired under the Plan), the Grantee must report this change in position (i.e., sale of Stock) to the Bank of Indonesia no later than the 15th day of the month following the change in position.

IRELAND

Notifications

Director Notification Obligation.  Directors, shadow directors and secretaries of an Irish Subsidiary or other affiliate of the Company whose interest in the Company represents more than 1% of the Company’s voting share capital must notify the Irish Subsidiary or other affiliate of the Company in writing when acquiring or disposing of their interest in the Company (e.g., Restricted Stock Units, Stock, etc.), when becoming aware of the event giving rise to the notification requirement, or when becoming a director or secretary if such an interest exist at the time.  This notification requirement also applies to any rights or shares acquired by the director’s spouse or children under the age of 18 (whose interests will be attributed to the director, shadow director or secretary).

ITALY

Terms and Conditions

Plan Document Acknowledgment. The Grantee further acknowledges that he or she has read and specifically and expressly approves the Data Privacy section above as well as the following sections of the Agreement Section 1 (“Grant of Restricted Stock Units”); Section 4 (“Vesting”); Section 5 (“Delivery of Stock”), Section 6 (“Forfeiture; Recovery of Compensation”); Section 7 (“Nontransferability”); Section 8 (“Responsibility for Taxes & Withholding”); Section 13 (“Imposition of Other Requirements”);Appendix (“English Language”; “Additional Acknowledgements”).

Notifications

Foreign Asset / Account Reporting Information. The Grantee understands that if the Grantee is an Italian resident and at any time during the fiscal year the Grantee holds foreign financial assets (including cash and Stock) which may generate income taxable in Italy, the Grantee is required to report these assets on the Grantee’s annual tax return (UNICO Form, RW Schedule) for the year during which the assets are held, or on a special form if no tax return is due.  These reporting obligations will also apply to Italian residents who are the beneficial owners of foreign financial assets, even if the Grantee does not directly hold investments abroad or foreign assets.

Exhibit 10.3

Tax on Foreign Financial Assets. Individuals resident in Italy are subject to a tax on the value of financial assets held outside of Italy. The taxable amount will be the fair market value of the financial assets (including Stock) on December 31 or on the last day the Stock were held (the tax is levied in proportion to the number of days the shares were held during the calendar year). The tax is assessed as part of the annual tax return.

Exhibit 10.3

MEXICO

Terms and Conditions

Plan Document Acknowledgement. By accepting the Restricted Stock Units, the Grantee acknowledges that he or she has received a copy of the Plan and the Agreement, including this Appendix, which the Grantee has reviewed. The Grantee acknowledges further that he or she accepts all the provisions of the Plan and the Agreement, including this Appendix. The Grantee also acknowledges that he or she has read and specifically and expressly approves the terms and conditions set forth in “Additional Acknowledgements” in this Appendix, which clearly provides as follows:

(1)The Grantee’s participation in the Plan does not constitute an acquired right;

(2)The Plan and the Grantee’s participation in it are offered by the Company on a wholly discretionary basis;

(3)The Grantee’s participation in the Plan is voluntary; and

(4)Neither the Company nor any Affiliates are responsible for any decrease in the value of the Award granted and/or Stock issued under the Plan.

Labor Law Policy and Acknowledgment

By accepting the Restricted Stock Units, the Grantee expressly recognizes that the Company, with registered offices at Riverside One, Sir John Rogerson’s Quay, Dublin 2, Dublin, Ireland D02 X576, is solely responsible for the administration of the Plan and that the Grantee’s participation in the Plan and acquisition of Stock do not constitute an employment relationship between the Grantee and the Company since the Grantee is participating in the Plan on a wholly commercial basis and his or her sole employer is Trinseo de Mexico, S. de R.L. de C.V., Trinseo Services de Mexico, S. de R.L. de C.V., or Altuglas Mexico S.A. de C.V. (together, “Trinseo Mexico”). Based on the foregoing, the Grantee expressly recognizes that the Plan and the benefits that he or she may derive from participating in the Plan do not establish any rights between the Grantee and the employer, Trinseo Mexico, and do not form part of the employment conditions and/or benefits provided by Trinseo Mexico, and any modification of the Plan or its termination shall not constitute a change or impairment of the terms and conditions of the Grantee’s employment.

The Grantee further understands that his or her participation in the Plan is as a result of a unilateral and discretionary decision of the Company; therefore, the Company reserves the absolute right to amend and/or discontinue the Grantee’s participation at any time without any liability to the Grantee.

Finally, the Grantee hereby declares that he or she does not reserve to him- or herself any action or right to bring any claim against the Company for any compensation or damages regarding any provision of the Plan or the benefits derived under the Plan, and the Grantee therefore grants a full and broad release to the Company, and its subsidiaries, branches, representative offices, shareholders, directors, officers, employees, agents, or legal representatives with respect to any claim that may arise.

Exhibit 10.3

Spanish Translation

Reconocimiento del Documento del Plan

Al aceptar las Unidades de Acciones Restringidas, el Beneficiario reconoce que ha recibido una copia del Plan y el Acuerdo, con inclusión de este Anexo, que el Beneficiario ha revisado. El Beneficiario reconoce, además, que acepta todas las disposiciones del Plan y en el Acuerdo, incluyendo este Anexo. El Beneficiario también reconoce que ha leído y que concretamente aprueba de forma expresa los términos y condiciones establecidos en la Sección “Reconocimientos Adicionales” de este Anexo, que claramente dispone lo siguiente:

(1)La participación del Beneficiario en el Plan no constituye un derecho adquirido;

(2)El Plan y la participación del Beneficiario en el Plan se ofrecen por la Compañía en su discrecionalidad total;

(3)Que la participación del Beneficiario en el Plan es voluntaria; y

(4)Ni la Compañía ni sus Afiliadas son responsables por la reducción del valor del Premio y/o Acciones Ordinarias emitidas bajo el Plan.

Política Laboral y Reconocimiento

Al aceptar las Unidades de Acciones Restringidas, el Beneficiario expresamente reconoce que la Compañía, con sus oficinas registradas y ubicadas en Riverside One, Sir John Rogerson’s Quay, Dublin 2, Dublin, Ireland D02 X576, es la única responsable por la administración del Plan y que la participación del Beneficiario en el Plan y en su caso la adquisición de Acciones no constituyen una relación de trabajo entre el Beneficiario y la Compañía, ya que el Beneficiario participa en el Plan en un marco totalmente comercial y su único patrón es Trinseo de Mexico, S. de R.L. de C.V., Trinseo Services de Mexico, S. de R.L. de C.V., o Altuglas Mexico S.A. de C.V. (juntos, “Trinseo Mexico”). Derivado de lo anterior, el Beneficiario expresamente reconoce que el Plan y los beneficios que pudieran derivar de la participación en el Plan no establecen derecho alguno entre el Beneficiario y el patrón, Trinseo Mexico, y no forma parte de las condiciones de trabajo y/o las prestaciones otorgadas por Trinseo Mexico, y que cualquier modificación al Plan o su terminación no constituye un cambio o desmejora de los términos y condiciones de la relación de trabajo del Beneficiario.

Asimismo, el Beneficiario reconoce que su participación en el Plan se ha resultado de una decisión unilateral y discrecional de la Compañía; por lo tanto, la Compañía se reserva el derecho absoluto de modificar y/o terminar la participación del Beneficiario en cualquier momento y sin responsabilidad alguna frente el Beneficiario.

Finalmente, el Beneficiario por este medio declara que no se reserva ninguna derecho o acción en contra de la Compañía por cualquier compensación o daños y perjuicios en relación de las disposiciones del Plan o de los beneficios derivados del Plan, y por lo tanto, el Beneficiario otorga el más amplio finiquito que en derecho proceda a la Compañía, y sus filiales, oficinas de representación, accionistas, directores, autoridades, empleados, agentes, o representantes legales en relación con cualquier demanda que pudiera surgir.

Exhibit 10.3

Notifications

Securities Law Notification.

The Restricted Stock Units granted, and any Stock acquired, under the Plan have not been registered with the National Register of Securities maintained by the Mexican National Banking and Securities Commission and cannot be offered or sold publicly in Mexico. In addition, the Plan, the Agreement and any other document relating to the Restricted Stock Units may not be publicly distributed in Mexico. These materials are addressed to the Grantee because of the Grantee’s existing relationship with the Company and any Affiliate, and these materials should not be reproduced or copied in any form. The offer contained in these materials does not constitute a public offering of securities but rather constitutes a private placement of securities addressed specifically to individuals who are present employees of Trinseo Mexico made in accordance with the provisions of the Mexican Securities Market Law, and any rights under such offering shall not be assigned or transferred.  

NETHERLANDS

Terms and Conditions

Waiver of Termination Rights.  In consideration of the grant of the Restricted Stock Units, the Grantee agrees that he or she waives any and all rights to compensation or damages as a result of any termination of employment for any reason whatsoever, insofar as those rights result or may result from (a) the loss or diminution in value of such rights or entitlements under the Plan, or (b) the Grantee ceases to have rights under, or ceasing to be entitled to any awards under the Plan as a result of such termination.

SINGAPORE

Terms and Conditions

Restriction on Sale of Shares of Stock.  To the extent the Restricted Stock Units vest within six (6) months of the Grant Date, the Grantee may not dispose of the Stock issued upon settlement of the Restricted Stock Units, or otherwise offer the Stock to the public, prior to the six (6)-month anniversary of the Grant Date, unless such sale or offer is made pursuant to the exemptions under Part XIII Division (1) Subdivision (4) (other than section 280) of the Securities and Futures Act (Chap. 289, 2006 Ed.) (“SFA”) and in accordance with any other applicable provision of the SFA.

Notifications

Securities Law Information. The Restricted Stock Units are being granted pursuant to the “QualifyingPerson”exemptionundersection273(1)(f)oftheSFA, under which it is exempt from the prospectus and registration requirements and is not made with a view to the underlying shares being subsequently offeredfor sale to any other part. The Plan has not been and will not be lodged or registered as a prospectus with the Monetary Authority of Singapore and is not regulated by any financial supervisory authority pursuant to any legislation in Singapore.

Director Notification. If the Grantee is a director (including alternate director, substitute associate and shadow director) of a Singapore subsidiary, the Grantee must notify the Singapore subsidiary

Exhibit 10.3

in writing within two (2) business days of (i) becoming the registered holder of or acquiring an interest (e.g., Restricted StockUnits,Stocks,etc.)intheCompanyoranyofitssubsidiary,orbecomingthealternate director, substitute director or shadow director (as the case may be), whichever occurs last, or (ii) any change in a previously disclosed interest (e.g., sale ofStock). If the Grantee is the chief executive officer (“CEO”) of a Singapore subsidiary and the above notification requirements are determined to apply to CEO of a Singapore subsidiary, the above notification requirements also may apply to the Grantee.

SPAIN

Terms and Conditions

Nature of Award. In accepting the grant of Restricted Stock Units, the Grantee acknowledges that he or she consents to participation in the Plan and has received a copy of the Plan.

The Grantee understands that the Company has unilaterally, gratuitously and discretionally decided to grant Restricted Stock Units under the Plan to individuals who may be employees of the Company or its Affiliates throughout the world. The decision is a limited decision that is entered into upon the express assumption and condition that any grant will not economically or otherwise bind the Company or any of its Affiliates over and above the specific terms of the Plan. Consequently, the Grantee understands that the Restricted Stock Units are granted on the assumption and condition thattheRestrictedStockUnitsandtheStockacquireduponlapseoftherestrictionsrelatingtothe Restricted Stock Units shall not become a part of any employment contract (either with the Company or any of its Affiliates) and shall not be considered a mandatory benefit, salary for any purposes (including severance compensation) or any other right whatsoever.

Further, the Grantee understands and agrees that, unless otherwise expressly provided for by the Company or set forth in the Agreement, the Restricted Stock Units will be cancelled without entitlement to any Stock if the Grantee ceases to be an eligible participant for any reason, including, but not limited to: resignation, disciplinary dismissal adjudged to be with cause, disciplinary dismissal adjudged or recognized to be without good cause (i.e., subject to a “despido improcedente”), material modification of the terms of employment under Article 41 of the Workers’ Statute, relocation under Article 40 of the Workers’ Statute, Article 50 of the Workers’ Statute, or under Article 10.3 of Royal Decree 1382/1985.  The Company, in its sole discretion, shall determine the date when the Grantee’s status as an eligible participant has terminated for purposes of the Restricted Stock Units.

In addition, the GranteeunderstandsthatthisgrantwouldnotbemadetotheGranteebutfortheassumptionsand conditions referred to above; thus, the Grantee acknowledges and freely accepts that should any or all of the assumptions be mistaken or should any of the conditions not be met for any reason, then any grant of Restricted Stock Units shall be null andvoid.

Notifications

Securities Law Information. No “offer of securities to the public,” within the meaning of Spanish law, has taken place or will take place in the Spanish territory in connection with the Plan or Restricted Stock Unit. The Plan, the Agreement (including this Appendix) and any other documents evidencing the grant of the Restricted Stock Units have not been, nor will they be,

Exhibit 10.3

registeredwiththeComisión Nacional del Mercado de Valores (theSpanishsecuritiesregulator), and none of those documents constitutes a public offeringprospectus.

Exchange Control Information. In the event that the Grantee is a Spanish resident and acquires Stock under the Plan, he or she must declare such acquisition to the Spanish Dirección General de Comercio e Inversiones (the “DGCI”), the Bureau for Commerce and Investments, which is a department of the Ministry of Economy and Competitiveness.  If the Grantee acquires Stock through the use of a Spanish financial institution, the institution will automatically make the declaration with the DGCI for the Grantee.  The Grantee must also declare ownership or sale of any Stock by filing a Form D-6 with the Directorate of Foreign Transactions each January while the Stock is owned.  However, if the value of the Stock acquired or sold during the year exceeds the applicable threshold (currently €1,502,530), the filing is due within one month after the acquisition or sale, as applicable.

Spanish residents are required to electronically declare to the Bank of Spain any securities accounts (including brokerage accounts held abroad), as well as the securities (including Stock acquired at vesting of the Restricted Stock Units) held in such accounts, and any transactions carried out with non-residents, if the value of the transactions for all such accounts during the prior tax year or the balances in such accounts as of December 31 of the prior tax year exceeds €1,000,000.

Foreign Asset / Account Reporting Information.  Spanish residents holding rights or assets (e.g., Stock, cash, etc.) in a bank or brokerage account outside of Spain with a value in excess of €50,000 per type of right or asset as of December 31 each year are required to report information on such rights and assets on his or her tax return for such year.  Stock acquired under the Plan constitute securities for purposes of this requirement, but unvested rights (e.g., Restricted Stock Units) are not considered assets or rights for purposes of this requirement.  After such shares or accounts are initially reported, the reporting obligation will apply for subsequent years only if the value of any previously reported shares or accounts increases by more than €20,000 as of each subsequent December 31, or if the Grantee sells Stock or cancels bank accounts that were previously reported.

SWITZERLAND

Notifications

Securities Law Information. Neither this document nor any other materials relating to the grant of Restricted Stock Units (i) constitutes a prospectus according to articles 35 et seq. of the Swiss Federal Act on Financial Services (“FinSA”) (ii) may be publicly distributed nor otherwise made publicly available in Switzerland to any person other than an employee of the Company or (iii) have been or will be filed with, approved or supervised by any Swiss reviewing body according to article 51 of FinSA or any Swiss regulatory authority, including the Swiss Financial Market Supervisory Authority (FINMA).

TAIWAN

Notifications

Securities Law Information.  The offer of participation in the Plan is available only for employees of the Company and its Affiliates and is not a public offer of securities by a Taiwanese

Exhibit 10.3

company.

Exchange Control Information. The Grantee may acquire and remit foreign currency (including proceeds from the sale of Stock) up to US$5,000,000 per year without justification. If the transaction amount is TWD500,000 or more in a single transaction, the Grantee must submit a ForeignExchangeTransactionForm.IfthetransactionamountisUS$500,000ormoreinasingle transaction, the Grantee must also provide supporting documentation to the satisfaction of the remitting bank.

TURKEY

Notifications

Securities Law Information. Under Turkish law, the Grantee is not permitted to sell any Stock under the Plan in Turkey. The Stock is currently traded on the New York Stock Exchange (NYSE), which is located outside Turkey, under the ticker symbol “TSE” and the Stock may be sold through this exchange.

In certain circumstances, you are permitted to acquire and sell securities on a non-Turkish stock exchange only through a financial intermediary licensed in Turkey. Therefore, the Grantee may be required to appoint a Turkish broker to assist with the sale of Stock acquired under the Plan. The Grantee should consult his or her personal legal advisor before selling any Stock acquired under the Plan to confirm the applicability of this requirement.

UNITED KINGDOM

Terms and Conditions

Tax Withholding and National Insurance Contributions Acknowledgement. Notwithstanding any provisions in the Agreement, the Grantee agrees that he or she is liable for all Tax-Related Items andherebycovenantstopayallsuchTax-RelatedItems,asandwhenrequestedbytheCompany, the Employer, or by Her Majesty’s Revenue and Customs (“HMRC”) or any other tax authority or other relevant authority. The Grantee also agrees to indemnify and keep indemnified the Company and the Employer against any Tax-Related Items that they are required to pay or withhold,orhavepaidorwillpay,toHMRC(oranyothertaxauthorityorotherrelevantauthority) on the Grantee’sbehalf.

Notwithstanding the foregoing, if the Grantee is a director or executive officer of the Company (within the meaning of Section 13(k) of the U.S. Securities Exchange Act of 1934, as amended), the terms of the immediately foregoing provision may not apply to the Grantee if the indemnification is viewed as a loan. In this case, if the amount of anyincometax due is notcollected from orpaid by the Grantee within ninety (90) days of the end of the U.K. tax yearin which an event giving rise to the indemnification described above occurs, the amount of any uncollected income taxmayconstitutean additional benefit to the Grantee on which additional income tax and national insurance contributions (“NICs”) may be payable. The Grantee will be responsible for reporting and paying any income tax due on this additional benefit directly to HMRC under the self-assessment regime and for payingtotheCompanyortheEmployer,asapplicable,anyemployeeNICsdueonthisadditional benefit, which the Company or the Employer may recover from the Grantee by any of the means referred to in Section 8 of theAgreement.

Exhibit 10.3

Exclusion of Claim. The Grantee acknowledges and agrees that the Grantee will have no entitlement to compensation or damages insofar as such entitlement arises or may arise from the Grantee’s ceasing to have rights under or to be entitled to the Restricted Stock Units, whether or not as a result of termination of Grantee’s Employment (whether the termination is in breach of contractorotherwise),orfromthelossordiminutioninvalueoftheRestrictedStockUnits.Upon the grant of the Restricted Stock Units, the Grantee shall be deemed to have waived irrevocably any suchentitlement.

***

EX-10.4

Exhibit 10.4

Name:

Target Number of PSUs subject to Vesting and Performance Conditions:

Date of Grant:

Trinseo PLC

Amended & Restated 2014 Omnibus Incentive Plan

Performance Award Stock Unit Agreement

This agreement (this “Agreement”) evidences an award (the “Award”) of restricted stock units subject to performance conditions (hereinafter referred to as Performance Award Stock Units or “PSUs”) granted by Trinseo PLC (the “Company”) to the undersigned (the “Grantee”) pursuant to the Trinseo PLC Amended & Restated 2014 Omnibus Incentive Plan (as amended from time to time, the “Plan”), which is incorporated herein by reference.

1.Grant of PSUs.  On the date of grant set forth above (the “Grant Date”) the Company granted to the Grantee an award consisting of the right to receive, on the terms provided herein and in the Plan and the performance conditions specified in Schedule A, one share of Stock with respect to each PSU forming part of the Award, in each case, subject to adjustment pursuant to Section 7 of the Plan in respect of transactions occurring after the date hereof.

The grant of the PSUs is a one-time benefit and does not create any contractual or other right for the Grantee to receive a grant of PSUs or benefits in lieu of PSUs in the future.

The Award shall not be interpreted to bestow upon the Grantee any equity interest or ownership in the Company or any Affiliate prior to the date on which the Company delivers shares of Stock to the Grantee (if any). The Grantee is not entitled to vote any shares of Stock by reason of the granting of this Award or to receive or be credited with any dividends declared and payable on any share of Stock prior to the date on which any such share is delivered to the Grantee hereunder.  The Grantee shall have the rights of a shareholder only as to those shares of Stock, if any, that are delivered under this Award.

2.Meaning of Certain Terms.  Except as otherwise defined herein, all capitalized terms used herein have the same meaning as in the Plan.  

3.Dividend Equivalents.  During the period beginning on the Grant Date and ending on the date that shares of Stock are issued in settlement of vested PSUs, the Grantee will accrue dividend equivalents on the PSUs (ultimately settled after adjustment for actual performance) equal to any cash dividend or cash distribution that would have been paid on the PSU had that PSU been an issued and outstanding share of Stock on the record date for the dividend or distribution. Such accrued dividend equivalents (i) will vest and become payable upon the same terms and at the same time of settlement as the PSU  to which they relate (and will be payable with respect to any shares of Stock that are issued or that are withheld pursuant to Section 9 in order to satisfy Grantee’s Tax-Related Items), (ii) will be denominated and payable solely in cash and paid in such manner as the Company deems appropriate, and (iii) will not bear or accrue interest. Dividend equivalent payments, at settlement, will be net of applicable federal, state, local and foreign income and social insurance withholding taxes as provided in Section 9. Upon the forfeiture of the PSUs, any accrued dividend equivalents attributable to such PSUs will also be forfeited.

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Exhibit 10.4

4.Vesting, etc.  

(a)Except as otherwise provided in this section, both performance and service vesting requirements must be satisfied before the Grantee can vest in the PSUs. With certain exceptions noted below, the Grantee will vest in the PSUs under this Agreement only if the Grantee’s Employment continues through the third anniversary of the Grant Date (“Service Vesting Date”) and the Company achieves the performance targets specified in Schedule A. The number of PSUs that will vest will be equal to the number of Banked Units earned pursuant to Schedule A as of the Service Vesting Date. Except as provided in sections (b) and (c) below, if the Grantee’s Employment with the Company terminates for any reason prior to the Service Vesting Date, the Award will be automatically and immediately forfeited upon such termination. See Schedule 1 for an example of vesting of Banked Units.

(b)If the Grantee’s Employment terminates due to his or her Retirement (as defined below), death or Permanent Disability, in each case, prior to the Service Vesting Date, the Award, to the extent then outstanding, will be treated as follows:

i. If the Grantee’s Employment terminates as a result of the Grantee’s Retirement (as defined below), upon such termination, the Grantee will be deemed to have met the service vesting requirements under this Award and will be eligible to receive a number of PSUs equal to (X) multiplied by (Y), where: (X) equals the total number Banked Units to which the Grantee would be entitled based upon actual performance during each Performance Period as described in Schedule A, and (Y) is the ratio, the numerator of which is the number of full months occurring between the Grant Date and the date of Grantee’s Retirement, and the denominator of which is thirty-six (36). For purposes hereunder, “Retirement” means a retirement from active Employment after the Grantee has attained age 55 with at least 10 years of continuous service with the Company, or its predecessor entity, The Dow Chemical Company, or any of its subsidiaries, or as defined in the Grantee’s employment or other agreement with the Company.

ii. If the Grantee’s Employment is terminated due to his or her death or by the Company due to his or her Permanent Disability, upon such termination, the Grantee will be eligible to receive a number of PSUs equal to (X) multiplied by (Y), where: (X) equals the total number of Eligible Units to which the Grantee would be entitled based upon Target performance during each Performance Period as described in the performance matrix set forth in Schedule A, and (Y) is the ratio, the numerator of which is the number of full months occurring between the Grant Date and the date of Grantee’s death or date of termination due to Permanent Disability, and the denominator of which is thirty-six (36).

(c)If, within the twenty-four (24)-month period following the occurrence of a Change in Control (as defined below), the Grantee’s Employment is terminated by the Company other than for Cause or, if the Grantee is otherwise subject to an effective employment or other individual agreement with the Company that provides the Grantee with the ability to terminate his or her employment for “good reason,” by the Grantee for “good reason” (with such term having the meaning ascribed thereto in the employment or other individual agreement, if any, between the Grantee and the Company for so long as such agreement is in effect), upon such termination, the Award, to the extent then outstanding, and regardless of whether the award is to be settled in

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Exhibit 10.4

shares of another entity, will result in truncated Performance Periods used to measure the performance criteria (to the extent measurable). The Performance Periods will be deemed to end on the effective date of the Change in Control and a determination of performance as provided in Schedule A will be made using the revised Performance Periods, though the amount determined for performance will at least equal the “Target” performance level for the truncated Performance Periods as set forth in the table in Schedule A.

For purposes of this Agreement, “Change in Control” means the first to occur of any of the following events:

i. an event in which any “person,” as such term is used in Sections 13(d) and 14(d) of the U.S. Securities Exchange Act of 1934, as amended (the “1934 Act”) (other than (A) the Company, (B) any subsidiary of the Company, (C) any trustee or other fiduciary holding securities under an employee benefit plan of the Company or of any subsidiary of the Company, and (D) any company owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as their ownership of stock of the Company), is or becomes the “beneficial owner” (as defined in Section 13(d) of the 1934 Act), together with all affiliates and associates (as such terms are used in Rule 12b-2 of the General Rules and Regulations under the 1934 Act) of such person, directly or indirectly, of securities of the Company representing 40% or more of the combined voting power of the Company’s then outstanding securities;

ii. the consummation of the merger or consolidation of the Company with any other company, other than (i) a merger or consolidation which would result in the voting securities of the Company outstanding immediately prior thereto continuing to represent (either by remaining outstanding or by being converted into voting securities of the surviving entity), in combination with the ownership of any trustee or other fiduciary holding securities under an employee benefit plan of the Company or any subsidiary of the Company, more than 50% of the combined voting power of the voting securities of the Company or such surviving entity outstanding immediately after such merger or consolidation and (ii) a merger or consolidation effected to implement a recapitalization of the Company (or similar transaction) after which no “person” “beneficially owns” (with the determination of such “beneficial ownership” on the same basis as set forth in clause (1) of this definition) securities of the Company or the surviving entity of such merger or consolidation representing 50% or more of the combined voting power of the securities of the Company or the surviving entity of such merger or consolidation; or

iii. the complete liquidation of the Company or the sale or disposition by the Company of all or substantially all of the Company’s assets.

Notwithstanding the foregoing, to the extent any amount constituting “nonqualified deferred compensation” subject to Section 409A would become payable under the Award by reason of a Change in Control, it shall become payable only if the event or circumstances constituting the Change in Control would also constitute a change in the ownership or effective control of the Company, or a change in the ownership of a substantial portion of the Company’s assets, within the meaning of subsection (a)(2)(A)(v) of Section 409A and the Treasury Regulations thereunder.

-3-

Exhibit 10.4

5.Delivery of Stock.  Subject to Section 9(b), the Company shall, as soon as practicable following the vesting of the PSUs or any portion thereof as provided in Section 4(a), (b) or (c) of this Agreement (but in no event later than thirty (30) days following the date on which such PSUs, or any portion thereof, vest) effect delivery of the Stock with respect to such vested PSUs, or any portion thereof, to the Grantee (or, in the event of the Grantee’s death, to the Grantee’s beneficiary, which for purposes hereunder shall be (a) if permitted by the Administrator, the person(s) who has been designated by the Grantee in writing in a form and manner acceptable to the Administrator to receive the Award in the event of the Grantee’s death or (b) in the event no beneficiary designation has been made by the Grantee, the Grantee’s estate). No Stock will be issued pursuant to this Award unless and until the Compensation Committee completes the written certification set forth in Section 6 below and all legal requirements applicable to the issuance or transfer of such Stock have been complied with to the satisfaction of the Administrator, including, the for the avoidance of doubt to the extent required by Irish law, the payment by the Grantee to the Company of an amount in cash equal to the aggregate par value of the shares of Stock to be delivered in respect of the vested PSUs on, or within thirty (30) days of, the settlement of shares of Stock. The actual amount the Grantee will be required to pay will be determined at the time that the Award is settled with shares of Stock.

6.Forfeiture; Recovery of Compensation. By accepting the Award the Grantee expressly acknowledges and agrees that his or her rights (and those of any permitted transferee) under the Award or to any Stock acquired under the Award or any proceeds from the disposition thereof, are subject to Section 6(a)(5) of the Plan (including any successor provision). Without limiting the foregoing, the Administrator may recover Performance Award Stock Units, or shares granted upon settlement of Performance Award Stock Units, in accordance with the Company’s Policy for Recoupment of Incentive Compensation (as may be amended from time to time) or as otherwise required by applicable law or applicable stock exchange listing standards. Nothing in the preceding sentence shall be construed as limiting the general application of Section 11 of this Agreement.

7.Nontransferability.  Neither the Award nor the PSUs may be transferred except at death in accordance with Section 6(a)(3) of the Plan.

8.Responsibility for Taxes & Withholding.  Regardless of any action the Company or any of its Affiliates takes with respect to any or all income tax, social insurance, payroll tax, payment on account or other tax-related items related to the Grantee’s participation in the Plan and legally applicable to the Grantee (“Tax-Related Items”), the Grantee acknowledges that the ultimate liability for all Tax-Related Items is and remains the Grantee’s responsibility and may exceed the amount actually withheld by the Company or any of its Affiliates.  The Grantee further acknowledges that the Company and/or its Affiliates (a) make no representations or undertakings regarding the treatment of any Tax-Related Items in connection with any aspect to the PSUs, including, but not limited to, the grant, vesting or settlement of the PSUs, the issuance of Stock upon settlement of the PSUs, the subsequent sale of Stock acquired pursuant to such issuance and the receipt of any dividends and/or dividend equivalents; and (b) do not commit to and are under no obligation to structure the terms of any Award to reduce or eliminate Grantee’s liability for Tax-Related Items or achieve any particular tax result.  Further, if the Grantee becomes subject to tax in more than one jurisdiction between the date of grant and the date of any relevant taxable event, the Grantee acknowledges that Company and/or its Affiliates may be required to withhold or account for Tax-Related Items in more than one jurisdiction.

Prior to any relevant taxable or tax withholding event, as applicable, the Grantee will pay or make adequate arrangements satisfactory to the Company and/or its Affiliates to satisfy all Tax-Related Items.  

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Exhibit 10.4

In this regard, the Grantee authorizes the Company and/or its Affiliates, or their respective agents, at their discretion, to satisfy the obligations with regard to all Tax-Related Items by one or a combination of the following:

(i)withholding from the Grantee’s wages/salary or other cash compensation paid to the Grantee by the Company and/or its Affiliates; or

(ii) withholding from proceeds of the Stock acquired upon vesting/settlement of the PSUs either through a voluntary sale or through a mandatory sale arranged by the Company (on Grantee’s behalf pursuant to this authorization); or

(iii) withholding in Stock to be issued upon vesting/settlement of the PSUs provided, however, that if the Grantee is a Section 16 officer of the Company under the U.S. Securities and Exchange Act of 1934, as amended, then the Company will withhold in shares of Stock upon the relevant taxable or tax withholding event, as applicable, unless the use of such withholding method is problematic under applicable tax or securities law or has materially adverse accounting consequences, in which case, the obligation for Tax-Related Items may be satisfied by one or a combination of methods (i) and (ii) above.

To avoid negative accounting treatment, the Company and/or its Affiliates may withhold or account for Tax-Related Items by considering applicable minimum statutory withholding amounts or other applicable withholding rates.  If the obligation for Tax-Related Items is satisfied by withholding in Stock, for tax purposes, the Grantee is deemed to have been issued the full number of shares of Stock attributable to the vested PSUs, notwithstanding that a number of share are held back solely for the purpose of paying the Tax-Related Items due as a result of any aspect of the Grantee’s participation in the Plan.

The Grantee shall pay to the Company and/or its Affiliates any amount of Tax-Related Items that the Company and/or its Affiliates may be required to withhold or account for as a result of the Grantee’s participation in the Plan that will not for any reason be satisfied by the means previously described. The Company may refuse to issue or deliver the Stock or the proceeds of the sale of Stock if the Grantee fails to comply with the Grantee’s obligations in connection with the Tax-Related Items.

By accepting this grant of PSUs, the Grantee expressly consents to the methods of withholding Tax-Related Items by the Company and/or its Affiliates as set forth herein, including the withholding of Stock and the withholding from the Grantee’s wages/salary or other amounts payable to the Grantee.  All other Tax-Related Items related to the PSUs and any Stock delivered in satisfaction thereof are the Grantee’s sole responsibility.

9.Other Tax Matters.

(a) The Grantee expressly acknowledges that because this Award consists of an unfunded and unsecured promise by the Company to deliver Stock in the future, subject to the terms hereof, it is not possible to make a so-called “83(b) election” under U.S. federal tax laws with respect to the Award.

(b) If, at the time of the Grantee’s termination of employment, the Grantee is a “specified employee,” as defined below, to the extent required by Section 409A, any and all amounts payable on account of the Grantee’s separation from service that constitute deferred

-5-

Exhibit 10.4

compensation and would (but for this provision) be payable within six (6) months following the date of termination, shall instead be paid on the next business day following the expiration of such six (6) month period or, if earlier, upon the Grantee’s death.  For purposes of this Agreement, all references to “termination of employment” and correlative phrases shall be construed to require a “separation from service” (as defined in Treasury Regulations section 1.409A-1(h) after giving effect to the presumptions contained therein), and the term “specified employee” means an individual determined by the Company to be a specified employee under Treasury Regulation section 1.409A-1(i).  Each payment made under this Agreement shall be treated as a separate payment and the right to a series of installment payments under this Agreement is to be treated as a right to a series of separate payments.

10.Effect on Employment.  Neither the grant of the PSUs, nor the delivery of Stock upon vesting of any portion thereof, will give the Grantee any right to be retained in the employ or service of the Company or any of its Affiliates, affect the right of the Company or any of its Affiliates to discharge or discipline such Grantee at any time, or affect any right of such Grantee to terminate his or her Employment at any time.

11.Acknowledgements.  By accepting the Award, the Grantee agrees to be bound by, and agrees that the Award and the PSUs are subject in all respects to, the terms of the Plan.  The Grantee further acknowledges and agrees that (i) this Agreement may be executed in two or more counterparts, each of which shall be an original and all of which together shall constitute one and the same instrument, (ii) this agreement may be executed and exchanged using facsimile, portable document format (PDF) or electronic signature, which, in each case, shall constitute an original signature for all purposes hereunder and (iii) such signature by the Company will be binding against the Company and will create a legally binding agreement when this Agreement is countersigned by the Grantee.  

12.Authorization to Release and Transfer Necessary Personal Information. The Grantee hereby explicitly and unambiguously consents to the collection, use and transfer, in electronic or other form, of his or her personal data by and among, as applicable, the Company and the Affiliates for the exclusive purpose of implementing, administering and managing the Grantee’s participation in the Plan. The Grantee understands that the Company and the Affiliates may hold certain personal information about the Grantee including, but not limited to, the Grantee’s name, home address and telephone number, date of birth, social security number (or any other social or national identification number), salary, nationality, job title, number of PSUs and/or Stock held and the details of all PSUs or any other entitlement to Stock awarded, cancelled, vested, unvested or outstanding for the purpose of implementing, administering and managing the Grantee’s participation in the Plan (the “Data”).  The Grantee understands that the Data may be transferred to the Company or any of the Affiliates, or to any third parties assisting in the implementation, administration and management of the Plan, that these recipients may be located in the Grantee’s country or elsewhere, and that any recipient’s country (e.g., the United States) may have different data privacy laws and protections than the Grantee’s country.  The Grantee understands that he or she may request a list with the names and addresses of any potential recipients of the Data by contacting his or her local human resources representative.  The Grantee authorizes the recipients to receive, possess, use, retain and transfer the Data, in electronic or other form, for the sole purpose of implementing, administering and managing his or her participation in the Plan, including any requisite transfer of such Data to a broker or other third party assisting with the administration of PSUs under the Plan or with whom Stock acquired pursuant to the vesting of the PSUs or cash from the sale of such Stock may be deposited.  Furthermore, the Grantee acknowledges and understands that the transfer of the Data to the Company or the Affiliates or to any third parties is

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Exhibit 10.4

necessary for his or her participation in the Plan.  The Grantee understands that Data will be held only as long as is necessary to implement, administer and manage his or her participation in the Plan.  The Grantee understands that he or she may, at any time, view the Data, request additional information about the storage and processing of the Data, require any necessary amendments to the Data or refuse or withdraw the consents herein by contacting his or her local human resources representative in writing.  The Grantee further acknowledges that withdrawal of consent may affect his or her ability to vest in or realize benefits from the PSUs, and his or her ability to participate in the Plan.  For more information on the consequences of refusal to consent or withdrawal of consent, the Grantee understands that he or she may contact his or her local human resources representative.

Finally, upon request of the Company or the Grantee’s employer (the “Employer”), the Grantee agrees to provide an executed data privacy consent form (or any other agreements or consents that may be required by the Company and/or the Employer) that the Company and/or the Employer may deem necessary to obtain from the Grantee for the purpose of administering the Grantee’s participation in the Plan in compliance with the data privacy laws in the Grantee’s country, either now or in the future. The Grantee understands and agrees that the Grantee will not be able to participate in the Plan if the Grantee fails to provide any such consent or agreement requested by the Company and/or the Employer.

13.Electronic Delivery and Execution.  The Grantee hereby consents and agrees to electronic delivery of any documents that the Company may elect to deliver (including, but not limited to, plan documents, prospectus and prospectus supplements, grant or award notifications and agreements, account statements, annual and quarterly reports, and all other forms of communications) in connection with this and any other Award made or offered under the Plan. The Grantee understands that, unless revoked by the Grantee by giving written notice to the Company pursuant to the Plan, this consent will be effective for the duration of the Agreement. The Grantee also understands that he or she will have the right at any time to request that the Company deliver written copies of any and all materials referred to above. The Grantee hereby consents to any and all procedures the Company has established or may establish for an electronic signature system for delivery and acceptance of any such documents that the Company may elect to deliver, and agree that his or her electronic signature is the same as, and will have the same force and effect as, his or her manual signature. The Grantee consents and agrees that any such procedures and delivery may be affected by a third party engaged by the Company to provide administrative services related to the Plan.

14.Appendix.  Notwithstanding any provision of the Agreement to the contrary, this PSU grant and the Stock acquired under the Plan shall be subject to any and all special terms and provisions as set forth in the Appendix, if any, for the Grantee’s country of residence (and country of employment, if different). Moreover, if the Grantee relocates to one of the countries included in the Appendix, the additional terms and conditions for such country will apply to the Grantee, to the extent the Company determines that the application of such terms and conditions is necessary or advisable for legal or administrative reasons. The Appendix constitutes part of the Agreement.

15.Severability.  The provisions of this Agreement are severable and if any one or more provisions are determined to be illegal or otherwise unenforceable, in whole or in part, the remaining provisions shall nevertheless be binding and enforceable.

[Signature page follows.]

-7-

IN WITNESS WHEREOF, the Company has caused this Agreement to be executed by its duly authorized officer.

TRINSEO PLC

By:

Name:

Title:

Dated:

Acknowledged and Agreed:

By:

Signature Page to Performance Stock Unit Agreement

Exhibit 10.4

SCHEDULE A

The number of PSUs to which the Grantee will be entitled if the Grantee satisfies the applicable service requirements will be calculated by the Committee (or sub-committee thereof) based on the Company’s “Relative Total Stockholder Return” (as defined below). Specifically, if the Grantee satisfies the applicable service requirements, the Committee shall calculate the number of Banked Units earned during each Performance Period by (x) multiplying the Grantee’s Target Number of PSUs by the applicable percentage set forth in each of section (a)-(d) below for each Performance Period (the “Eligible Units”), and (y) multiplying the number of Eligible Units by the applicable percentage determined as set forth below based on the Company’s Relative Total Stockholder Return results for the specified Performance Period. As noted in the Terms and Conditions to this Agreement, special rules apply under certain circumstances, such as death, Permanent Disability, Change in Control and Retirement.

For purposes of this Agreement, the term “Banked Unit” means a PSU that has been tentatively credited for the Grantee’s benefit based on the Grantee’s service through a specified date and the satisfaction of applicable performance conditions as provided below, provided however, that a Banked Unit will not represent a vested PSU except to the extent provided in Section 4. Shares associated with vested PSUs shall only become deliverable, in accordance with Section 5.

For purposes of this Agreement, the term “Performance Period” shall mean the following periods, and Banked Units shall be calculated as follows:

(a) Calendar Year 2024. Subject to the Grantee’s continued Employment by the Company or any of its Affiliates through December 31, 2024, 15% of the Target Number of PSUs shall become Banked Units, subject to adjustment based upon the Company’s Total Stockholder Return (as defined below) relative to the Total Stockholder Return of the Comparator Group (as defined below) from January 1, 2024 until December 31, 2024 in accordance with the Relative Total Stockholder Return Table in Schedule A.

(b) Calendar Year 2025. Subject to the Grantee’s continued Employment by the Company or any of its Affiliates through December 31, 2025, 15% of the Target Number of PSUs shall become Banked Units, subject to adjustment based upon the Company’s Total Stockholder Return (as defined below) relative to the Total Stockholder Return of the Comparator Group (as defined below) from January 1, 2025 until December 31, 2025 in accordance with the Relative Total Stockholder Return Table in Schedule A.

(c) Calendar Year 2026. Subject to the Grantee’s continued Employment by the Company or any of its Affiliates through December 31, 2026, 15% of the Target Number of PSUs shall become Banked Units, subject to adjustment based upon the Company’s Total Stockholder Return (as defined below) relative to the Total Stockholder Return of the Comparator Group (as defined below) from January 1, 2026 until December 31, 2026 in accordance with the Relative Total Stockholder Return Table in Schedule A.

(d) Cumulative Period 2024–2026. Subject to the Grantee’s continued Employment by the Company or any of its Affiliates through December 31, 2026, 55% of the Target Number of PSUs shall become Banked Units, subject to adjustment based upon the Company’s Total Stockholder Return (as defined below) relative to the Total Stockholder Return of the Comparator Group (as

Exhibit 10.4

defined below) from January 1, 2024 until December 31, 2026 in accordance with the Relative Total Stockholder Return Table.

The following table shall apply for calculating this Award:

Relative Total Stockholder Return Over Each Performance Period

Performance Level	Payout Level (% of Target)	Relative TSR Ranking
Maximum*	200%	75th percentile
Target	100%	50th percentile
Threshold	50%	25th percentile

The maximum percentage by which the Grantee’s Target Number of PSUs is multiplied cannot exceed 200% and no PSUs shall become Banked Units unless the Company’s Relative Total Stockholder Return performance for the specified period is equal to or greater than the level required to earn an award of 50% of the Eligible Units for such period. Notwithstanding the above: (I) in the event that the Company’s Total Stockholder Return during any Performance Period is negative, the number of vested PSUs due to the Grantee cannot exceed 100% of the Grantee’s Eligible Units for such period, and (II) the fair market value of the total number of shares of Stock due to be delivered to the Grantee following the vesting of all Banked Units pursuant to Section 4 of the Agreement (determined on the certification date of the Award) shall not exceed 300% of the total fair market value of the shares of Stock attributable to the Eligible Units (determined as of the Grant Date).

If the Company’s Relative Total Stockholder Return performance falls between designated levels of performance set forth in the above table, the percentage by which the Grantee’s Eligible Units is multiplied will be calculated by linear interpolation.

Relative Total Stockholder Return shall mean the percentile ranking of the Company’s Total Stockholder Return (as defined below) measured relative to each company in the Comparator Group’s Comparator Total Stockholder Return (as defined below) during each Performance Period. The “Comparator Group” shall consist of all Chemical and Basic Materials companies in the S&P 600 Small Cap Index at the start of each Performance Period. Companies in the Comparator Group that are acquired during a Performance Period and are no longer publicly traded at the end of a Performance Period will be removed from the Comparator Group for such Performance Period. Any company in the Comparator Group which declares bankruptcy, is liquidated or is otherwise delisted during the relevant Performance Period shall remain in the Comparator Group and such company’s performance shall be considered to have been at the bottom of the Comparator Group. The Comparator Group companies for the initial Performance Period are set forth on the next page.

The percentile ranking of the Company’s Relative Total Stockholder Return shall be that fraction which is calculated by dividing the number of companies in the Comparator Group whose Comparator Total Stockholder Return performance is exceeded by the Company (based on the Total Stockholder Return) by the total number of companies in the Comparator Group.

Except as noted in this Schedule A, no adjustments for extraordinary items shall be made when calculating Relative Total Stockholder Return.

Exhibit 10.4

Total Stockholder Return shall mean the percentage rate of growth during each relevant Performance Period of an investment of $1,000 in shares of Stock on the first day of each such Performance Period, assuming reinvestment of all dividends paid during each such Performance Period and adjusted in an equitable manner for any material stock splits, reverse stock splits or similar transactions.

Comparator Total Stockholder Return for an applicable company in the Comparator Group shall mean the percentage rate of growth during each relevant Performance Period of an investment of $1,000 in shares of the common stock of the applicable company in the Comparator Group on the first day of each Performance Period, assuming reinvestment of all dividends paid during each Performance Period and adjusted in an equitable manner for any material stock splits, reverse stock splits or similar transactions.

Total Stockholder Return for the Company or any applicable company in the Comparator Group shall be measured based on the average fair market value (“FMV”) of the applicable share of stock for the thirty (30) trading days following the commencement of the Performance Period as compared to the average FMV of the same shares for the last thirty (30) trading days prior to the Service Vesting Date.  The FMV of the Company’s Stock or of a share of the common stock of a company in the Comparator Group shall mean the closing price of a share of that stock on the New York Stock Exchange or other national stock exchange on which that stock is actively traded for that date as reported in the Wall Street Journal, Eastern Edition or such other standard reference service as the Committee may select.

Exhibit 10.4

Example of Banked Vesting over Performance Period

I. Grantee’s Employment continues through the Service Vesting Date

A. Company achieves at least Threshold Relative Shareholder Return
for all Performance Periods

Hire Date:	1-Jan-2000				Retirement Date:		n.a.
Target Units Granted:	12,000				Grant Date:		21-Feb-2024
Grant Year	Performance Period	Weight	Units Eligible	Payout1	Weighted Payout	Banked Units	Forfeited Units	Shares Delivered (at vest)
2024	2024	15%	1,800	100%	15.0%	1,800	0	1,800
	2025	15%	1,800	120%	18.0%	2,160	0	2,160
	2026	15%	1,800	180%	27.0%	3,240	0	3,240
	2024-2026	55%	6,600	200%	110.0%	13,200	0	13,200
	Totals	100%	12,000		170.0%	20,400	0	20,400

B. Company does not achieve at Threshold Relative Shareholder Return
for two Performance Periods

Hire Date:	1-Jan-2000				Retirement Date:			n.a.
Target Units Granted:	12,000					Grant Date:		21-Feb-2024
Grant Year	Performance Period	Weight	Units Eligible	Payout1	Weighted Payout		Banked Units	Forfeited Units	Shares Delivered (at vest)
2024	2024	15%	1,800	0%	0.0%		0	0	0
	2025	15%	1,800	60%	9.0%		1,080	0	1,080
	2026	15%	1,800	0%	0.0%		0	0	0
	2024-2026	55%	6,600	50%	27.5%		3,300	0	3,300
	Totals	100%	12,000		36.5%		4,380	0	4,380

Exhibit 10.4

II. Grantee Retires in December 2025

A. Company achieves at least Threshold Relative Shareholder Return
for all Performance Periods

Hire Date:	1-Jan-2000				Retirement Date:			31-Dec-2025
Target Units Granted:	12,000					Grant Date:		21-Feb-2024
Grant Year	Performance Period	Weight	Units Eligible	Payout1	Weighted Payout		Banked Units	Forfeited Units	Shares Delivered (at vest)
2024	2024	15%	1,800	100%	15.0%		1,800	700	1,100
	2025	15%	1,800	120%	18.0%		2,160	840	1,320
	2026	15%	1,800	180%	27.0%		3,240	1,260	1,980
	2024-2026	55%	6,600	200%	110.0%		13,200	5,133	8,067
	Totals	100%	12,000		170.0%		20,400	7,933	12,467

B. Company does not achieve at least Threshold Relative Shareholder Return
for two Performance Periods

Hire Date:	1-Jan-2000				Retirement Date:		31-Dec-2025
Target Units Granted:	12,000				Grant Date:		21-Feb-2024
Grant Year	Performance Period	Weight	Units Eligible	Payout1	Weighted Payout	Banked Units	Forfeited Units	Shares Delivered (at vest)
2024	2024	15%	1,800	0%	0.0%	0	0	0
	2025	15%	1,800	60%	9.0%	1,080	420	660
	2026	15%	1,800	0%	0.0%	0	0	0
	2024-2026	55%	6,600	50%	27.5%	3,300	1,283	2,017
	Totals	100%	12,000		36.5%	4,380	1,703	2,677

Exhibit 10.4

Comparator Group (Performance Peer Group)

for initial Performance Period

(updated as set forth in Schedule A)

Name	Ticker	Industry
Advansix Inc.	ASIX	Commodity Chemicals
Alpha Metallurgical Resources Inc	AMR	Steel
Arcadium Lithium plc	ALTM	Lithium Chemicals
ATI Inc.	ATI	Steel
Balchem Corporation	BCPC	Specialty Chemicals
Carpenter Technology Corporation	CRS	Steel
Century Aluminum Company	CENX	Aluminum
Clearwater Paper Corporation	CLW	Paper Products
Compass Minerals International, Inc.	CMP	Diversified Metals & Mining
Hawkins, Inc.	HWKN	Commodity Chemicals
Haynes International, Inc.	HAYN	Steel
H.B. Fuller Company	FUL	Specialty Chemicals
Ingevity Corp	NGVT	Specialty Chemicals
Innospec Inc.	IOSP	Specialty Chemicals
Kaiser Aluminum Corporation	KALU	Aluminum
Koppers Holdings Inc.	KOP	Commodity Chemicals
Materion Corporation	MTRN	Diversified Metals & Mining
Mativ Holdings, Inc.	MATV	Commodity Chemicals
Mercer International Inc.	MERC	Paper Products
Myers Industries Inc	MYE	Metal, Glass & Plastic Containers
Minerals Technologies Inc.	MTX	Specialty Chemicals
Myers Industries, Inc.	MYE	Metal, Glass & Plastic Containers
O-I Glass, Inc.	OI	Metal, Glass & Plastic Containers
Olympic Steel, Inc.	ZEUS	Steel
Quaker Chemical Corporation	KWR	Specialty Chemicals
Sealed Air Corp	SEE	Paper & Plastic Packaging Products & Materials
Sensient Technologies Corp	SXT	Specialty Chemicals
Stepan Company	SCL	Specialty Chemicals
SunCoke Energy, Inc.	SXC	Steel
Sylvamo Corporation	SLVM	Paper Products
TimkenSteel Corporation	TMST	Steel
Warrior Met Coal, Inc.	HCC	Steel
Worthington Steel Inc	WS	Steel

Exhibit 10.4

COUNTRY APPENDIX

ADDITIONAL TERMS AND CONDITIONS TO

PERFORMANCE AWARD STOCK UNIT AGREEMENT

This Country Appendix (“Appendix”) includes the following additional terms and conditions that govern the Grantee’s PSU Award for all Grantees that reside and/or work outside of the United States.

Notifications

This Appendix also includes information regarding exchange controls and certain other issues of which the Grantee should be aware with respect to the Grantee’s participation in the Plan. The information is based on the securities, exchange control and other laws in effect in the respective countries as of December 2021. Such laws are often complex and change frequently. As a result, the Company strongly recommends that the Grantee not rely on the information in this Appendix as the only source of information relating to the consequences of the Grantee’s participation in the Plan because the information may be out of date at the time that the PSUs vest, or Stock is delivered in settlement of the PSUs, or the Grantee sells any Stock acquired under the Plan.

In addition, the information contained herein is general in nature and may not apply to the Grantee’s particular situation, and none of the Company, its Affiliates, nor the Administrator is in a position to assure the Grantee of a particular result. Accordingly, the Grantee is advised to seek appropriate professional advice as to how the relevant laws in the Grantee’s country of residence and/or work may apply to the Grantee’s situation.

Finally, if the Grantee transfers employment after the Grant Date, or is considered a resident of another country for local law purposes following the Grant Date, the notifications contained herein may not be applicable to the Grantee, and the Administrator shall, in its discretion, determine to what extent the terms and conditions contained herein shall be applicable to the Grantee.

Terms and Conditions Applicable to All Non-U.S. Jurisdictions

English Language.  The Grantee acknowledges and agrees that it is the Grantee’s express intent that this Agreement, the Plan and all other documents, rules, procedures, forms, notices and legal proceedings entered into, given or instituted pursuant to the PSU Award, be drawn up in English. If the Grantee has received this Agreement, the Plan or any other rules, procedures, forms or documents related to the PSU Award translated into a language other than English, and if the meaning of the translated version is different than the English version, the English version will control.

Compliance with Law.  Notwithstanding any other provision of the Plan or this Agreement, unless there is an exemption from any registration, qualification or other legal requirement applicable to the Stock, the Company shall not be required to deliver any shares issuable upon settlement of the PSU prior to the completion of any registration or qualification of the shares under any local, state, federal or foreign securities or exchange control law or under rulings or regulations of the U.S. Securities and Exchange Commission (“SEC”) or of any other governmental regulatory body, or prior to obtaining any approval or other clearance from any local, state, federal or foreign governmental agency, which registration, qualification or approval the Company shall, in its absolute discretion, deem necessary or advisable. The Grantee understands that the Company is under no obligation to register or qualify the shares with the SEC or any state or foreign securities commission or to seek approval or clearance from any governmental authority for the issuance or sale of the shares.  Further, the Grantee agrees that the

Exhibit 10.4

Company shall have unilateral authority to amend the Agreement without the Grantee’s consent to the extent necessary to comply with securities or other laws applicable to issuance of shares of Stock.

Insider Trading/Market Abuse.  The Grantee acknowledges that, depending on the Grantee’s or his or her broker's country or where the shares of Stock are listed, the Grantee may be subject to insider trading restrictions and/or market abuse laws which may affect the Grantee’s ability to accept, acquire, sell or otherwise dispose of shares of Stock, rights to shares of Stock (e.g., PSUs) or rights linked to the value of shares of Stock (e.g., phantom awards, futures) during such times the Grantee is considered to have “inside information” regarding the Company as defined in the laws or regulations in the applicable jurisdictions).  Local insider trading laws and regulations may prohibit the cancellation or amendment of orders the Grantee placed before the Grantee possessed inside information.  Furthermore, the Grantee could be prohibited from (i) disclosing the inside information to any third party (other than on a “need to know” basis) and (ii) “tipping” third parties or causing them otherwise to buy or sell securities.  Keep in mind third parties includes fellow employees.  Any restrictions under these laws or regulations are separate from and in addition to any restrictions that may be imposed under any applicable insider trading policy of the Company.  The Grantee is responsible for complying with any restrictions and should speak to his or her personal advisor on this matter.

Exchange Control, Foreign Asset/Account and/or Tax Reporting.  Depending upon the country to which laws the Grantee is subject, the Grantee may have certain foreign asset/account and/or tax reporting requirements that may affect the Grantee’s ability to acquire or hold shares of Stock under the Plan or cash received from participating in the Plan (including from any dividends or dividend equivalents or sale proceeds arising from the sale of shares of Stock) in a brokerage or bank account outside the Grantee’s country of residence.  The Grantee’s country may require that the Grantee reports such accounts, assets or transactions to the applicable authorities in his or her country.  The Grantee also may be required to repatriate cash received from participating in the Plan to the Grantee’s country within a certain period of time after receipt.  The Grantee is responsible for knowledge of and compliance with any such regulations and should speak with his or her personal tax, legal and financial advisors regarding same.

Commercial Relationship.  The Grantee expressly recognizes that the Grantee’s participation in the Plan and the Company’s Award grant does not constitute an employment relationship between the Grantee and the Company. The Grantee has been granted PSUs as a consequence of the commercial relationship between the Company and the Employer, and the Employer is the Grantee’s sole employer. Based on the foregoing, (a) the Grantee expressly recognizes the Plan and the benefits the Grantee may derive from participation in the Plan do not establish any rights between the Grantee and the Affiliate that employs the Grantee, (b) the Plan and the benefits the Grantee may derive from participation in the Plan are not part of the employment conditions and/or benefits provided by the Affiliate that employs the Grantee, and (c) any modifications or amendments of the Plan by the Company or the Administrator, or a termination of the Plan by the Company, shall not constitute a change or impairment of the terms and conditions of the Grantee’s employment with the Affiliate that employs the Grantee.

Private Placement.  The grant of the Award is not intended to be a public offering of securities in the Grantee’s country of residence and/or employment but instead is intended to be a private placement. As a private placement, the Company has not submitted any registration statement, prospectus or other filings with the local securities authorities (unless otherwise required under local law), and the grant of the PSU Award is not subject to the supervision of the local securities authorities.

Exhibit 10.4

Additional Acknowledgements.  The GRANTEE also acknowledges and agrees to the following:

● The Plan is established voluntarily by the Company, it is discretionary in nature, and it may be modified, amended, suspended or terminated by the Company at any time, to the extent permitted by the Plan.

● All decisions with respect to future Awards or other grants, if any, will be at the sole discretion of the Company.

● The future value of the underlying Stock is unknown, indeterminable and cannot be predicted with certainty.

● The Award and the Stock subject to the Award, and the income and value of same, are not part of normal or expected compensation or salary for any purpose and are not intended to replace any pension rights or compensation.

● The Grantee’s participation in the Plan is voluntary.

● No claim or entitlement to compensation or damages arises from the forfeiture of the Award or any of the PSUs, the termination of the Plan, or the diminution in value of the PSUs or Stock, and the Grantee irrevocably releases the Company, its Affiliates, the Administrator and their affiliates from any such claim that may arise.

● The PSU and the Stock subject to the PSU, and the income and value of same, are not part of normal or expected compensation for purposes of, including but not limited to, calculating any severance, resignation, termination, redundancy, dismissal, end of service payments, bonuses, holiday pay, long-service awards, pension or retirement or welfare benefits or similar payments.

● Unless otherwise agreed with the Company in writing, the PSUs and the Stock subject to the PSUs, and the income and value of same, are not granted as consideration for, or in connection with, any service the Grantee may provide as a director of the Company or its Affiliates.

● Neither the Company nor its Affiliates shall be liable for any foreign exchange rate fluctuation between the Grantee’s local currency and the U.S. Dollar that may affect the value of the PSUs or of any amounts due to the Grantee pursuant to the settlement of the PSUs or the subsequent sale of any Stock acquired upon settlement.

● None of the Company, its Affiliates, nor the Administrator is providing any tax, legal or financial advice or making any recommendations regarding the Grantee’s participation in the Plan, the grant, vesting or settlement of the Grantee’s PSUs, or the Grantee’s acquisition or sale of the Stock delivered in settlement of the PSUs. The Grantee is hereby advised to consult with his own personal tax, legal and financial advisors regarding his participation in the Plan before taking any action related to the Plan.

Exhibit 10.4

SWITZERLAND

Terms and Conditions

Employee Data Privacy. The following provisions replace Section 12 of the Agreement in its entirety:

The Company, with its address at 440 E. Swedesford Road, Suite 301, Wayne, PA 19087, USA, is the controller responsible for the processing of the Grantee’s personal data by the Company and the third parties noted below, and its representative in Italy for privacy purposes is A.P.I. Applicazioni Plastiche Industriali S.p.A. with its registered address at Via Dante Alighieri n. 27, 36065 Mussolente (VI) Italy.

(a)Data Collection and Usage. Pursuant to applicable data protection laws, the Grantee is hereby notified that the Company collects, processes and uses certain personally-identifiable information about the Grantee for the legitimate interest of implementing, administering and managing the Plan and generally administering equity awards; specifically, including the Grantee’s name, home address, email address and telephone number, date of birth, social insurance number or other identification number, salary, citizenship, job title, any shares of Stock or directorships held in the Company, and details of all Performance Award Stock Units, any other entitlement to shares of Stock awarded, canceled, exercised, vested, or outstanding in the Grantee’s favor, which the Company receives from the Grantee or the Grantee’s employer (“Personal Data”). In granting the Performance Award Stock Units under the Plan, the Company will collect Personal Data for purposes of allocating shares of Stock and implementing, administering and managing the Plan. The Company’s legal basis for the collection, processing and use of Personal Data is the necessity of the processing for the Company to perform its contractual obligations under the Agreement and the Plan and the Company’s legitimate business interests of managing the Plan, administering employee equity awards and complying with its contractual and statutory obligations.

(b)Stock Plan Administration Service Provider. The Company transfers Personal Data to Merrill Lynch and its affiliates, an independent service provider based in the United States, which assists the Company with the implementation, administration and management of the Plan. In the future, the Company may select a different service provider and share Personal Data with another company that serves in a similar manner. The Company’s service provider will open an account for the Grantee to receive and trade shares of Stock. The Grantee will be asked to agree on separate terms and data processing practices with the service provider, which is a condition to the Grantee’s ability to participate in the Plan. The processing of Personal Data will take place through both electronic and non-electronic means. Personal Data will only be accessible by those individuals requiring access to it for purposes of implementing, administering and operating the Plan.

(c)International Data Transfers. The Company and its service providers are based in the United States or elsewhere throughout the world. The Grantee’s country or jurisdiction may have different data privacy laws and protections than the United States. The Company's legal basis for the transfer of the Grantee’s Personal Data to the United States is to satisfy its contractual obligations under the terms and conditions of this Agreement.

(d)Data Retention. The Company will use Personal Data only as long as is necessary to implement, administer and manage the Grantee’s participation in the Plan or as required to comply with legal or regulatory obligations, including tax and securities laws. When the Company no longer needs Personal Data, the Company will remove it from its systems. If the Company keeps Personal

Exhibit 10.4

Data longer, it would be to satisfy legal or regulatory obligations and the Company’s legal basis would be for compliance with relevant laws or regulations.

(e)Data Subject Rights. The Grantee may have a number of rights under data privacy laws in the Grantee’s country. For example, the Grantee’s rights may include the right to (i) request access or copies of Personal Data the Company processes, (ii) request rectification of incorrect Personal Data, (iii) request deletion of Personal Data, (iv) place restrictions on processing of Personal Data, (v) lodge complaints with competent authorities in the Grantee’s country, and/or (vi) request a list with the names and addresses of any potential recipients of Personal Data. To receive clarification regarding the Grantee’s rights or to exercise the Grantee’s rights, the Grantee may contact his or her local partner or human resources representative.

Notifications

Securities Law Information.  Neither this document nor any other materials relating to the grant of PSUs (a) constitutes a prospectus according to articles 35 et seq. of the Swiss Federal Act on Financial Services (“FinSA”), (b) may be publicly distributed nor otherwise made publicly available in Switzerland to any person other than an employee of the Company or (c) have been or will be filed with, approved or supervised by any Swiss reviewing body according to article 51 of FinSA or any Swiss regulatory authority, including the Swiss Financial Market Supervisory Authority (FINMA).

***

EX-10.5

Exhibit 10.5

Name:

Number of Shares of Stock subject to Stock Option:

Exercise Price Per Share:

Date of Grant:

Trinseo PLC

Amended & Restated 2014 Omnibus Incentive Plan

Non-Statutory Stock Option Agreement

This agreement (this “Agreement”) evidences an award (the “Award”) of a stock option (the “Stock Option”) granted by Trinseo PLC (the “Company”) to the undersigned (the “Optionee”) pursuant to and subject to the terms of the Trinseo PLC Amended and Restated 2014 Omnibus Incentive Plan (as amended from time to time, the “Plan”).

1.Grant of Stock Option. The Company grants to the Optionee on the date set forth above (the “Date of Grant”) a Stock Option to purchase, on the terms provided herein and in the Plan, up to the number of shares of Stock set forth above (the “Shares”) with an exercise price per Share as set forth above, in each case subject to adjustment pursuant to Section 7 of the Plan in respect of transactions occurring after the date hereof.

The Stock Option evidenced by this Agreement is a non-statutory option (that is, an option that does not qualify as an incentive stock option under Section 422 of the Code) and is granted to the Optionee in connection with the Optionee’s employment by or service to the Company and its qualifying subsidiaries. For purposes of the immediately preceding sentence, “qualifying subsidiary” means a subsidiary of the Company as to which the Company has a “controlling interest” as described in Treas. Regs. §1.409A- 1(b)(5)(iii)(E)(1).

The grant of the Stock Option is a one-time benefit and does not create any contractual or other right for the Optionee to receive a grant of stock options or benefits in lieu of stock options in the future.

2.Meaning of Certain Terms. Except as otherwise defined herein, all capitalized terms used herein have the same meaning as in the Plan.

3.Vesting; Method of Exercise; Treatment of the Stock Option Upon Termination of Employment.

(a) Vesting. As used herein with respect to the Stock Option or any portion thereof, the term “vest” means to become exercisable and the term “vested” as applied to any outstanding Stock Option (or any portion thereof) means that the Stock Option is then exercisable, subject in each case to the terms of the Plan. Unless earlier terminated, forfeited, relinquished or expired, the Stock Option shall vest as to one-third (1/3) of the Shares subject to the Stock Option on each of the first, second and third anniversaries of the Date of Grant (each, a “vesting anniversary date”

-1-

Exhibit 10.5

and the third anniversary of the Date of Grant, the “final vesting anniversary date”). The number of Shares that vest on any of the foregoing dates will be rounded down to the nearest whole Share, with the Stock Option becoming vested as to 100% of the Shares on the final vesting anniversary date. Notwithstanding the foregoing, Shares subject to the Stock Option shall not vest on any vesting anniversary date unless the Optionee has remained in continuous Employment from the Date of Grant through such vesting anniversary date.

(b) Exercise of the Stock Option. No portion of the Stock Option may be exercised until such portion vests. Each election to exercise any vested portion of the Stock Option will be subject to the terms and conditions of the Plan and shall be in writing or by electronic notice, signed (including electronic signature in form acceptable to the Administrator) by the Optionee or a transferee (if permitted by the Administrator), if any (or in such other form as is acceptable to the Administrator). Each such exercise election must be received by the Company at its principal office or by such other party as the Administrator may prescribe and be accompanied by payment in full as provided in the Plan, including, for the avoidance of doubt to the extent required by Irish law, the payment by the Optionee to the Company of an additional amount in cash equal to the aggregate par value of the shares of Stock to be delivered in respect of the portion of the Stock Option so exercised at the time of the exercise of the Stock Option. The exercise price may be paid (i) by cash or check acceptable to the Administrator, (ii) to the extent permitted by the Administrator, through a broker-assisted cashless exercise program acceptable to the Administrator, (iii) by such other means, if any, as may be acceptable to the Administrator, or (iv) by any combination of the foregoing permissible forms of payment. In the event that the Stock Option is exercised by a person other than the Optionee, the Company will be under no obligation to deliver Shares hereunder unless and until it is satisfied as to the authority of such person to exercise the Stock Option and compliance with applicable securities laws. The latest date on which the Stock Option or any portion thereof may be exercised will be the 9th anniversary of the Date of Grant (the “Final Exercise Date”); provided, however, if at such time the Optionee is prohibited by applicable law or written Company policy applicable to similarly situated employees from engaging in any open-market sales of Stock, the Final Exercise Date will be automatically extended to thirty (30) days following the date the Optionee is no longer prohibited from engaging in such open-market sales. If the Stock Option is not exercised by the Final Exercise Date, the Stock Option or any remaining portion thereof will thereupon immediately terminate.

(c) Treatment of the Stock Option Upon Termination of Employment. Except as provided in clauses (i)-(iv) below and Section 3(d) of this Agreement, if the Optionee’s Employment terminates, the Stock Option, to the extent not already vested, will be immediately forfeited upon such termination. Following termination of the Optionee’s Employment, any vested portion of the Stock Option that is then outstanding, including for the avoidance

-2-

Exhibit 10.5

of doubt any portion of the Stock Option that vests as provided in clauses (ii)-(iv) below or Section 3(d) of this Agreement, will be treated as follows:

(i)General. Subject to clauses (ii) through (v) below and Sections 3(d) and 4 of this Agreement, the Stock Option, to the extent vested immediately prior to the termination of the Optionee’s Employment, will remain exercisable until the earlier of (A) the date that is three months following the date of such termination of Employment, or (B) the Final Exercise Date, and except to the extent previously exercised as permitted by this Section 3(c)(i) will thereupon immediately terminate.

(ii)Retirement. Subject to clause (v) below and Section 4 of this Agreement, if the Optionee’s Employment terminates due to the Optionee’s Retirement (as defined below), the Stock Option, to the extent then unvested, will not terminate and will remain outstanding and eligible to vest in accordance with the provisions of Section 3(a) hereof as if the Optionee had remained in continuous Employment through each vesting anniversary date. Any portion of the Stock Option that vests in accordance with this Section 3(c)(ii), together with the portion of the Stock Option, if any, that was vested as of immediately prior to the termination of the Optionee’s Employment due to the Optionee’s Retirement, will remain exercisable until the earlier of (A) five (5) years following the date of such termination of employment and, or (B) the Final Exercise Date, and except to the extent previously exercised as permitted by this Section 3(c)(ii) will thereupon immediately terminate. For purposes hereunder, “Retirement” means a retirement from active Employment after the Optionee has attained age fifty-five (55) with at least ten (10) years of continuous service with the Company, or its predecessor entity, The Dow Chemical Company, or any of its subsidiaries, or as defined in the Optionee’s employment or other agreement with the Company.

(iii)Death; Permanent Disability. Subject to clause (v) below and Section 4 of this Agreement, if the Optionee’s Employment is terminated due to his or her death or by the Company due to his or her Permanent Disability, the Stock Option, to the extent then unvested, shall immediately vest as to all of the then unvested Shares. Any portion of the Stock Option that vests in accordance with this Section 3(c)(iii), together with the portion of the Stock Option, if any, that was vested as of immediately prior to the termination of the Optionee’s Employment due to his or her death or by the Company due to his or her Permanent Disability, will remain exercisable until the earlier of (A) the first anniversary of the Optionee’s death or the first anniversary of the date the Optionee’s Employment is terminated due to his or her Permanent

-3-

Exhibit 10.5

Disability, as applicable or (B) the Final Exercise Date, and except to the extent previously exercised as permitted by this Section 3(c)(iii) will thereupon immediately terminate.

(iv)By the Company in Connection with Restructuring or Redundancy. Subject to clause (v) below and Sections 3(d) and 4 of this Agreement, if the Optionee’s Employment is terminated by the Company other than for Cause in connection with a restructuring or redundancy, as determined by the Company, the Stock Option, to the extent then unvested, will not terminate and will remain outstanding and eligible to vest in accordance with the provisions of Section 3(a) hereof as if the Optionee had remained in continuous Employment with the Company through each vesting anniversary date. Any Stock Option that vests in accordance with this Section 3(c)(iv), together with the portion of the Stock Option, if any, that was vested as of immediately prior to the termination of the Optionee’s Employment, will remain exercisable until the earlier of (A) the later of (i) three months following the date of such termination of employment and (ii) the date that is three months following the final vesting anniversary date or (B) the Final Exercise Date, and except to the extent previously exercised as permitted by this Section 3(c)(iv) will thereupon immediately terminate.

(v)For Cause.  If the Optionee’s Employment is terminated by the Company or its subsidiaries in connection with an act or failure to act constituting Cause (as the Administrator, in its sole discretion, may determine), or such termination occurs in circumstances that in the determination of the Administrator would have entitled the Company or its subsidiaries to terminate the Optionee’s Employment for Cause, the Stock Option (whether or not vested) will immediately terminate and be forfeited upon such termination.

(d) Treatment of the Stock Option Following a Change in Control. If, within the twenty-four (24)-month period following the occurrence of a Change in Control (as defined below), (A) the Optionee’s Employment is terminated by the Company other than for Cause or, (B) if the Optionee is a current member of the Company's executive leadership team and is subject to an effective employment or other individual agreement with the Company that provides the Optionee with the ability to terminate his or her employment for “good reason”, by the Optionee for “good reason” (with such term having the meaning ascribed thereto in the employment or other individual agreement, if any, between the Optionee and the Company for so long as such agreement is in effect), upon such termination and in lieu of the treatment provided for in Section 3(c)(iv) above, the Stock Option, to the extent then outstanding and unvested, shall immediately vest as to all of the then unvested Shares. Any Stock Option that vests in accordance with this Section 3(d), together with the portion

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Exhibit 10.5

of the Stock Option, if any, that was vested as of immediately prior to the termination of the Optionee’s Employment, will remain exercisable until the earlier of (A) the date that is six months following the date of the Optionee’s termination of Employment, or (B) the Final Exercise Date, and except to the extent previously exercised as permitted by this Section 3(d) will thereupon immediately terminate.

(i)For purposes of this Agreement, “Change in Control” means the first to occur of any of the following events:

(A) an event in which any “person,” as such term is used in Sections 13(d) and 14(d) of the U.S. Securities Exchange Act of 1934, as amended (the “1934 Act”) (other than (I) the Company, (II) any subsidiary of the Company, (III) any trustee or other fiduciary holding securities under an employee benefit plan of the Company or of any subsidiary of the Company, and (IV) any company owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as their ownership of stock of the Company), is or becomes the “beneficial owner” (as defined in Section 13(d) of the 1934 Act), together with all affiliates and associates (as such terms are used in Rule 12b-2 of the General Rules and Regulations under the 1934 Act) of such person, directly or indirectly, of securities of the Company representing 40% or more of the combined voting power of the Company’s then outstanding securities;

(B) the consummation of the merger or consolidation of the Company with any other company, other than (i) a merger or consolidation which would result in the voting securities of the Company outstanding immediately prior thereto continuing to represent (either by remaining outstanding or by being converted into voting securities of the surviving entity), in combination with the ownership of any trustee or other fiduciary holding securities under an employee benefit plan of the Company or any subsidiary of the Company, more than 50% of the combined voting power of the voting securities of the Company or such surviving entity outstanding immediately after such merger or consolidation and (ii) a merger or consolidation effected to implement a recapitalization of the Company (or similar transaction) after which no “person” “beneficially owns” (with the determination of such “beneficial ownership” on the same basis as set forth in clause (A) of this definition) securities of the Company or the surviving entity of such merger or consolidation representing 50% or more of the combined voting power of the securities of the Company or the surviving entity of such merger or consolidation; or

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Exhibit 10.5

(C) the complete liquidation of the Company or the sale or disposition by the Company of all or substantially all of the Company’s assets.

4.Forfeiture; Recovery of Compensation.

(a) The Administrator may cancel, rescind, withhold or otherwise limit or restrict the Stock Option at any time if the Optionee is not in compliance with all applicable provisions of this Agreement and the Plan.

(b) By accepting the Stock Option, the Optionee expressly acknowledges and agrees that his or her rights, and those of any transferee permitted by the Administrator of the Stock Option, under the Stock Option, including to any Stock acquired under the Stock Option or proceeds from the disposition thereof, are subject to Section 6(a)(5) of the Plan (including any successor provision). Nothing in the preceding sentence shall be construed as limiting the general application of Section 8 of this Agreement.

5.Transfer of Stock Option. The Stock Option may not be transferred except as expressly permitted under Section 6(a)(3) of the Plan.

6.Responsibility for Taxes & Withholding. Regardless of any action the Company or any of its Affiliates takes with respect to any or all income tax, social insurance, payroll tax, payment on account or other tax-related items related to the Optionee’s participation in the Plan and legally applicable to the Optionee (“Tax-Related Items”), the Optionee acknowledges that the ultimate liability for all Tax-Related Items is and remains the Optionee’s responsibility and may exceed the amount actually withheld by the Company or any of its Affiliates. The Optionee further acknowledges that the Company and/or its Affiliates (a) make no representations or undertakings regarding the treatment of any Tax-Related Items in connection with any aspect to the Stock Option, including, but not limited to, the grant, vesting or exercise of the Stock Option, the transfer of Stock upon exercise of the Stock Option, the subsequent sale of Shares acquired pursuant to such transfer and the receipt of any dividends; and (b) do not commit to and are under no obligation to structure the terms of any Award to reduce or eliminate Optionee’s liability for Tax-Related Items or achieve any particular tax result. Further, if the Optionee becomes subject to tax in more than one jurisdiction between the date of grant and the date of any relevant taxable event, the Optionee acknowledges that Company and/or its Affiliates may be required to withhold or account for Tax-Related Items in more than one jurisdiction.

Prior to any relevant taxable or tax withholding event, as applicable, the Optionee will pay or make adequate arrangements satisfactory to the Company and/or its Affiliates to satisfy all Tax-Related Items. In this regard, the Optionee authorizes the Company and/or its Affiliates, or their respective agents, at their discretion, to satisfy the obligations with regard to all Tax-Related Items by one or a combination of the following:

(i)withholding from the Optionee’s wages/salary or other cash

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Exhibit 10.5

compensation paid to the Optionee by the Company and/or its Affiliates; or

(ii)withholding from proceeds of the Shares acquired upon exercise of the Stock Option either through a voluntary sale or through a mandatory sale arranged by the Company (on Optionee's behalf pursuant to this authorization); or

(iii)withholding in Shares to be transferred upon exercise of the Stock Option provided, however, that if the Optionee is a Section 16 officer of the Company under the 1934 Act, then the Company will withhold in Shares upon the relevant taxable or tax withholding event, as applicable, unless the use of such withholding method is problematic under applicable tax or securities law or has materially adverse accounting consequences, in which case, the obligation for Tax- Related Items may be satisfied by one or a combination of methods (i) and (ii) above.

To avoid negative accounting treatment, the Company and/or its Affiliates may withhold or account for Tax-Related Items by considering applicable minimum statutory withholding amounts or other applicable withholding rates. If the obligation for Tax- Related Items is satisfied by withholding in Shares, for tax purposes, the Optionee is deemed to have been transferred the full number of Shares attributable to the Stock Option at exercise, notwithstanding that a number of share are held back solely for the purpose of paying the Tax-Related Items due as a result of any aspect of the Optionee’s participation in the Plan.

The Optionee shall pay to the Company and/or its Affiliates any amount of Tax- Related Items that the Company and/or its Affiliates may be required to withhold or account for as a result of the Optionee’s participation in the Plan that will not for any reason be satisfied by the means previously described. The Company may refuse to transfer the Shares or the proceeds of the sale of Shares if the Optionee fails to comply with the Optionee’s obligations in connection with the Tax-Related Items.

By accepting this grant of Stock Option, the Optionee expressly consents to the methods of withholding Tax-Related Items by the Company and/or its Affiliates as set forth herein, including the withholding of Shares and the withholding from the Optionee’s wages/salary or other amounts payable to the Optionee. All other Tax-Related Items related to the Stock Option and any Shares transferred in satisfaction thereof are the Optionee’s sole responsibility.

7.Effect on Employment. Neither the grant of the Stock Option, nor the issuance of Shares upon exercise of the Stock Option, will give the Optionee any right to be retained in the employ or service of the Company or any of its Affiliates, affect the right of the Company or any of its Affiliates to discharge or discipline such Optionee at any time, or affect any right of such Optionee to terminate his or her Employment at any time.

8.Provisions of the Plan. This Agreement is subject in its entirety to the provisions of the Plan, which are incorporated herein by reference. A copy of the Plan as in effect on the Date of Grant has been furnished to the Optionee. By acceptance of the Stock Option, the Optionee agrees to be bound by the terms of the Plan and this Agreement. In the event of any conflict between the terms of this Agreement and the

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Exhibit 10.5

Plan, the terms of the Plan shall control.

9.Acknowledgements. The Optionee acknowledges and agrees that (i) this Agreement may be executed in two or more counterparts, each of which shall be an original and all of which together shall constitute one and the same instrument, (ii) this agreement may be executed and exchanged using facsimile, portable document format (PDF) or electronic signature, which, in each case, shall constitute an original signature for all purposes hereunder and (iii) such signature by the Company will be binding against the Company and will create a legally binding agreement when this Agreement is countersigned by the Optionee.

10.Authorization to Release and Transfer Necessary Personal Information. The Optionee hereby explicitly and unambiguously consents to the collection, use and transfer, in electronic or other form, of his or her personal data by and among, as applicable, the Company and the Affiliates for the exclusive purpose of implementing, administering and managing the Optionee’s participation in the Plan. The Optionee understands that the Company and the Affiliates may hold certain personal information about the Optionee including, but not limited to, the Optionee’s name, home address and telephone number, date of birth, social security number (or any other social or national identification number), salary, nationality, job title, number of Stock Options and/or Shares held and the details of all Stock Options or any other entitlement to Shares awarded, cancelled, vested, unvested or outstanding for the purpose of implementing, administering and managing the Optionee’s participation in the Plan (the “Data”). The Optionee understands that the Data may be transferred to the Company or any of the Affiliates, or to any third parties assisting in the implementation, administration and management of the Plan, that these recipients may be located in the Optionee’s country or elsewhere, and that any recipient’s country (e.g., the United States) may have different data privacy laws and protections than the Optionee’s country. The Optionee understands that he or she may request a list with the names and addresses of any potential recipients of the Data by contacting his or her local human resources representative. The Optionee authorizes the recipients to receive, possess, use, retain and transfer the Data, in electronic or other form, for the sole purpose of implementing, administering and managing his or her participation in the Plan, including any requisite transfer of such Data to a broker or other third party assisting with the administration of the Stock Option under the Plan or with whom Stock acquired pursuant to the exercise of the Stock Option or cash from the sale of such Stock may be deposited. Furthermore, the Optionee acknowledges and understands that the transfer of the Data to the Company or the Affiliates or to any third parties is necessary for his or her participation in the Plan. The Optionee understands that Data will be held only as long as is necessary to implement, administer and manage his or her participation in the Plan. The Optionee understands that he or she may, at any time, view the Data, request additional information about the storage and processing of the Data, require any necessary amendments to the Data or refuse or withdraw the consents herein by contacting his or her local human resources representative in writing. The Optionee further acknowledges that withdrawal of consent may affect his or her ability to vest in, exercise or realize benefits from the Stock Option, and his or her ability to participate in the Plan. For more information on the consequences of refusal to consent or withdrawal of consent, the Optionee understands that he or she may contact his or her local human resources representative.

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Exhibit 10.5

Finally, upon request of the Company or the Optionee’s employer (the “Employer”), the Optionee agrees to provide an executed data privacy consent form (or any other agreements or consents that may be required by the Company and/or the Employer) that the Company and/or the Employer may deem necessary to obtain from the Optionee for the purpose of administering the Optionee’s participation in the Plan in compliance with the data privacy laws in the Optionee’s country, either now or in the future. The Optionee understands and agrees that the Optionee will not be able to participate in the Plan if the Optionee fails to provide any such consent or agreement requested by the Company and/or the Employer.

11.Electronic Delivery and Execution. The Optionee hereby consents and agrees to electronic delivery of any documents that the Company may elect to deliver (including, but not limited to, plan documents, prospectus and prospectus supplements, grant or award notifications and agreements, account statements, annual and quarterly reports, and all other forms of communications) in connection with this and any other Award made or offered under the Plan. The Optionee understands that, unless revoked by the Optionee by giving written notice to the Company pursuant to the Plan, this consent will be effective for the duration of the Agreement. The Optionee also understands that he or she will have the right at any time to request that the Company deliver written copies of any and all materials referred to above. The Optionee hereby consents to any and all procedures the Company has established or may establish for an electronic signature system for delivery and acceptance of any such documents that the Company may elect to deliver, and agree that his or her electronic signature is the same as, and will have the same force and effect as, his or her manual signature. The Optionee consents and agrees that any such procedures and delivery may be affected by a third party engaged by the Company to provide administrative services related to the Plan.

12.Appendix. Notwithstanding any provision of the Agreement to the contrary, this Stock Option grant and the Shares acquired under the Plan shall be subject to any and all special terms and provisions as set forth in the Appendix, if any, for the Optionee’s country of residence (and country of employment, if different). Moreover, if the Optionee relocates to one of the countries included in the Appendix, the additional terms and conditions for such country will apply to the Optionee, to the extent the Company determines that the application of such terms and conditions is necessary or advisable for legal or administrative reasons.  The Appendix constitutes part of the Agreement.

13.Severability. The provisions of this Agreement are severable and if any one or more provisions are determined to be illegal or otherwise unenforceable, in whole or in part, the remaining provisions shall nevertheless be binding and enforceable.

[Signature page follows]

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Exhibit 10.5

IN WITNESS WHEREOF, the Company has caused this Agreement to be executed by its duly authorized officer.

TRINSEO PLC

By:

Name:

Title:

Dated:

Acknowledged and Agreed:

By:

Signature Page to Non-Statutory Stock Option Agreement

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Exhibit 10.5

COUNTRY APPENDIX

ADDITIONAL TERMS AND CONDITIONS TO NON-STATUTORY STOCK OPTION AGREEMENT

This Country Appendix (“Appendix”) includes the following additional terms and conditions that govern the Optionee’s Stock Option for all Optionees that reside and/or work outside of the United States.

Notifications

This Appendix also includes information regarding exchange controls and certain other issues of which the Optionee should be aware with respect to the Optionee’s participation in the Plan. The information is based on the securities, exchange control and other laws in effect in the respective countries as of January 2022. Such laws are often complex and change frequently. As a result, the Company strongly recommends that the Optionee does not rely on the information in this Appendix as the only source of information relating to the consequences of the Optionee’s participation in the Plan, because the information may be out of date at the time that the Stock Option or portions thereof vest, or Shares are transferred upon exercise of the Stock Option, or the Optionee sells any Shares acquired under the Plan.

In addition, the information contained herein is general in nature and may not apply to the Optionee’s particular situation, and none of the Company, its Affiliates, nor the Administrator is in a position to assure the Optionee of a particular result. Accordingly, the Optionee is advised to seek appropriate professional advice as to how the relevant laws in the Optionee’s country of residence and/or work may apply to the Optionee’s situation.

Finally, if the Optionee transfers employment after the Grant Date, or is considered a resident of another country for local law purposes following the Grant Date, the notifications contained herein may not be applicable to the Optionee, and the Administrator shall, in its discretion, determine to what extent the terms and conditions contained herein shall be applicable to the Optionee.

Terms and Conditions Applicable to All Non-U.S. Jurisdictions

English Language. The Optionee acknowledges and agrees that it is the Optionee’s express intent that this Agreement, the Plan and all other documents, rules, procedures, forms, notices and legal proceedings entered into, given or instituted pursuant to the Stock Option, be drawn up in English. If the Optionee has received this Agreement, the Plan or any other rules, procedures, forms or documents related to the Stock Option translated into a language other than English, and if the meaning of the translated version is different than the English version, the English version will control.

Compliance with Law.  Notwithstanding any other provision of the Plan or this Agreement, unless there is an exemption from any registration, qualification or other legal requirement applicable to the Shares, the Company shall not be required to deliver any shares issuable upon exercise of the Stock Option prior to the completion of any registration or qualification of the shares under any local, state, federal or foreign securities or exchange control law or under rulings or regulations of the U.S. Securities and Exchange Commission (“SEC”) or of any other

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Exhibit 10.5

governmental regulatory body, or prior to obtaining any approval or other clearance from any local, state, federal or foreign governmental agency, which registration, qualification or approval the Company shall, in its absolute discretion, deem necessary or advisable. The Optionee understands that the Company is under no obligation to register or qualify the shares with the SEC or any state or foreign securities commission or to seek approval or clearance from any governmental authority for the issuance or sale of the shares.  Further, the Optionee agrees that the Company shall have unilateral authority to amend the Agreement without the Optionee’s consent to the extent necessary to comply with securities or other laws applicable to issuance of Shares.

Insider Trading/Market Abuse.  The Optionee acknowledges that, depending on the Optionee’s or his or her broker's country or where the Shares are listed, the Optionee may be subject to insider trading restrictions and/or market abuse laws which may affect the Optionee’s ability to accept, acquire, sell or otherwise dispose of Shares, rights to Shares (e.g., Stock Options) or rights linked to the value of Shares (e.g., phantom awards, futures) during such times the Optionee is considered to have “inside information” regarding the Company as defined in the laws or regulations in the applicable jurisdictions).  Local insider trading laws and regulations may prohibit the cancellation or amendment of orders the Optionee placed before the Optionee possessed inside information.  Furthermore, the Optionee could be prohibited from (i) disclosing the inside information to any third party (other than on a “need to know” basis) and (ii) “tipping” third parties or causing them otherwise to buy or sell securities.  Keep in mind third parties includes fellow employees.  Any restrictions under these laws or regulations are separate from and in addition to any restrictions that may be imposed under any applicable insider trading policy of the Company.  The Optionee is responsible for complying with any restrictions and should speak to his or her personal advisor on this matter.

Exchange Control, Foreign Asset/Account and/or Tax Reporting.  Depending upon the country to which laws the Optionee is subject, the Optionee may have certain foreign asset/account and/or tax reporting requirements that may affect the Optionee’s ability to acquire or hold Shares under the Plan or cash received from participating in the Plan (including from any dividends or dividend equivalents or sale proceeds arising from the sale of Shares) in a brokerage or bank account outside the Optionee’s country of residence.  The Optionee’s country may require that the Optionee reports such accounts, assets or transactions to the applicable authorities in his or her country.  The Optionee also may be required to repatriate cash received from participating in the Plan to the Optionee’s country within a certain period of time after receipt.  The Optionee is responsible for knowledge of and compliance with any such regulations and should speak with his or her personal tax, legal and financial advisors regarding same.

Commercial Relationship. The Optionee expressly recognizes that the Optionee’s participation in the Plan and the Company’s Stock Option grant does not constitute an employment relationship between the Optionee and the Company. The Optionee has been granted a Stock Option as a consequence of the commercial relationship between the Company and the Employer, and the Employer is the Optionee’s sole employer. Based on the foregoing, (a) the Optionee expressly recognizes the Plan and the benefits the Optionee may derive from participation in the Plan do not establish any rights between the Optionee and the Affiliate that employs the Optionee, (b) the Plan and the benefits the Optionee may derive from participation in the Plan are not part of the employment conditions and/or benefits provided by the Affiliate that employs the Optionee, and (c) any modifications or amendments of the Plan by the Company

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Exhibit 10.5

or the Administrator, or a termination of the Plan by the Company, shall not constitute a change or impairment of the terms and conditions of the Optionee’s employment with the Affiliate that employs the Optionee.

Private Placement. The grant of the Stock Option is not intended to be a public offering of securities in the Optionee’s country of residence and/or employment but instead is intended to be a private placement. As a private placement, the Company has not submitted any registration statement, prospectus or other filings with the local securities authorities (unless otherwise required under local law), and the grant of the Stock Option is not subject to the supervision of the local securities authorities.

Additional Acknowledgements. The OPTIONEE also acknowledges and agrees to the following:

● The Plan is established voluntarily by the Company, it is discretionary in nature, and it may be modified, amended, suspended, or terminated by the Company at any time, to the extent permitted by the Plan.

● All decisions with respect to future Awards or other grants, if any, will be at the sole discretion of the Company.

●The future value of the underlying Share is unknown, undeterminable and cannot be predicted with certainty.

●If the underlying Share does not increase in value after the Date of Grant, the Stock Option will have no value.

●If the Optionee exercises the Stock Option and acquire Shares, the value of such Shares may increase or decrease in value, even below the exercise price.

● The Award and the Shares subject to the Award, and the income and value of same, are not part of normal or expected compensation or salary for any purpose and are not intended to replace any pension rights or compensation.

●The Optionee's participation in the Plan is voluntary.

● No claim or entitlement to compensation or damages arises from the forfeiture of the Award on the Stock Option, the termination of the Plan, or the diminution in value of the Stock Option or Shares, and the Optionee irrevocably releases the Company, its Affiliates, the Administrator and their affiliates from any such claim that may arise.

● The Stock Option and the Share subject to the Stock Option, and the income and value of same, are not part of normal or expected compensation for purposes of, including but not limited to, calculating any severance, resignation, termination, redundancy, dismissal, end-of-service payments, bonuses, holiday pay, long-service awards, pension or retirement or welfare benefits or similar payments.

● Unless otherwise agreed with the Company in writing, the Award and the Shares subject to the Stock Option, and the income and value of same, are not granted as consideration

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Exhibit 10.5

for, or in connection with, any service the Optionee may provide as a director of the Company or its Affiliates.

● Neither the Company nor its Affiliates shall be liable for any foreign exchange rate fluctuation between the Optionee's local currency and the U.S. Dollar that may affect the value of the Stock Option or Shares or of any amounts due to the Optionee pursuant to the settlement of the Stock Option or the subsequent sale of Shares acquired upon settlement.

● None of the Company, its Affiliates, nor the Administrator is providing any tax, legal or financial advice or making any recommendations regarding the Optionee’s participation in the Plan, the grant, vesting or settlement of the Optionee’s Stock Option, or the Optionee’s acquisition or sale of the Shares transferred upon exercise of the Stock Option. The Optionee is hereby advised to consult with his own personal tax, legal and financial advisors regarding his participation in the Plan before taking any action related to the Plan.

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Exhibit 10.5

EUROPEAN UNION (“EU”) / EUROPEAN ECONOMIC AREA (“EEA”) / SWITZERLAND / UNITED KINGDOM

Terms and Conditions

Employee Data Privacy. If the Optionee resides and/or works in the EU/EEA, Switzerland or the United Kingdom, the following provisions replace Section 10 of the Agreement in its entirety:

The Company, with its address at 440 E. Swedesford Road, Suite 301, Wayne, PA 19087, USA, is the controller responsible for the processing of the Optionee’s personal data by the Company and the third parties noted below, and itsrepresentativeinItalyforprivacypurposes is A.P.I. Applicazioni Plastiche Industriali S.p.A. with its registered address at Via Dante Alighieri n. 27, 36065 Mussolente (VI)Italy.

(a)Data Collection and Usage. Pursuant to applicable data protection laws, the Optionee is hereby notified that the Company collects, processes and uses certain personally-identifiable information about the Optionee for the legitimate interest of implementing, administering and managing the Plan and generally administering equity awards; specifically, including the Optionee’s name, home address, email address and telephone number, date of birth, social insurance number or other identification number, salary, citizenship, job title, any Shares or directorships held in the Company, and details of all Stock Options, any other entitlement to Shares awarded, canceled, exercised, vested, or outstanding in the Optionee’s favor, which the Company receives from the Optionee or the Optionee’s employer (“Personal Data”). In granting the Stock Options under the Plan, the Company will collect Personal Data for purposes of allocating Shares and implementing, administering and managing the Plan. The Company’s legal basis for the collection, processing and use of Personal Data is the necessity of the processing for the Company to perform its contractual obligations under the Agreement and the Plan and the Company’s legitimate business interests of managing the Plan, administering employee equity awards and complying with its contractual and statutory obligations.

(b)Stock Plan Administration Service Provider. The Company transfers Personal Data to Merrill Lynch and its affiliates, an independent service provider based in the United States, which assists the Company with the implementation, administration and management of the Plan. In the future, the Company may select a different service provider and share Personal Data with another company that serves in a similar manner. The Company’s service provider will open an account for the Optionee to receive and trade Shares. The Optionee will be asked to agree on separate terms and data processing practices with the service provider, which is a condition to the Optionee’s ability to participate in the Plan. The processing of Personal Data will take place through both electronic and non-electronic means. Personal Data will only be accessible by those individuals requiring access to it for purposes of implementing, administering and operating the Plan.

(c)International Data Transfers. The Company and its service providers are based in the United States or elsewhere throughout the world. The Optionee’s country or jurisdiction may have different data privacy laws and protections than the United States. The Company's legal basis for the transfer of the Optionee’s Personal Data to the United States is to satisfy its contractual obligations under the terms and conditions of this Agreement.

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Exhibit 10.5

(d)Data Retention. The Company will use Personal Data only as long as is necessary to implement, administer and manage the Optionee’s participation in the Plan or as required to comply with legal or regulatory obligations, including tax and securities laws. When the Company no longer needs Personal Data, the Company will remove it from its systems. If the Company keeps Personal Data longer, it would be to satisfy legal or regulatory obligations and the Company’s legal basis would be for compliance with relevant laws or regulations.

(e)Data Subject Rights. The Optionee may have a number of rights under data privacy laws in the Optionee’s country. For example, the Optionee’s rights may include the right to (i) request access or copies of Personal Data the Company processes, (ii) request rectification of incorrect Personal Data, (iii) request deletion of Personal Data, (iv) place restrictions on processing of Personal Data, (v) lodge complaints with competent authorities in the Optionee’s country, and/or (vi) request a list with the names and addresses of any potential recipients of Personal Data. To receive clarification regarding the Optionee’s rights or to exercise the Optionee’s rights, the Optionee may contact his or her local partner or human resources representative.

BELGIUM

Terms and Conditions

Timing of Acceptance. The Optionee agrees that he or she will not accept the Option until a date that is on or after the 61st day on which it is offered to the Optionee. The date of offer is the date on which the Company communicates the material terms (i.e., the exercise price and number of Shares subject to the Stock Option) to the Optionee. Any acceptance inadvertently given by the Optionee before the 61st day following the offer date shall be considered effective as of the 61st day following the offer date.

Notifications

Foreign Asset / Account Reporting Information. If Optionee is a Belgian resident, Optionee is required to report any taxable income attributable to the grant of the Stock Option on his or her annual tax return. In addition, the Optionee is required to report any securities (e.g., Shares) or bank accounts opened and maintained outside Belgium on his or her annual tax return. In a separate report, certain details regarding such foreign accounts (including the account number, bank name and country in which such account was opened) must be provided to the Central Contact Point of the National Bank of Belgium. The form, as well as additional information on how to complete it, can be found on the website of the National Bank of Belgium (www.nbb.be) under the caption Kredietcentrales / Centrales des crédits.

Stock Exchange Tax.  A stock exchange tax applies to transactions executed by a Belgian resident through a financial intermediary, such as a bank or broker.  If the transaction is conducted through a Belgian financial intermediary, it may withhold the stock exchange tax, but if the transaction is conducted through a non-Belgian financial intermediary, the Belgian resident may need to report and pay the stock exchange tax directly.  The stock exchange tax likely will apply when Shares acquired under the Plan are sold.  Belgian residents should consult with a personal tax or financial advisor for additional details on their obligations with respect to the stock exchange tax.

Annual Securities Account Tax Information.  An annual securities accounts tax may be payable if the total value of securities held in a Belgian or foreign securities account (e.g., Shares acquired

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Exhibit 10.5

under the Plan) exceeds a certain threshold on four reference dates within the relevant reporting period (i.e., December 31, March 31, June 30 and September 30).  In such case, the tax will be due on the value of the qualifying securities held in such account.  The Optionee should consult with his or her personal tax advisor regarding the application of this tax.

DENMARK

Terms and Conditions

Stock Option Act.  Notwithstanding any provisions in the Agreement to the contrary, if the Optionee is determined to be an "Employee," as defined in section 2 of the Danish Act on the Use of Rights to Purchase or Subscribe for Shares, etc. in Employment Relationships (the "Stock Option Act"), the treatment of the Award upon termination of employment shall be governed by the Stock Option Act.  However, if the provisions in the Agreement or the Plan governing the treatment of the Award upon a termination are more favorable, the provisions of the Agreement or the Plan will govern.

FRANCE

Terms and Conditions

Use of English Language. Les parties reconnaissent avoir exigé la rédaction en anglais de la présente convention, ainsi que de tous documents exécutés, avis donnés et procédures judiciaires intentées, directement ou indirectement, relativement à ou suite à la présente convention.

Notifications

Award Not French Qualified. The Optionee understands and acknowledges that the Stock Option granted under this Agreement are not intended to qualify for specific tax and social security treatment pursuant to Sections L. 225-177 to L. 225-186-1 and Sections L. 22-10-56 to L. 22-10-58 of the French Commercial Code, as amended.

Exchange Control Information. Grantee must declare to the customs and excise authorities any cash or securities he or she imports or exports without the use of a financial institution when the value of the cash or securities is equal to or exceeds €10,000.

Foreign Account / Assets Reporting Information. If the Grantee is a French resident and retains Stock acquired under the Plan outside of France or maintains a foreign bank account, the Grantee is required to report such to the French tax authorities when filing the Grantee's annual tax return. Failure to comply could trigger significant penalties.

GERMANY

Notifications

Exchange Control Information. Cross-border payments in excess of €12,500 must be reported monthly to the German Federal Bank. If the Optionee uses a German bank to transfer a cross-border payment in excess of €12,500 in connection with the sale of the Shares acquired under the Plan, the bank will make the report for the Optionee. Optionee is responsible for satisfying any applicable reporting obligation.

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Exhibit 10.5

HONG KONG

Terms and Conditions

Exercise of Stock Option. In the event that the Stock Option is settled within six (6) months of the Grant Date, the Optionee agrees that the Optionee (or his / her beneficiary) will not sell or otherwise dispose of any such Shares prior to the six (6)-month anniversary of the Grant Date.

Wages. The Stock Option and Shares underlying the Stock Option do not form part of the Optionee's wages for the purposes of calculating any statutory or contractual payments under Hong Kong law. The Company specifically intends that the Plan will not be an occupational retirement scheme for purposes of the Occupational Retirement Schemes Ordinance.

Notifications

Securities Law Information. Warning: The Stock Option and any Shares transferred pursuant to the exercise of the Stock Option do not constitute a public offering of securities under Hong Kong law and are available only to employees of the Company and its Affiliates. The Agreement, the Plan, and any rules, procedures, forms or other incidental communication materials have not been prepared in accordance with and are not intended to constitute a “prospectus” for a public offering of securities under the applicable securities legislation in Hong Kong, nor have the documents been reviewed by any regulatory authority in Hong Kong. The Stock Option and any related documentation are intended only for the personal use of each eligible employee of the Company or its Affiliates and may not be distributed to any other person. If the Optionee is in any doubt about any of the contents of the Agreement, the Plan, or any rules, procedures or forms, the Optionee should obtain independent professional advice.

IRELAND

Notifications

Director Notification Obligation.  Directors, shadow directors and secretaries of an Irish Subsidiary or other affiliate of the Company whose interest in the Company represents more than 1% of the Company’s voting share capital must notify the Irish Subsidiary or other affiliate of the Company in writing when acquiring or disposing of their interest in the Company (e.g., Stock Options, Shares, etc.), when becoming aware of the event giving rise to the notification requirement, or when becoming a director or secretary if such an interest exist at the time.  This notification requirement also applies to any rights or shares acquired by the director’s spouse or children under the age of 18 (whose interests will be attributed to the director, shadow director or secretary).

ITALY

Terms and Conditions

Plan Document Acknowledgment. The Optionee further acknowledges that he or she has read and specifically and expressly approves the Data Privacy section above as well as the following sections of the Agreement Section 1 (“Grant of Stock Options”); Section 3 (“Vesting; Method

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Exhibit 10.5

of Exercise; Treatment of the Stock Option Upon Termination of Employment”); Section 4 (“Forfeiture; Recovery of Compensation”); Section 5 (“Transfer of Stock Option”); Section 6 (“Responsibility for Taxes & Withholding”); Section 11 (“Imposition of Other Requirements”); Country Appendix (“English Language”; “Additional Acknowledgements”).

Notifications

Foreign Asset / Account Reporting Information. The Optionee understands that if the Optionee is an Italian resident and at any time during the fiscal year the Optionee holds foreign financial assets (including cash and Shares) which may generate income taxable in Italy, the Optionee is required to report these assets on the Optionee’s annual tax return (UNICO Form, RW Schedule) for the year during which the assets are held, or on a special form if no tax return is due.  These reporting obligations will also apply to Italian residents who are the beneficial owners of foreign financial assets, even if the Optionee does not directly hold investments abroad or foreign assets.

Tax on Foreign Financial Assets. Individuals resident in Italy are subject to a tax on the value of financial assets held outside of Italy. The taxable amount will be the fair market value of the financial assets (including Shares) on December 31 or on the last day the Shares were held (the tax is levied in proportion to the number of days the shares were held during the calendar year). The tax is assessed as part of the annual tax return.

MEXICO

Terms and Conditions

Plan Document Acknowledgement

By accepting the Stock Option, the Optionee acknowledges that he or she has received a copy of the Plan and the Agreement, including this Appendix, which the Optionee has reviewed. The Optionee acknowledges further that he or she accepts all the provisions of the Plan and the Agreement, including this Appendix. The Optionee also acknowledges that he or she has read and specifically and expressly approves the terms and conditions set forth in “Additional Acknowledgements” in this Appendix, which clearly provides as follows:

(1)The Optionee’s participation in the Plan does not constitute an acquired right;

(2)The Plan and the Optionee’s participation in it are offered by the Company on a wholly discretionary basis;

(3)The Optionee’s participation in the Plan is voluntary; and

(4)Neither the Company nor any Affiliate is responsible for any decrease in the value of the Stock Option and/or Stock acquired under the Plan.

Labor Law Policy and Acknowledgment

By accepting the Options, the Optionee expressly recognizes that the Company, with registered offices at Riverside One, Sir John Rogerson’s Quay, Dublin 2, Dublin, Ireland D02 X576, is solely responsible for the administration of the Plan and that the Optionee’s participation in the Plan and acquisition of Stock do not constitute an employment relationship between the Optionee and the

-19-

Exhibit 10.5

Company since the Optionee is participating in the Plan on a wholly commercial basis and his or her sole employer is Trinseo de Mexico, S. de R.L. de C.V., Trinseo Services de Mexico, S. de R.L. de C.V., or Altuglas Mexico S.A. de C.V. (together, “Trinseo Mexico”). Based on the foregoing, the Optionee expressly recognizes that the Plan and the benefits that he or she may derive from participating in the Plan do not establish any rights between the Optionee and the employer, Trinseo Mexico, and do not form part of the employment conditions and/or benefits provided by Trinseo Mexico, and any modification of the Plan or its termination shall not constitute a change or impairment of the terms and conditions of the Optionee’s employment.

The Optionee further understands that his or her participation in the Plan is as a result of a unilateral and discretionary decision of the Company; therefore, the Company reserves the absolute right to amend and/or discontinue the Optionee’s participation at any time without any liability to the Optionee.

Finally, the Optionee hereby declares that he or she does not reserve to him- or herself any action or right to bring any claim against the Company for any compensation or damages regarding any provision of the Plan or the benefits derived under the Plan, and the Optionee therefore grants a full and broad release to the Company, and its subsidiaries, branches, representative offices, shareholders, directors, officers, employees, agents, or legal representatives with respect to any claim that may arise.

Spanish Translation

Reconocimiento del Documento del Plan

Al aceptar las Opción Sobre Acciones (Opción), el Beneficiario reconoce que ha recibido una copia del Plan y el Acuerdo, con inclusión de este Anexo, que el Beneficiario ha revisado. El Beneficiario reconoce, además, que acepta todas las disposiciones del Plan y en el Acuerdo, incluyendo este Anexo. El Beneficiario también reconoce que ha leído y que concretamente aprueba de forma expresa los términos y condiciones establecidos en la Sección “Reconocimientos Adicionales” de este Anexo, que claramente dispone lo siguiente:

(1)La participación del Beneficiario en el Plan no constituye un derecho adquirido;

(2)El Plan y la participación del Beneficiario en el Plan se ofrecen por la Compañía en su discrecionalidad total;

(3)Que la participación del Beneficiario en el Plan es voluntaria; y

(4)Ni la Compañía ni sus Afiliadas son responsables por la reducción del valor de la Opción de Compra de Acciones emitida bajo el Plan.

Política Laboral y Reconocimiento

Al aceptar las Options, el Beneficiario expresamente reconoce que la Compañía, con sus oficinas registradas y ubicadas en Riverside One, Sir John Rogerson’s Quay, Dublin 2, Dublin, Ireland D02 X576, es la única responsable por la administración del Plan y que la participación del Beneficiario en el Plan y en su caso la adquisición de Acciones no constituyen una relación de trabajo entre el Beneficiario y la Compañía, ya que el Beneficiario participa en el Plan en un marco totalmente comercial y su único patrón es Trinseo de Mexico, S. de R.L. de C.V., Trinseo Services

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Exhibit 10.5

de Mexico, S. de R.L. de C.V., o Altuglas Mexico S.A. de C.V. (juntos, “Trinseo Mexico”). Derivado de lo anterior, el Beneficiario expresamente reconoce que el Plan y los beneficios que pudieran derivar de la participación en el Plan no establecen derecho alguno entre el Beneficiario y el patrón, Trinseo Mexico, y no forma parte de las condiciones de trabajo y/o las prestaciones otorgadas por Trinseo Mexico, y que cualquier modificación al Plan o su terminación no constituye un cambio o desmejora de los términos y condiciones de la relación de trabajo del Beneficiario.

Asimismo, el Beneficiario reconoce que su participación en el Plan se ha resultado de una decisión unilateral y discrecional de la Compañía; por lo tanto, la Compañía se reserva el derecho absoluto de modificar y/o terminar la participación del Beneficiario en cualquier momento y sin responsabilidad alguna frente el Beneficiario.

Finalmente, el Beneficiario por este medio declara que no se reserva ninguna derecho o acción en contra de la Compañía por cualquier compensación o daños y perjuicios en relación de las disposiciones del Plan o de los beneficios derivados del Plan, y por lo tanto, el Beneficiario otorga el más amplio finiquito que en derecho proceda a la Compañía, y sus filiales, oficinas de representación, accionistas, directores, autoridades, empleados, agentes, o representantes legales en relación con cualquier demanda que pudiera surgir.

Notifications

Securities Law Notification.

The Options granted, and any Stock acquired, under the Plan have not been registered with the National Register of Securities maintained by the Mexican National Banking and Securities Commission and cannot be offered or sold publicly in Mexico. In addition, the Plan, the Agreement and any other document relating to the Options may not be publicly distributed in Mexico. These materials are addressed to the Optionee because of the Optionee’s existing relationship with the Company and any Affiliate, and these materials should not be reproduced or copied in any form. The offer contained in these materials does not constitute a public offering of securities but rather constitutes a private placement of securities addressed specifically to individuals who are present employees of Trinseo Mexico made in accordance with the provisions of the Mexican Securities Market Law, and any rights under such offering shall not be assigned or transferred.

NETHERLANDS

Terms and Conditions

Waiver of Termination Rights.  In consideration of the grant of the Stock Option, the Optionee agrees that he or she waives any and all rights to compensation or damages as a result of any termination of employment for any reason whatsoever, insofar as those rights result or may result from (a) the loss or diminution in value of such rights or entitlements under the Plan, or (b) the Optionee ceases to have rights under, or ceasing to be entitled to any awards under the Plan as a result of such termination.

SWITZERLAND

Notifications

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Exhibit 10.5

Securities Law Information. Neither this document nor any other materials relating to the grant of Stock Options (i) constitutes a prospectus according to articles 35 et seq. of the Swiss Federal Act on Financial Services (“FinSA”) (ii) may be publicly distributed nor otherwise made publicly available in Switzerland to any person other than an employee of the Company or (iii) have been or will be filed with, approved or supervised by any Swiss reviewing body according to article 51 of FinSA or any Swiss regulatory authority, including the Swiss Financial Market Supervisory Authority (FINMA).

UNITED KINGDOM

Terms and Conditions

Tax Withholding and National Insurance Contributions Acknowledgement. Notwithstanding any provisions in the Agreement, the Optionee agrees that he or she is liable for all Tax-Related Items and hereby covenants to pay all such Tax-Related Items, as and when requested by the Company, the Employer, or by Her Majesty’s Revenue and Customs (“HMRC”) or any other tax authority or other relevant authority. The Optionee also agrees to indemnify and keep indemnified the Company and the Employer against any Tax-Related Items that they are required to pay or withhold, or have paid or will pay, to HMRC (or any other tax authority or other relevant authority) on the Optionee’s behalf.

Notwithstanding the foregoing, if the Optionee is a director or executive officer of the Company (within the meaning of Section 13(k) of the U.S. Securities Exchange Act of 1934, as amended), the terms of the immediately foregoing provision may not apply to the Optionee if the indemnification is viewed as a loan. In this case, if the amount of any income tax due is not collected from or paid by the Optionee within ninety (90) days of the end of the U.K. tax year in which an event giving rise to the indemnification described above occurs, the amount of any uncollected income tax may constitute an additional benefit to the Optionee on which additional income tax and national insurance contributions (“NICs”) may be payable. The Optionee will be responsible for reporting and paying any income tax due on this additional benefit directly to HMRC under the self-assessment regime and for paying to the Company or the Employer, as applicable, any employee NICs due on this additional benefit, which the Company or the Employer may recover from the Optionee by any of the means referred to in Section 6 of the Agreement.

Exclusion of Claim. The Optionee acknowledges and agrees that the Optionee will have no entitlement to compensation or damages insofar as such entitlement arises or may arise from the Optionee’s ceasing to have rights under or to be entitled to the Stock Options, whether or not as a result of termination of Optionee’s Employment (whether the termination is in breach of contract or otherwise), or from the loss or diminution in value of the Stock Options. Upon the grant of the Stock Options, the Optionee shall be deemed to have waived irrevocably any such entitlement.

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EX-10.6

Exhibit 10.6

Name:

Number of Cash Units Awarded:

Date of Grant:

Trinseo PLC

Amended & Restated 2014 Omnibus Incentive Plan

Cash Unit Agreement

Thisagreement(this“Agreement”)evidencesanaward(the“Award”)ofcashunits(the“Cash Units”)grantedbyTrinseoPLC(the“Company”)tothe undersigned(the“Grantee”)pursuanttotheTrinseo PLC Amended and Restated 2014OmnibusIncentivePlan(as amended from time to time, the “Plan”), which is incorporated herein byreference.

1.Grant of Cash Units. On the date of grant set forth above (the “Grant Date”) the Company granted to the Grantee an award consisting of the right to receive, on the terms provided herein and in the Plan, an amount equal to the Fair Market Value of one share of Stock with respect to each Cash Unit forming part of the Award, in each case, subject to adjustment pursuant to Section 7 of the Plan in respect of transactions occurring after the datehereof.

The grant of the Cash Units is a one-time benefit and does not create any contractual or other right for the Grantee to receive a grant of cash units or benefits in lieu of cash units in the future.

The Award shall not be interpreted to bestow upon the Grantee any equity interest or ownership in the Company or any Affiliate, and the Grantee shall not have any rights of a shareholder of Stock, and shall not be entitled to receive or be credited with any dividends declared and payable on any share of Stock.

2.Meaning of Certain Terms. Except as otherwise defined herein, all capitalized terms used herein have the same meaning as in thePlan.

3.Vesting, etc.

(a) TheAwardshallvestinthree equal installments on the first, second and third anniversary of the Grant Date (each such date, a “Vesting Date”), subjecttotheGrantee’scontinuedEmploymentwiththeCompanythrough each applicable Vesting Date.

(b) Exceptasprovidedinsections(c)and(d)below,iftheGrantee’s Employment with the Company terminates for any reason prior to any Vesting Date, the unvested portion of the Award will be automatically and immediately forfeited upon suchtermination.

(c) If the Grantee’s Employment terminates due to his or her Retirement (as defined below), death, Permanent Disability, or due to a restructuring or

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Exhibit 10.6

redundancy, in each case, prior to any Vesting Date, the Award, to the extent then outstanding, will be treated as follows:

i. IftheGrantee’sEmploymentterminatesasaresultoftheGrantee’s Retirement (as defined below), following such termination the Award will continue to vest as if the Grantee had remainedincontinuousEmploymentthroughthe Vesting Date. For purposes hereunder, “Retirement” means a retirement from active Employment after the Grantee has attained age 55 with at least 10 years of continuous service with the Company, or its predecessor entity, The Dow Chemical Company, oranyofitssubsidiaries,orasdefinedintheGrantee'semployment or other agreement with theCompany.

ii.IftheGrantee’sEmploymentisterminatedduetohisorherdeathor by the Company due to his or her Permanent Disability, upon such termination, the Award will immediately vest in an amount equal to (A) the total number of unvested Cash Units, multiplied by (B) a fraction, the numerator of which is the number of full months occurring between (i) the later of the Grant Date or the most recent Vesting Date and (ii) the Grantee’s date of death of Permanent Disability, and the denominator of which is the number of months between (x) the later of the Grant Date or the most recent Vesting Date and (y) and the final Vesting Date.

iii.If the Grantee’s Employment is terminated by the Company other than for Cause in connection with a restructuring or redundancy, as determinedbytheCompany,uponsuchtermination,theAwardwill vest on the next Vesting Date in an amount equal to (A) the total number of unvested Cash Units multiplied by (B) a fraction, the numerator of which is number of full months occurring between (i) the later of the Grant Date or the most recent Vesting Date and (ii) the date of Grantee’s termination, and the denominator of which is the number of months between (x) the later of the Grant Date or the most recent Vesting Date and (y) and the final Vesting Date.

(d) If, within the twenty-four (24)-month period following the occurrence of a Change in Control (as defined below), (A) the Grantee’s Employment is terminated by the Company other than for Cause or, (B) if the Grantee is a current member of the Company’s executive leadership team and is subjecttoaneffectiveemploymentorotherindividualagreement withtheCompanythatprovidestheGranteewiththeabilitytoterminatehis or her employment for “good reason” (with such term having the meaning ascribed thereto in the employment or other individual agreement, if any, between the Grantee and the Company for so long as such agreement is in effect), upon such termination and in lieu of the treatment provided for in Section 3(c)ii above,

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Exhibit 10.6

the Award, to the extent then outstanding, will immediately vest in full as to the total number of Cash Units subject to theAward on the date of termination.

i. ForpurposesofthisAgreement,“ChangeinControl”meansthefirst to occur of any of the followingevents:

1. an event in which any “person,” as such term is used in Sections 13(d) and 14(d) of the U.S. Securities Exchange Act of 1934, as amended(the“1934 Act”)(otherthan(A)theCompany,(B)any subsidiaryoftheCompany,(C)anytrusteeorotherfiduciary holding securities under an employee benefit plan of the CompanyorofanysubsidiaryoftheCompany,and(D)any company owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as theirownershipofstockoftheCompany),isorbecomesthe “beneficial owner” (as defined in Section 13(d) of the 1934 Act),togetherwithallaffiliatesandassociates(assuchterms areusedinRule12b-2oftheGeneralRulesandRegulations underthe1934Act)ofsuchperson,directlyorindirectly,of securities of the Company representing 40% or more of the combined voting power of the Company’s then outstanding securities;

2. the consummation of the merger or consolidation of the Company with any other company, other than (i) a merger or consolidation which would result in the voting securities of the Company outstanding immediately prior thereto continuing to represent (either by remaining outstanding or by being converted into voting securities of the surviving entity), in combination with the ownership of any trustee or otherfiduciaryholdingsecuritiesunderanemployeebenefit plan of the Company or any subsidiary of the Company, more than 50% of the combined voting power of thevoting securities of the Company or such surviving entity outstanding immediately after such merger or consolidation and (ii) a merger or consolidation effected to implement a recapitalizationoftheCompany(orsimilartransaction)after which no “person” “beneficially owns” (with the determination of such “beneficial ownership” on the same basisassetforthinclause(1)ofthisdefinition)securitiesof the Company or the surviving entity of such merger or consolidation representing 50% or more of the combined voting power of the securities of the Company or the surviving entity of such merger or consolidation;or

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Exhibit 10.6

3. the complete liquidation of the Company or the sale or disposition by the Company of all or substantially all of the Company’sassets.

Notwithstanding the foregoing, to the extent any amount constituting “nonqualified deferred compensation” subject to Section409AwouldbecomepayableundertheAwardbyreason ofaChangeinControl,itshallbecomepayableonlyiftheevent or circumstances constituting the Change in Control would also constitute a change in the ownership or effective control of the Company, or a change in the ownership of a substantial portion of the Company’s assets, within the meaning of subsection (a)(2)(A)(v) of Section 409A and the Treasury Regulations thereunder.

4.Settlement of Cash Units.

(a) Except for Cash Units which vest early pursuant to Section 3, as soon as administratively practicable following each Vesting Date, the Company or an Affiliate shall make a cash payment in local currency, less any applicable tax withholding and/or any other required withholdings pursuant to Section 7 of this Agreement, to the Grantee in settlement of the Cash Units awarded by this Agreement equal to the number of the Grantee’s vested Cash Units multiplied by the Fair Market Value of a share of Stock on the Vesting Date, subject to Section 4(c). For purposes of the foregoing, the amount of the cash payment in local currency shall be determined using the USD and local currency conversion rate on the date of vesting, as determined by the Company in its sole discretion.

(b) “Fair Market Value” means, subject to section (c) below, as of any given date, the fair market value of a share of Stock on the immediately preceding date determined by such methods or procedures as may be established from time to time by the Company. Unless otherwise determined by the Company, the Fair Market Value of a share of Stock as of any date shall mean the closing trading price for a share of Stock as reported on the New York Stock Exchange (or on any national securities exchange on which the Stock is then listed) on such date or, if no such price is reported for that date, the closing date on the following date for which such prices were reported. Notwithstanding the foregoing, the Fair Market Value shall not be deemed to fall below $5.00.

(c) The Fair Market Value shall be subject to the following limits:

i. If Cash Units vest on the first Vesting Date, and the Fair Market Value on such Vesting Date exceeds $8.75, the settlement of vested Cash Units shall be calculated as if the Fair Market Value on such

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Exhibit 10.6

Vesting Date was exactly $8.75.

ii. If Cash Units vest on the second Vesting Date, and the Fair Market Value on such Vesting Date exceeds $16.00, the settlement of vested Cash Units shall be calculated as if the Fair Market Value on such Vesting Date was exactly $16.00.

iii. If Cash Units vest on the third Vesting Date, and the Fair Market Value on such Vesting Date exceeds $23.25, the settlement of vested Cash Units shall be calculated as if the Fair Market Value on such Vesting Date was exactly $23.25.

iv. If Cash Units vest prior to a Vesting Date pursuant to Section 3(c)ii, the Fair Market Value on such early vesting date shall be equal to the Fair Market Value applicable to the next Vesting Date as described in (i)-(iii) above.

v. If Cash Units vest prior to a Vesting Date pursuant to Section 3(d), the Fair Market Value on such early vesting date shall be equal to the Fair Market Value on the date of vesting.

5.Forfeiture; Recovery of Compensation.ByacceptingtheAwardtheGrantee expressly acknowledges and agrees that his or her rights (and those of any permitted transferee) under the Award or any proceeds from the settlement thereof, are subject to Section 6(a)(5) of the Plan (including any successor provision). Without limiting the foregoing, the Administrator may recover Cash Units, or amounts paid upon settlement of Cash Units, in accordance with the Company’s Policy for Recoupment of Incentive Compensation (as may be amended from time to time) or as otherwise required by applicable law or applicable stock exchange listing standards. Nothing in the preceding sentence shall be construed as limiting the general application of Section 11 of thisAgreement.

6.Nontransferability. Neither the Award nor the Cash Units, nor any rights and privileges pertaining thereto, may be transferred except at death in accordance with Section 6(a)(3) of thePlan.

7.Responsibility for Taxes & Withholding. Regardless of any action the Company or any of its Affiliates takes with respect to any or all income tax, social insurance, payroll tax, payment on account or other tax-related items related to the Grantee’s participation in the Plan and legally applicable to the Grantee (“Tax-Related Items”), the Grantee acknowledges that the ultimate liability for all Tax-Related Items is and remains the Grantee’s responsibility and may exceed the amount actually withheld by theCompanyoranyofitsAffiliates.TheGranteefurtheracknowledgesthattheCompany and/oritsAffiliates(a)makenorepresentationsorundertakingsregardingthetreatmentof any Tax-Related Items in connection with any aspect to the Cash Units, including,butnotlimitedto,the

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Exhibit 10.6

grant,vestingorsettlementoftheCash Units, and the receipt of any dividend equivalents;and(b)donotcommittoandareundernoobligationtostructurethetermsof anyAwardtoreduceoreliminateGrantee’sliabilityforTax-RelatedItemsorachieveany particular tax result. Further, if the Grantee becomes subject to tax in more than one jurisdictionbetweenthedateofgrantandthedateofanyrelevanttaxableevent,theGrantee acknowledges that Company and/or its Affiliates may be required to withhold or account for Tax-Related Items in more than onejurisdiction.

Prior to any relevant taxable or tax withholding event, as applicable, the Grantee will pay or make adequate arrangements satisfactory to the Company and/or its Affiliates tosatisfyallTax-RelatedItems.Inthisregard,theGranteeauthorizestheCompanyand/or its Affiliates, or their respective agents, at their discretion, to satisfy the obligations with regard to all Tax-Related Items by one or a combination of thefollowing:

(a) withholding from the Grantee’s wages/salary or other cash compensation paid to the Grantee by the Company and/or its Affiliates;or

(b) withholding from gross amount of the cash payment in settlement of the Cash Units.

To avoid negative accounting treatment, the Company and/or its Affiliates may withhold or account for Tax-Related Items by considering applicable minimum statutory withholding amounts or other applicable withholding rates.

The Grantee shall pay to the Company and/or its Affiliates any amount of Tax- Related Items that the Company and/or its Affiliates may be required to withhold or accountforasaresultoftheGrantee’sparticipationinthePlanthatwillnotforanyreason besatisfiedbythemeanspreviouslydescribed.TheCompanymayrefuseto issue payment for the vested Cash Units if the Grantee fails to comply with the Grantee’s obligations in connection with the Tax-RelatedItems.

By accepting this grant of Cash Units, the Grantee expressly consents to the methods of withholding Tax-Related Items by the Company and/or its Affiliates as setforthherein,includingthewithholdingofproceeds andthewithholdingfromtheGrantee's wages/salaryorotheramountspayabletotheGrantee.AllotherTax-RelatedItemsrelated to the Cash Units and any payments issued therefor are the Grantee's soleresponsibility.

8.Other Tax Matters. If,atthetimeoftheGrantee’sterminationofemployment,theGranteeisa “specified employee,” as defined below, to the extent required by Section 409A, any and all amounts payable on account of the Grantee’s separation from service that constitute deferred compensation and would (but for this provision) be payable within six (6) months following the date of termination, shall instead be paid on the next business day following the expiration of such six (6) month period or, if earlier, upon the Grantee’s death. For purposes of this Agreement, all references to “termination of employment” and correlative phrases shall be construed to require a

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Exhibit 10.6

“separation from service” (as defined in Treasury Regulations section 1.409A-1(h) after giving effect to the presumptions contained therein), and the term “specified employee” means an individual determined bythe Company to be a specified employee under Treasury Regulation section 1.409A-1(i). Each payment made under this Agreement shall be treated as a separate payment and the right to a series of installment payments under this Agreement is to be treated as a right to a series of separate payments.

9.Effect on Employment. Neither the grant of the Cash Units,nor the payment upon vesting of any portion thereof, will give the Grantee any right to be retained in the employ or service of the Company or any of its Affiliates, affect the rightoftheCompanyoranyofitsAffiliatestodischargeordisciplinesuchGranteeatany time, or affect any right of such Grantee to terminate his or her Employment at anytime.

10.Acknowledgements. By accepting the Award, the Grantee agrees to be bound by, and agrees that the Award and the Cash Units are subject in all respects to, the terms of the Plan. The Grantee further acknowledges and agrees that (i) this Agreement may be executed in two or more counterparts, each of which shall be an original and all of which together shall constitute one and the same instrument, (ii) this agreement may be executed and exchanged using facsimile, portable document format (PDF)orelectronicsignature,which,ineachcase,shallconstituteanoriginalsignaturefor allpurposeshereunderand(iii)suchsignaturebytheCompanywillbebindingagainstthe Company and will create a legally binding agreement when this Agreement is countersigned by theGrantee or accepted electronically by the Grantee.

11.Authorization to Release and Transfer Necessary Personal Information. The Grantee hereby explicitly and unambiguously consents to the collection, use and transfer,inelectronicorotherform,ofhisorherpersonaldatabyandamong,asapplicable, the Company and the Affiliates for the exclusive purpose of implementing, administering and managing the Grantee’s participation in the Plan. The Grantee understands that the Company and the Affiliates may hold certain personal information about the Grantee including, but not limited to, the Grantee’s name, home address and telephone number, dateofbirth,socialsecuritynumber(oranyothersocialornationalidentificationnumber), salary, nationality, job title, number of Cash Units held and the details of all Cash Units awarded, cancelled, vested, unvested or outstanding for the purpose of implementing, administering and managing the Grantee’s participation in the Plan (the “Data”). The Grantee understands that the Data may be transferred to the Company or any of the Affiliates, or to any third parties assisting in the implementation, administration and management of the Plan, that these recipients may be located in the Grantee’s country or elsewhere, and that any recipient’s country (e.g., the United States) may have different data privacy laws and protectionsthantheGrantee’scountry.TheGranteeunderstandsthatheorshemayrequest alistwiththenamesandaddressesofanypotentialrecipientsoftheDatabycontactinghis or her local human resources representative. The Grantee authorizes the recipients to receive, possess, use, retain and transfer the Data, in electronic or other form, for the sole purposeofimplementing,administeringandmanaginghisorherparticipationinthePlan, including any requisite transfer of such Data to a broker or other third party assisting with the administration of Cash Units under the Plan or with whom cash from the

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Exhibit 10.6

vesting of such Cash Units may be deposited.Furthermore, the Grantee acknowledges and understands that the transferoftheDatatotheCompanyortheAffiliatesortoanythirdpartiesisnecessaryfor hisorherparticipationinthePlan.TheGranteeunderstandsthatDatawillbeheldonlyas long as is necessary to implement, administer and manage his or her participation in the Plan. The Grantee understands that he or she may, at any time, view the Data, request additionalinformationaboutthestorageandprocessingoftheData,requireanynecessary amendmentstotheDataorrefuseorwithdrawtheconsentshereinbycontactinghisorher local human resources representative in writing. The Grantee further acknowledges that withdrawal of consent may affect his or her ability to vest in or realize benefits from the Cash Units, and his or her ability to participate in the Plan. For more information on the consequences of refusal to consent or withdrawal of consent, the Grantee understands that he or she may contact his or her local human resources representative.

Finally, upon request of the Company or the Grantee’s employer (the “Employer”), the Grantee agrees to provide an executed data privacy consent form (or any other agreements or consents that may be required by the Company and/or the Employer) that the Company and/or the Employer may deem necessary to obtain from the Grantee forthepurposeofadministeringtheGrantee’sparticipationinthePlanincompliancewith the data privacy laws in the Grantee’s country, either now or in the future. The Grantee understands and agrees that the Grantee will not be able to participate in the Plan if the Grantee fails to provide any such consent or agreement requested by the Company and/or the Employer.

12.Electronic Delivery and Execution. The Grantee hereby consents and agrees to electronic delivery of any documents that the Company may elect to deliver (including, but not limited to, plan documents, prospectus and prospectus supplements, grant or award notifications and agreements, account statements, annual and quarterly reports, and all other forms of communications) in connection with this and any other Award made or offered under the Plan. The Grantee understands that, unless revoked by theGranteebygivingwrittennoticetotheCompanypursuanttothePlan,thisconsentwill beeffectiveforthedurationoftheAgreement.TheGranteealsounderstandsthatheorshe will have the right at any time to request that the Company deliver written copies of any andallmaterialsreferredtoabove.TheGranteeherebyconsentstoanyandallprocedures the Company has established or may establish for an electronic signature system for deliveryandacceptanceofanysuchdocumentsthattheCompanymayelecttodeliver,and agree that his or her electronic signature is the same as, and will have the same force and effect as, his or her manual signature. The Grantee consents and agrees that any such procedures and delivery may be affected by a third party engaged by the Company to provide administrative services related to thePlan.

13.Appendix. Notwithstanding any provision of the Agreement to the contrary, this Cash Unit grant shall be subject to any and all special terms and provisions as set forth in the Appendix, if any, for the Grantee’s country of residence (and country of employment, ifdifferent). Moreover, if the Grantee relocates to one of the countries included in the Appendix, the additional terms and conditions for such country will apply to the Grantee, to the extent the Company determines that the application of such terms and conditions is

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Exhibit 10.6

necessary or advisable for legal or administrative reasons.  The Appendix constitutes part of the Agreement.

14.Severability.TheprovisionsofthisAgreementareseverableandifanyone or more provisions are determined to be illegal or otherwise unenforceable, in whole or in part, the remaining provisions shall nevertheless be binding andenforceable.

[Signature page follows.]

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Exhibit 10.6

IN WITNESS WHEREOF, the Company has caused this Agreement to be executed by its duly authorized officer.

TRINSEO PLC

By:

Name:

Title:

Dated:

Acknowledged and Agreed:

By:

Signature Page to Cash Unit Agreement

Exhibit 10.6

COUNTRY APPENDIX

ADDITIONAL TERMS AND CONDITIONS TO CASH UNIT AGREEMENT

ThisCountryAppendix(“Appendix”)includesthefollowingadditionaltermsandconditionsthat governtheGrantee’sCashUnitAwardforall the Granteesthatresideand/orworkoutside of the UnitedStates.

Notifications

This Appendix also includes information regarding exchange controls and certain other issuesofwhichtheGranteeshouldbeawarewithrespecttotheGrantee’sparticipationinthePlan. The information is based on the securities, exchange control and other laws in effect in the respective countries as of January 2024. Such laws are often complex and change frequently. Asaresult,theCompanystronglyrecommendsthattheGranteenotrelyontheinformationinthis AppendixastheonlysourceofinformationrelatingtotheconsequencesoftheGrantee’s participationinthePlanbecausetheinformationmaybeoutofdateatthetimethattheCash Units vest or payment is made in settlement of the Cash Units.

In addition, the information contained herein is general in nature and may not apply to the Grantee’sparticularsituation,andnoneoftheCompany,itsAffiliates,northeAdministratorisin a position to assure the Grantee of a particular result. Accordingly, the Grantee is advised to seek appropriate professional advice as to how the relevant laws in the Grantee’s country of residence and/or work may apply to the Grantee’ssituation.

Finally, if the Grantee transfers employment after the Grant Date, or is considered a resident of anothercountryforlocallawpurposesfollowingtheGrantDate,thenotificationscontainedherein may not be applicable to the Grantee, and the Administrator shall, in its discretion, determine to what extent the terms and conditions contained herein shall be applicable to theGrantee.

Terms and Conditions Applicable to All Non-U.S. Jurisdictions

English Language. The Grantee acknowledges and agrees that it is the Grantee’s express intent that this Agreement, the Plan and all other documents, rules, procedures, forms, notices and legal proceedingsenteredinto,givenorinstitutedpursuanttothe CashUnitAward,bedrawn upinEnglish.IftheGranteehasreceivedthisAgreement,thePlanoranyotherrules,procedures, forms or documents related to the Cash Unit Award translated into a language other thanEnglish,andifthemeaningofthetranslatedversionisdifferentthantheEnglishversion,the English version willcontrol.

Exchange Control, Foreign Asset/Account and/or Tax Reporting.  Depending upon the country to which laws the Grantee is subject, the Grantee may have certain foreign asset/account and/or tax reporting requirements that may affect the Grantee’s ability to acquire cash received from participating in the Plan (including from any dividend equivalents) in a brokerage or bank account outside the Grantee’s country of residence. The Grantee’s country may require that the Grantee reports such accounts, assets or transactions to the applicable authorities in his or her country. The Grantee also may be required to repatriate cash received from participating in the Plan to the Grantee’s country within a certain period of time after receipt. The Grantee is responsible for knowledge of and compliance with any such regulations and should speak with his or her personal

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Exhibit 10.6

tax, legal and financial advisors regarding same.

Commercial Relationship. The Grantee expressly recognizes that the Grantee’s participation in thePlanandtheCompany’sAwardgrantdoesnotconstituteanemploymentrelationshipbetween the Grantee and the Company. The Grantee has been granted Cash Units as a consequence of the commercial relationship between the Company and the Employer, and the Employer is the Grantee’s sole employer. Based on the foregoing, (a) the Grantee expressly recognizes the Plan and the benefits the Grantee may derive from participation in the Plan do not establish any rights between the Grantee and the Affiliate that employs the Grantee, (b) the Plan and the benefits the Grantee may derive from participation in the Plan are not part of the employmentconditionsand/orbenefitsprovidedbytheAffiliatethatemploystheGrantee,and(c) any modifications or amendments of the Plan by the Company or the Administrator, or a termination of the Plan by the Company, shall not constitute a change or impairment of the terms and conditions of the Grantee’s employment with the Affiliate that employs theGrantee.

Additional Acknowledgements. The GRANTEE also acknowledges and agrees to the following:

● ThePlanisestablishedvoluntarilybytheCompany,itisdiscretionaryinnature,anditmay bemodified,amended,suspendedorterminatedbytheCompanyatanytime,totheextent permitted by thePlan.

● All decisions with respect to future Awards or other grants, if any, will be at the sole discretion of theCompany.

●The future Fair Market Value of the Stock is unknown, undeterminable and cannot be predicted withcertainty.

●The Grantee’s participation in the Plan isvoluntary.

● No claim or entitlement to compensation or damages arises from the forfeiture of the Award or any of the Cash Units, the termination of the Plan, or the diminution in value of the Cash Units, and the Grantee irrevocably releases the Company,itsAffiliates,theAdministratorandtheiraffiliatesfromanysuchclaimthatmay arise.

● TheCash Unit,andtheincomeandvalueofsame,arenot part of normal or expected compensation or salary for purposes of, including but not limited to, calculating any severance, resignation, termination, redundancy, dismissal, end-of-service payments, bonuses, holiday pay, long-service awards, pension or retirement or welfare benefits or similarpayments, and are not for the purpose of, arenotintendedto replace, any pension rights orcompensation.

● UnlessotherwiseagreedwiththeCompanyinwriting,theAward, and the income and value of same, are not granted as consideration for, or in connection with, any service the Grantee may provide as a director of the Company or its Affiliates.

● Neither the Company nor its Affiliates shall be liable for any foreign exchange rate fluctuation between the Grantee's local currency and the U.S. Dollar that may affect the value

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Exhibit 10.6

of the Cash Units or of any amounts due to the Grantee pursuant to the settlement oftheCash Units.

● None of the Company, its Affiliates, nor the Administrator is providing any tax, legal or financial advice or making any recommendations regarding the Grantee’s participation in the Plan, the grant, vesting or settlement of the Grantee’s Cash Units. The Grantee is hereby advised to consult with his own personal tax, legal and financialadvisorsregardinghisparticipationinthePlanbeforetakinganyactionrelatedto thePlan.

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Exhibit 10.6

EUROPEAN UNION (“EU”) / EUROPEAN ECONOMIC AREA (“EEA”) / SWITZERLAND / UNITED KINGDOM

Terms and Conditions

Employee Data Privacy. If the Grantee resides and/or works in the EU/EEA, Switzerland or the United Kingdom, the following provisions replace Section 11 of the Agreement in its entirety:

The Company, with its address at 440 E. Swedesford Road, Suite 301, Wayne, PA 19087, USA, is the controller responsible for the processing of the Grantee’s personal data by the Company and the third parties noted below, and itsrepresentativeinItalyforprivacypurposes is A.P.I. Applicazioni Plastiche Industriali S.p.A. with its registered address at Via Dante Alighieri n. 27, 36065 Mussolente (VI)Italy.

(a)Data Collection and Usage. Pursuant to applicable data protection laws, the Grantee is hereby notified that the Company collects, processes and uses certain personally-identifiable information about the Grantee for the legitimate interest of implementing, administering and managing the Plan and generally administering equity awards; specifically, including the Grantee’s name, home address, email address and telephone number, date of birth, social insurance number or other identification number, salary, citizenship, job title, any shares of Stock or directorships held in the Company, and details of all Cash Units awarded, vested, or outstanding in the Grantee’s favor, which the Company receives from the Grantee or the Grantee’s employer (“Personal Data”). In granting the Cash Units under the Plan, the Company will collect Personal Data for purposes of implementing, administering and managing the Plan. The Company’s legal basis for the collection, processing and use of Personal Data is the necessity of the processing for the Company to perform its contractual obligations under the Agreement and the Plan and the Company’s legitimate business interests of managing the Plan, administering employee equity awards and complying with its contractual and statutory obligations.

(b)Stock Plan Administration Service Provider. The Company transfers Personal Data to Merrill Lynch and its affiliates, an independent service provider based in the United States, which assists the Company with the implementation, administration and management of the Plan. In the future, the Company may select a different service provider and share Personal Data with another company that serves in a similar manner. The Grantee will be asked to agree on separate terms and data processing practices with the service provider, which is a condition to the Grantee’s ability to participate in the Plan. The processing of Personal Data will take place through both electronic and non-electronic means. Personal Data will only be accessible by those individuals requiring access to it for purposes of implementing, administering and operating the Plan.

(c)International Data Transfers. The Company and its service providers are based in the United States or elsewhere throughout the world. The Grantee’s country or jurisdiction may have different data privacy laws and protections than the United States. The Company's legal basis for the transfer of the Grantee’s Personal Data to the United States is to satisfy its contractual obligations under the terms and conditions of this Agreement.

(d)Data Retention. The Company will use Personal Data only as long as is necessary to implement, administer and manage the Grantee’s participation in the Plan or as required to comply with legal or regulatory obligations, including tax and securities laws. When the Company no longer needs Personal Data, the Company will remove it from its systems. If the Company keeps Personal

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Exhibit 10.6

Data longer, it would be to satisfy legal or regulatory obligations and the Company’s legal basis would be for compliance with relevant laws or regulations.

(e)Data Subject Rights. The Grantee may have a number of rights under data privacy laws in the Grantee’s country. For example, the Grantee’s rights may include the right to (i) request access or copies of Personal Data the Company processes, (ii) request rectification of incorrect Personal Data, (iii) request deletion of Personal Data, (iv) place restrictions on processing of Personal Data, (v) lodge complaints with competent authorities in the Grantee’s country, and/or (vi) request a list with the names and addresses of any potential recipients of Personal Data. To receive clarification regarding the Grantee’s rights or to exercise the Grantee’s rights, the Grantee may contact his or her local partner or human resources representative.

FRANCE

Terms and Conditions

Use of English Language. Les parties reconnaissent avoir exigé la rédaction en anglais de la présente convention, ainsi que de tous documents exécutés, avis donnés et procédures judiciaires intentées, directement ou indirectement, relativement à ou suite à la présente convention.

HONG KONG

Terms and Conditions

Not subject to ORSO. The Company specifically intends that the Plan will not be an occupationalretirementschemeforpurposesoftheOccupationalRetirementSchemesOrdinance (ORSO).

ITALY

Terms and Conditions

Plan Document Acknowledgment. The Grantee further acknowledges that he or she has read and specifically and expressly approves the Data Privacy section above as well as the following sections of the Agreement Section 1 (“Grant of Cash Units”); Section 3 (“Vesting”); Section 4 (“Settlement of Cash Units”), Section 5 (“Forfeiture; Recovery of Compensation”); Section 6 (“Nontransferability”); Section 7 (“Responsibility for Taxes & Withholding”); Appendix (“English Language”; “Additional Acknowledgements”).

MEXICO

Terms and Conditions

Plan Document Acknowledgement. By accepting the Cash Units, the Grantee acknowledges that he or she has received a copy of the Plan and the Agreement, including this Appendix, which the Grantee has reviewed. The Grantee acknowledges further that he or she accepts all the provisions of the Plan and the Agreement, including this Appendix. The Grantee also acknowledges that he or she has read and specifically and expressly approves the terms and conditions set forth in “Additional Acknowledgements” in this Appendix, which clearly provides as follows:

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Exhibit 10.6

(1)The Grantee’s participation in the Plan does not constitute an acquired right;

(2)The Plan and the Grantee’s participation in it are offered by the Company on a wholly discretionary basis;

(3)The Grantee’s participation in the Plan is voluntary; and

(4)Neither the Company nor any Affiliates are responsible for any decrease in the value of the Award granted and/or cash paid under the Award.

Labor Law Policy and Acknowledgment

By accepting the Cash Units, the Grantee expressly recognizes that the Company, with registered offices at Riverside One, Sir John Rogerson’s Quay, Dublin 2, Dublin, Ireland D02 X576, is solely responsible for the administration of the Plan and that the Grantee’s participation in the Plan and acquisition of Stock do not constitute an employment relationship between the Grantee and the Company since the Grantee is participating in the Plan on a wholly commercial basis and his or her sole employer is Trinseo de Mexico, S. de R.L. de C.V. or Altuglas Mexico S.A. de C.V. (together, “Trinseo Mexico”). Based on the foregoing, the Grantee expressly recognizes that the Plan and the benefits that he or she may derive from participating in the Plan do not establish any rights between the Grantee and the employer, Trinseo Mexico, and do not form part of the employment conditions and/or benefits provided by Trinseo Mexico, and any modification of the Plan or its termination shall not constitute a change or impairment of the terms and conditions of the Grantee’s employment.

The Grantee further understands that his or her participation in the Plan is as a result of a unilateral and discretionary decision of the Company; therefore, the Company reserves the absolute right to amend and/or discontinue the Grantee’s participation at any time without any liability to the Grantee.

Finally, the Grantee hereby declares that he or she does not reserve to him- or herself any action or right to bring any claim against the Company for any compensation or damages regarding any provision of the Plan or the benefits derived under the Plan, and the Grantee therefore grants a full and broad release to the Company, and its subsidiaries, branches, representative offices, shareholders, directors, officers, employees, agents, or legal representatives with respect to any claim that may arise.

Spanish Translation

Reconocimiento del Documento del Plan

Al aceptar las Unidades de Efectivo, el Beneficiario reconoce que ha recibido una copia del Plan y el Acuerdo, con inclusión de este Anexo, que el Beneficiario ha revisado. El Beneficiario reconoce, además, que acepta todas las disposiciones del Plan y en el Acuerdo, incluyendo este Anexo. El Beneficiario también reconoce que ha leído y que concretamente aprueba de forma expresa los términos y condiciones establecidos en la Sección “Reconocimientos Adicionales” de este Anexo, que claramente dispone lo siguiente:

(1)La participación del Beneficiario en el Plan no constituye un derecho adquirido;

(2)El Plan y la participación del Beneficiario en el Plan se ofrecen por la Compañía en su discrecionalidad total;

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Exhibit 10.6

(3)Que la participación del Beneficiario en el Plan es voluntaria; y

(4)Ni la Compañía ni sus Afiliadas son responsables por la reducción del valor del Premio y/o el efectivo pagado en virtud del Premio.

Política Laboral y Reconocimiento

Al aceptar las Unidades de Efectivo, el Beneficiario expresamente reconoce que la Compañía, con sus oficinas registradas y ubicadas en Riverside One, Sir John Rogerson’s Quay, Dublin 2, Dublin, Ireland D02 X576, es la única responsable por la administración del Plan y que la participación del Beneficiario en el Plan y en su caso la adquisición de Acciones no constituyen una relación de trabajo entre el Beneficiario y la Compañía, ya que el Beneficiario participa en el Plan en un marco totalmente comercial y su único patrón es Trinseo de Mexico, S. de R.L. de C.V. o Altuglas Mexico S.A. de C.V. (juntos, “Trinseo Mexico”). Derivado de lo anterior, el Beneficiario expresamente reconoce que el Plan y los beneficios que pudieran derivar de la participación en el Plan no establecen derecho alguno entre el Beneficiario y el patrón, Trinseo Mexico, y no forma parte de las condiciones de trabajo y/o las prestaciones otorgadas por Trinseo Mexico, y que cualquier modificación al Plan o su terminación no constituye un cambio o desmejora de los términos y condiciones de la relación de trabajo del Beneficiario.

Asimismo, el Beneficiario reconoce que su participación en el Plan se ha resultado de una decisión unilateral y discrecional de la Compañía; por lo tanto, la Compañía se reserva el derecho absoluto de modificar y/o terminar la participación del Beneficiario en cualquier momento y sin responsabilidad alguna frente el Beneficiario.

Finalmente, el Beneficiario por este medio declara que no se reserva ninguna derecho o acción en contra de la Compañía por cualquier compensación o daños y perjuicios en relación de las disposiciones del Plan o de los beneficios derivados del Plan, y por lo tanto, el Beneficiario otorga el más amplio finiquito que en derecho proceda a la Compañía, y sus filiales, oficinas de representación, accionistas, directores, autoridades, empleados, agentes, o representantes legales en relación con cualquier demanda que pudiera surgir.

NETHERLANDS

Terms and Conditions

Waiver of Termination Rights.  In consideration of the grant of the Cash Units, the Grantee agrees that he or she waives any and all rights to compensation or damages as a result of any termination of employment for any reason whatsoever, insofar as those rights result or may result from (a) the loss or diminution in value of such rights or entitlements under the Plan, or (b) the Grantee ceases to have rights under, or ceasing to be entitled to any awards under the Plan as a result of such termination.

SPAIN

Terms and Conditions

Nature of Award. In accepting the grant of Cash Units, the Grantee acknowledges that he or she consents to participation in the Plan and has received a copy of the Plan.

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Exhibit 10.6

The Grantee understands that the Company has unilaterally, gratuitously and discretionally decided to grant Cash Units under the Plan to individuals who may be employees of the Company or its Affiliates throughout the world. The decision is a limited decision that is entered into upon the express assumption and condition that any grant will not economically or otherwise bind the Company or any of its Affiliates over and above the specific terms of the Plan. Consequently, the Grantee understands that the Cash Units are granted on the assumption and condition thattheCash Units and any cash received in connection with such Awards shall not become a part of any employment contract (either with the Company or any of its Affiliates) and shall not be considered a mandatory benefit, salary for any purposes (including severance compensation) or any other right whatsoever.

Further, the Grantee understands and agrees that, unless otherwise expressly provided for by the Company or set forth in the Agreement, the Cash Units will be cancelled without entitlement to any Stock if the Grantee ceases to be an eligible participant for any reason, including, but not limited to: resignation, disciplinary dismissal adjudged to be with cause, disciplinary dismissal adjudged or recognized to be without good cause (i.e., subject to a “despido improcedente”), material modification of the terms of employment under Article 41 of the Workers’ Statute, relocation under Article 40 of the Workers’ Statute, Article 50 of the Workers’ Statute, or under Article 10.3 of Royal Decree 1382/1985.  The Company, in its sole discretion, shall determine the date when the Grantee’s status as an eligible participant has terminated for purposes of the Cash Units.

In addition, the GranteeunderstandsthatthisgrantwouldnotbemadetotheGranteebutfortheassumptionsand conditions referred to above; thus, the Grantee acknowledges and freely accepts that should any or all of the assumptions be mistaken or should any of the conditions not be met for any reason, then any grant of Cash Units shall be null andvoid.

UNITED KINGDOM

Terms and Conditions

Tax Withholding and National Insurance Contributions Acknowledgement. Notwithstanding any provisions in the Agreement, the Grantee agrees that he or she is liable for all Tax-Related Items andherebycovenantstopayallsuchTax-RelatedItems,asandwhenrequestedbytheCompany, the Employer, or by His Majesty’s Revenue and Customs (“HMRC”) or any other tax authority or other relevant authority. The Grantee also agrees to indemnify and keep indemnified the Company and the Employer against any Tax-Related Items that they are required to pay or withhold,orhavepaidorwillpay,toHMRC(oranyothertaxauthorityorotherrelevantauthority) on the Grantee’sbehalf.

Notwithstanding the foregoing, if the Grantee is a director or executive officer of the Company (within the meaning of Section 13(k) of the U.S. Securities Exchange Act of 1934, as amended), the terms of the immediately foregoing provision may not apply to the Grantee if the indemnification is viewed as a loan. In this case, if the amount of anyincometax due is notcollected from orpaid by the Grantee within ninety (90) days of the end of the U.K. tax yearin which an event giving rise to the indemnification described above occurs, the amount of any uncollected income taxmayconstitutean additional benefit to the Grantee on which additional income tax and national insurance contributions (“NICs”) may be payable. The Grantee will be responsible for reporting and paying any income tax due on this additional benefit directly to HMRC under the self-assessment regime and for payingtotheCompanyortheEmployer,asapplicable,anyemployeeNICsdueonthisadditional benefit, which the Company or the Employer may recover from the Grantee by any of the

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Exhibit 10.6

means referred to in Section 8 of theAgreement.

Exclusion of Claim. The Grantee acknowledges and agrees that the Grantee will have no entitlement to compensation or damages insofar as such entitlement arises or may arise from the Grantee’s ceasing to have rights under or to be entitled to the Cash Units, whether or not as a result of termination of Grantee’s Employment (whether the termination is in breach of contractorotherwise),orfromthelossordiminutioninvalueoftheCash Units.Upon the grant of the Cash Units, the Grantee shall be deemed to have waived irrevocably any suchentitlement.

***

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EX-10.7

Exhibit 10.7

TRINSEO NETHERLANDS B.V.

EMPLOYMENT AGREEMENT

EMPLOYMENT AGREEMENT (this “Agreement”), dated as of August 5, 2022, is among Trinseo Netherlands B.V., a Dutch limited liability company (Besloten vennootschap met beperkte aansprakelijkheid) (the “Company”), and JOHANNES (also known as “HAN”) LAMBERTUS HENDRIKS (the “Executive”).

W I T N E S S E T H

WHEREAS, the Company desires to employ the Executive as Senior Vice President, Chief Technology Officer of the Company and to pay all of the Executive’s compensation and other benefits described in this Agreement; and

WHEREAS, the Company and the Executive desire to update the terms and conditions of such employment by entering into this Agreement which shall define the terms of the Executive’s employment with the Company.

NOW, THEREFORE, in consideration of the foregoing, of the mutual promises con­tained herein and of other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as follows:

1.POSITION AND DUTIES.

(a)During the Employment Term (as defined in Section 2 hereof), the Executive shall serve as Senior Vice President, Chief Technology Officer of the Company and its ultimate parent company, Trinseo PLC (“Parent”).  In this capacity, the Executive shall have the duties, authorities and responsibilities commensurate with the duties, authorities and responsibilities of persons in similar capacities in similarly sized companies, and such other executive duties, authorities and responsibilities as may reasonably be assigned to the Executive that are not inconsistent with the Executive’s position as Senior Vice President, Chief Technology Officer of the Company and the Parent. The Executive’s principal place of employment with the Company shall be a virtual home office in The Netherlands, or such other location as may be mutually agreed upon; provided that the Executive understands and agrees that the Executive will be required to travel frequently for business purposes including travel to Switzerland for key meetings and decision making regarding the generation and management of intellectual property owned by the Company’s affiliate Trinseo Europe GmbH. The Executive shall report directly to the President and Chief Executive Officer or a named executive officer of the Parent.

(b)During the Employment Term, the Executive shall devote all of the Executive’s business time, energy, business judgment, knowledge and skill and the Executive’s reasonable best efforts to the performance of the Executive’s duties with the Company and the Parent, provided that the foregoing shall not prevent the Executive from (i) serving on the boards of directors of non-profit organizations and, with the prior written approval of the Board of the Parent (the “Board”), other for profit companies; provided that the Executive shall be permitted to serve on the board of directors of auto body parts supplier Visscher-Caravelle B.V., (ii) participating in

1

charitable, civic, educational, professional, community or industry affairs, and (iii) managing the Executive’s passive personal investments so long as such activities in the aggregate do not violate Section 10 hereof, interfere or conflict with the Executive’s duties hereunder or create a business or fiduciary conflict. Any overtime worked by the Executive is fully compensated by the Base Salary (as defined in Section 3).

2.EMPLOYMENT TERM. The Company agrees to employ the Executive pursuant to the terms of this Agreement commencing on October 1, 2022 (the “Effective Date”) for an indefinite period of time of which the first 6 (six) months shall be considered as trial period. The Company may terminate this Agreement by giving 6 (six) months' advance written notice such notice to expire on the last day of the relevant calendar month.  The Executive may terminate this Agreement by giving 3 (three) months’ advance written notice such notice to expire on the last day of the relevant calendar month. Notwithstanding the foregoing, the Executive’s employment hereunder may be earlier terminated in accordance with Section 6 hereof, subject to Section 7 hereof. The period of time between the Effective Date and the termination of the Executive’s employment hereunder shall be referred to herein as the “Employment Term.” This Agreement may be conditioned on any, or all of, the Executive: (i) passing a background check; (ii) passing a screening for illegal and controlled substances; and (iii) confirming employment eligibility; and (iv) providing the Company with the results of a recent physical examination or other evidence showing the absence of any conditions that would preclude the Executive from fulfilling the obligations contemplated in this Agreement.

3.BASE SALARY. During the Employment Term, the Company agrees to pay the Executive an annual base salary of not less than 490,000 EUR gross per annum, payable in accordance with the regular payroll practices of the Company, but not less frequently than monthly. The Executive’s base salary shall be subject to annual review by the Board (or a committee thereof) during the first ninety (90) days of each calendar year, and the base salary in respect of such calendar year may be increased above, but not decreased below, its level for the preceding calendar year, by the Board. The base salary as determined herein and adjusted from time to time shall constitute “Base Salary” for purposes of this Agreement.

4.ANNUAL BONUS.

(a)During the Employment Term, the Executive shall be eligible for an annual discretionary cash performance bonus (an “Annual Bonus”) in respect of each calendar year that ends during the Employment Term, to the extent earned based on performance against objective performance criteria. The performance criteria for any particular calendar year shall be determined in good faith by the Board, no later than ninety (90) days after the commencement of such calendar year. The Executive’s targeted Annual Bonus for a calendar year shall equal 60% of the Executive’s Base Salary for such calendar year (the “Target Bonus”) if target levels of performance for such year are achieved, with greater or lesser amounts (including zero) paid for performance above and below target (such greater and lesser amounts to be determined by a formula established by the Board for such year when it establishes the targets and performance criteria for such year); provided that the Executive’s maximum Annual Bonus for any calendar year during the Employment Term shall equal 200% of the Target Bonus for such calendar year.

2

(b)The Executive’s Annual Bonus for a calendar year shall be determined by, and is subject to the discretion of, the Board after the end of the applicable calendar year based on the level of achievement of the applicable performance criteria, and shall be paid to the Executive in the calendar year following the calendar year to which such Annual Bonus relates at the same time annual bonuses are paid to other senior executives of the Company, subject to continued employment at the time of payment (except as otherwise provided in Section 7 hereof).

(c)For calendar year 2022, the Executive’s participation in the Annual Bonus will be prorated.

5.EMPLOYEE BENEFITS.

(a)BENEFIT PLANS. During the Employment Term, the Executive shall be entitled to participate in any employee benefit plan that the Company has adopted or may adopt, maintain or contribute to and which benefit any of the senior executives of the Company, on a basis no less favorable than that applicable to any such senior executives, subject to satisfying the applicable eligibility requirements, except to the extent such plans are duplicative of the benefits otherwise provided hereunder. The Executive’s participation in any such employee benefit plan shall be subject to the terms of the applicable plan documents and generally applicable Company policies. Notwithstanding the foregoing, the Company may modify or terminate any employee benefit plan at any time, if and to the extent allowed pursuant to the terms of such plan, provided that any such amendment may have no more adverse effect on the Executive than on any other participant in such plan.  The Company may provide perquisites to the Executive at the discretion of the Board.

(b)VACATIONS. During the Employment Term, the Executive shall be entitled to paid vacation in accordance with the Company’s policy on accrual and use applicable to employees as in effect from time to time, currently calculated as twenty-seven (27) days annually for the Executive.

(c)BUSINESS EXPENSES. Upon presentation of reasonable substantiation and documentation as the Company may specify from time to time, the Executive shall be reimbursed in accordance with the Company’s expense reimbursement policies as in effect from time to time, for all reasonable out-of-pocket business expenses incurred and paid by the Executive during the Employment Term and in connection with the performance of the Executive’s duties hereunder.

(d)CASH SIGNING BONUS. In consideration of joining the Company and the forfeiture by the Executive of certain compensation at the Executive’s prior employer, the Company shall pay to the Executive a one-time lump sum cash payment in the amount of 250,000 EUR gross (the “Cash Signing Bonus”) which shall be payable as an advance on or before 31 March 2023 as part of the Company’s ordinary payroll cycle.  This Cash Signing Bonus shall become fully vested after two (2) years from the payment date, subject to the Executive’s continued and non-terminated employment with the Company.  In the event that the Executive’s employment with the Company terminates as a result of a termination by the Company for Cause or by the Executive without Good Reason at any time within a period of two (2) years following the payment date, the Executive shall be required to repay the pro-rata unvested portion of the advanced Cash Signing Bonus to the Company calculated using the number of months remaining in the two (2) years following the payment date. For example, the Executive would be required to repay 125,000

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EUR in the event employment with the Company terminates on the twelve-month anniversary of the payment date as a result of a termination by the Company for Cause or by the Executive without Good Reason. Such amount shall be repaid to the Company no later than thirty (30) days following such termination date and, at the Company’s election, the Company may offset such amount against any amount owed by the Company to the Executive.  For purposes of this Agreement, “Good Reason” shall mean the occurrence of any of the following events, without the express written consent of the Executive, unless such events are fully corrected in all material respects by the Company or Parent (as applicable) within thirty (30) days following written notification by the Executive to the Company of the occurrence of one of the reasons set forth below: (i) other than following the receipt of the Company's written notice pursuant to Section 7, the material diminution in the Executive’s position, duties or authorities or assignment of duties materially inconsistent with the Executive’s position with Parent, including but not limited to the Executive ceasing to be the sole Chief Technology Officer; (ii) the relocation of the Executives office location outside of The Netherlands; (iii) a reduction in Base Salary or Target Bonus; (iv) the Parent’s failure to grant Executive the Long Term Incentive Equity Awards set forth in a separate letter; or (v) the Company’s material breach of this Agreement. The Executive shall provide the Company with a written notice detailing the specific circumstances alleged to constitute Good Reason within ninety (90) days after the Executive first gains actual knowledge of the occurrence of such circumstances, and actually terminate employment within thirty (30) days following the expiration of the Company’s thirty (30)-day correction period described above. Otherwise, any claim of such circumstances as “Good Reason” shall be deemed irrevocably waived by the Executive.  For avoidance of doubt, succession planning or successor candidate evaluation by the Company, shall not, by itself, constitute Good Reason.

(e)CAR ALLOWANCE. During the Employment Term, the Executive shall be entitled to a monthly car allowance in the amount of 1,400 EUR paid via payroll less applicable taxes.

6.TERMINATION. Notwithstanding Section 2 above, the Executive’s employment and the Employment Term shall terminate on the first of the following to occur:

(a)DEATH. Automatically upon the date of death of the Executive.

(b)CAUSE. Immediately upon written notice by the Company to the Executive of a termination for cause ("dringende reden") as provided for in Dutch employment law ("Cause").  For the sake of clarity, to the extent not already provided for in Dutch law, Cause shall also include the following behaviors: (i) continued failure to cooperate in any audit or investigation of financial or business practices of the Company or Parent after written request for cooperation from the Board and a period of no less than ten (10) days to cure such failure; (ii) commission of any criminal act or other act involving moral turpitude, sexual harassment or drug violations (after an independent investigation concludes that such acts occurred and Executive has been presented with opportunity to participate in the investigation); (iii) commission of any willful act which brings public disrepute, contempt, scandal, or ridicule, or which shocks or offends the community or any group or class thereof, or which reflects unfavorably upon Company or Parent and, as a result of such act or involvement, reduces the commercial value of Company's or Parent’s association with Executive; or (iv) breach of any of the restrictive covenants set forth in Section 10 hereof or in any other written agreement between the Executive and the Company and/or its Affiliate that causes

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material and demonstrable harm to the Company or Parent and that is not cured within fifteen (15) days of written notice from the Board.

7.CONSEQUENCES OF TERMINATION.

(a)DEATH. In the event that the Executive’s employment and the Employment Term ends on account of the Executive’s death, the Executive or the Executive’s estate, as the case may be, shall be entitled to the following (with the amounts due under Sections 7(a)(i) through 7(a)(v) hereof to be paid, unless otherwise provided below, within sixty (60) days following termination of employment, or such earlier date as may be required by applicable law):

(i)any unpaid Base Salary through the date of termination;

(ii)any Annual Bonus earned but unpaid with respect to the calendar year end­ing on or preceding the date of termination;

(iii)an amount equal to the pro-rata portion of the Executive’s Target Bonus for the calendar year of termination (determined by multiplying the Target Bonus for the year of termination by a fraction, the numerator of which is the number of days during the calendar year of termination that the Executive is employed by the Company and the denominator of which is 365);

(iv)reimbursement for any unreimbursed business expenses incurred through the date of termination;

(v)payment in respect of any accrued but unused vacation time in accordance with Company policy;

(vi)all other payments, benefits or fringe benefits to which the Executive shall be entitled under the terms of any applicable compensation arrangement or benefit, or fringe benefit plan or program or grant or this Agreement (collectively, Sections 7(a)(i) through 7(a)(vi) hereof shall be hereafter referred to as the “Accrued Benefits”) and

(vii)if the Executive is survived by a spouse, a registered partner, children who are minors or, in the absence of such heirs, other persons to whom he/she had a duty to provide support, the Base Salary for one month or, if the Executive had completed more than five years of service, for two months;

(b)TERMINATION FOR CAUSE BY THE COMPANY; TERMINATION BY THE EXECUTIVE. If the Executive’s employment is terminated (x) by the Company for Cause or (y) by the Executive for whatsoever reason, the Company shall pay to the Executive the Accrued Benefits except for Section 7(a) (iii).  If the Executive terminates the Agreement, then the Company may elect to transition Executive’s duties and responsibilities to others during the notice period.

(c)TERMINATION WITHOUT CAUSE. If the Executive’s employment by the Company is terminated by the Company other than for Cause, the Company shall pay or provide the Executive with the following, subject to the provisions of Section 24 hereof:

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(i)the Accrued Benefits;

(ii)subject to the Executive’s not engaging in a Material Covenant Violation as defined hereinafter or any other breach of Section 10 hereof that is not cured within fifteen (15) days of written notice from the Board (a “Material Cooperation Violation”), the Executive shall be entitled to an amount equal to the following (the applicable amount determined below to be referred to herein as the “Severance Amount”):

an amount equal to one (1.0) multiplied by the sum of the Executive’s then current annual Base Salary and Target Bonus for the year of termination, paid in equal monthly installments for a period of twelve (12) months following such termination. Payments and benefits provided in this Section 7(c) shall be offset by Base Salary payments made during any notice period as defined in Section 2 where the Executive has been relieved of responsibilities; provided that the aggregate severance benefits payable shall be no less than as required by applicable law.

A “Material Covenant Violation” shall mean a breach of any of the restrictive covenants set forth in Section 10 hereof or in any other written agreement between the Executive and the Company and/or any of the Company’s or Parent’s direct or indirectly controlled subsidiaries (each an “Affiliate”) that causes material and demonstrable harm to the Company and/or any Affiliate.

(d)CHANGE IN CONTROL.

(i)This Section 7(d) shall apply if the Executive’s employment by the Com­pany is terminated (x) by the Company other than for Cause, or (y) by the Executive for good and valid reason as required by applicable law, in either case, during the two (2)-year period commencing upon a Change in Control. Subject to the Executive’s not engaging in a Material Covenant Violation or a Material Cooperation Violation, upon a termination described in the preceding sentence, the Executive shall receive the benefits set forth in Section 7(c) hereof, except that (i) the Severance Amount shall be two (2.0) multiplied by the annual sum of the Executive’s Base Salary and Target Bonus in effect for the then-current year of termination, and (ii) in lieu of receiving the Severance Amount in installments as contemplated under Section 7(c)(ii) hereof, the Executive shall receive a lump sum payment equal to the Severance Amount on the date of such termination.

(ii)For purposes of this Agreement, the term “Change in Control” shall mean the consummation off the first transaction following the Effective Date, whether in a single transaction or in a series of related transactions, in which any individual, entity or group (within the meaning of Section 13(d)(3) or 14(d)(2) of the U.S. Securities Exchange Act of 1934, as amended) (A) acquires (whether by merger, consolidation, or transfer or issuance of equity interests or otherwise) equity interests of the Parent (or any surviving or resulting entity) representing more than fifty percent (50%) of the outstanding voting securities or economic value of the Parent (or any surviving or resulting entity), or (B) acquires assets constituting all or substantially all (more than eighty percent (80%)) of the assets of the Parent and its subsidiaries (as determined on a consolidated basis).

8.OTHER OBLIGATIONS. Upon any termination of the Executive’s employment with the Company and at any time before at the request of the Board, the Executive shall promptly

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resign from any other position as an officer, director or fiduciary of the Company, Parent and any Affiliate.

9.RELEASE; NO MITIGATION; NO SET-OFF. Any and all amounts payable and benefits or additional rights provided pursuant to this Agreement beyond the Accrued Benefits shall only be payable if the Executive signs and delivers to the Company a general release of claims in favor of the Company in substantially the form of Exhibit A attached hereto not earlier than 1 month and 1 day, but not later than 60 days after his employment has ended and does not revoke such General Release. In no event shall the Executive be obligated to seek other employment or take any other action by way of mitigation of the amounts payable to the Executive under any of the provisions of this Agreement, nor shall the amount of any payment hereunder be reduced by any compensation earned by the Executive as a result of employment by a subsequent employer. The Company’s obligations to pay the Executive amounts hereunder shall not be subject to set-off, counterclaim or recoupment of amounts owed by the Executive to the Company or any Affiliates.

10.RESTRICTIVE COVENANTS.

(a)CONFIDENTIALITY. As of the date of this Agreement and during the course of the Executive’s employment with the Company, the Executive will learn confidential information regarding the Company. The Executive agrees that the Executive shall not, directly or indirectly, use, make available, sell, disclose or otherwise communicate to any person, other than in the course of the Executive’s assigned duties and for the benefit of the Company, either during the period of the Executive’s employment or at any time thereafter, any business and technical information or trade secrets, nonpublic, proprietary or confidential information, knowledge or data relating to the Company or any Affiliate, or received from third parties subject to a duty on the Company’s or any Affiliates’ part to maintain the confidentiality of such information and to use it only for certain limited purposes, in each case which shall have been obtained by the Executive during the Executive’s employment by the Company. The foregoing shall not apply to information that (i) was known to the public prior to its disclosure to the Executive; (ii) becomes generally known to the public subsequent to disclosure to the Executive through no wrongful act of the Executive or any representative of the Executive; or (iii) the Executive is required to disclose by applicable law, regulation or legal process (provided that the Executive provides the Company with prior notice of the contemplated disclosure and cooperates with the Company at its expense in seeking a protective order or other appropriate protection of such information). The Executive shall keep the terms and conditions of this Agreement strictly confidential, and the Executive hereby agrees not to disclose the terms and conditions hereof to any person or entity, other than immediate family members, legal advisors or personal tax or financial advisors, or prospective future employers solely for the purpose of disclosing the limitations on the Executive’s conduct imposed by the provisions of this Section 10 who, in each case, shall be instructed by the Executive to keep such information confidential.

(b)NONCOMPETITION. The Executive acknowledges that the Executive performs services of a unique nature for the Company that are irreplaceable, and that the Executive’s performance of such services to a competing business will result in irreparable harm to the Company. Accordingly, during the Executive’s employment hereunder and for a period of twenty-four (24) months (this period referred to herein as the “Restricted Period”), the Executive agrees

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that the Executive will not, directly or indirectly, own, manage, operate, control, be employed by (whether as an employee, consultant, independent contractor or otherwise, and whether or not for compensation) or render services to any person, firm, corporation or other entity, in whatever form, engaged in competition with any material business of the Company or any Affiliate or in any other material business in which the Company or any Affiliate has taken material steps and has material plans, on or prior to the date or termination, to be engaged in on or after such date, in any locale of any country in which the Company or any Affiliate conducts business. Notwithstanding the foregoing, nothing herein shall prohibit the Executive from being a passive owner of not more than one percent (1%) of the equity securities of a publicly traded corporation engaged in a business that is in competition with the Company or any of its affiliates, so long as the Executive has no active participation in the business of such corporation.

(c)NONSOLICITATION; NONINTERFERENCE. During the Executive’s em­ployment with the Company and for the Restricted Period, the Executive agrees that the Executive shall not, except in the furtherance of the Executive’s duties hereunder, directly or indirectly, individually or on behalf of any other person, firm, corporation or other entity, (i) solicit, aid or induce any customer of the Company or an Affiliate to purchase goods or services then sold by the Company or any Affiliate from another person, firm, corporation or other entity or assist or aid any other persons or entity in identifying or soliciting any such customer, (ii) solicit, aid or induce any employee, representative or agent of the Company or any Affiliate to leave such employment or retention or, in the case of employees, to accept employment with or render services to or with any other person, firm, corporation or other entity unaffiliated with the Company or any Affiliate, or hire or retain any such employee, or take any action to materially assist or aid any other person, firm, corporation or other entity in identifying, hiring or soliciting any such employee, or (iii) interfere, or aid or induce any other person or entity in interfering, with the relationship between the Company or any Affiliate and any of their respective vendors, joint ventures or licensors. An employee, representative or agent shall be deemed covered by this Section 10(c) while so employed or retained and for a period of six (6) months thereafter. Notwithstanding the foregoing, the provisions of this Section 10(c) shall not be violated by general advertising or solicitation not specifically targeted at Company or Affiliate-related individuals or entities.

(d)INTELLECTUAL PROPERTY RIGHTS. (i) The rights to inventions and de­signs made or conceived by the Executive individually or jointly while performing his employment activity and in performance of his contractual duties belong to the Company regardless of whether they are legally protected.

(ii)The rights to inventions and designs, made or conceived by the Executive while performing his employment activity, but not during the performance of his contractual duties, shall be assigned by the Executive to the Company as of their inception, regardless of whether they are legally protected. The Executive is obliged to inform the Company in writing of any such inventions or designs. The Company is entitled to grant the rights to these inventions and designs to the Executive. Should the Company retain such rights the Executive will be enti­tled to a special reasonable compensation.

(iii)Other rights to any work products and any know-how, which the Execu­tive creates or in which creation he participates while performing his employment activity belong exclusively to the Company. To the extent that work products (e.g., software, reports, documen­

8

tations) are protected by copyrights, the Executive hereby assigns to the Company any and all rights related to such work products, particularly the copyright and any and all rights of use, in­cluding the rights of production and duplication, of publishing, to use, to license or to sell, to distribute over data or online media, to modify and develop further as well to develop new products on the basis of the work product of the Executive or on the basis of parts of such work product.

(e)RETURN OF COMPANY PROPERTY. On the date of the Executive’s termina­tion of employment with the Company for any reason (or at any time prior thereto at the Company’s request), the Executive shall return all property belonging to the Company or any Af­filiate (including, but not limited to, any Company-provided laptops, computers, cell phones, wireless electronic mail devices or other equipment, or documents and property belonging to the Company). Any retention right is excluded.

(f)REASONABLENESS OF COVENANTS. In signing this Agreement, the Execu­tive gives the Company assurance that the Executive has carefully read and considered all of the terms and conditions of this Agreement, including the restraints imposed under this Section 10. The Executive agrees that these restraints are necessary for the reasonable and proper protection of the Company and the Company and any Affiliate’s trade secrets and confidential information and that each and every one of the restraints is reasonable in respect to subject matter, length of time and geographic area, and that these restraints, individually or in the aggregate, will not pre­vent the Executive from obtaining other suitable employment during the period in which the Executive is bound by the restraints. The Executive acknowledges that each of these covenants has a unique, very substantial and immeasurable value to the Company and its Affiliates and that the Executive has sufficient assets and skills to provide a livelihood while such covenants remain in force. It is also agreed that the Affiliates will have the right to enforce all of the Executive’s obligations to such Affiliates under this Agreement, including without limitation pursuant to this Section 10.

(g)REFORMATION. If it is determined by the competent court that any restriction in this Section 10 is excessive in duration or scope or is unreasonable or unenforceable under applicable law, it is the intention of the parties that such restriction may be modified or amended by the court to render it enforceable to the maximum extent permitted by Dutch law.

(h)SURVIVAL OF PROVISIONS. The obligations contained in Sections 10 and 11 hereof shall survive the termination or expiration of the Employment Term and the Executive’s employment with the Company and shall be fully enforceable thereafter.

11.COOPERATION. Upon the receipt of reasonable notice from the Company (including through outside counsel), the Executive agrees that while employed by the Company and thereafter (to the extent it does not materially interfere with the Executive’s employment or other business activities after employment by the Company), the Executive will respond and provide information with regard to matters in which the Executive has knowledge as a result of the Executive’s employment with the Company, and will provide reasonable assistance to the Company, the Affiliates and their respective representatives in defense of all claims that may be made against the Company or the Affiliates, and will assist the Company and the Affiliates in the prosecution of all claims that may be made by the Company or the Affiliates, to the extent that such claims may relate to the period of the Executive’s employment with the Company. The

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Executive also agrees to promptly inform the Board (to the extent that the Executive is legally permitted to do so) if the Executive is asked to assist in any investigation of the Company or the Affiliates (or their actions), regardless of whether a lawsuit or other proceeding has then been filed against the Company or Affiliates with respect to such investigation, and shall not do so unless legally required. Upon presentation of appropriate documentation, the Company shall pay or reimburse the Executive for all reasonable out-of-pocket travel, duplicating, telephonic, counsel and other expenses incurred by the Executive in complying with this Section 11.

12.EQUITABLE RELIEF AND OTHER REMEDIES. The Executive acknowl­edges and agrees that the Company’s remedies at law for a breach or threatened breach of any of the provisions of Section 10 hereof or Section 11 hereof would be inadequate and, in recognition of this fact, the Executive agrees that, in the event of such a breach or threatened breach, in addition to any remedies at law, the Company shall be entitled to obtain equitable relief in the form of specific performance, a temporary restraining order, a temporary or permanent injunction or any other equitable remedy which may then be available. In the event of a Material Covenant Violation or a Material Cooperation Violation by the Executive, any severance being paid to the Executive pursuant to this Agreement or otherwise shall immediately cease unless otherwise prohibited by applicable law. In case of a breach by the Executive of any of the covenants contained in Section 10 or Section 11 hereof (i) any Severance Amount payable by the Company, if any, shall be forfeited and (ii) the Executive shall pay to the Company a contractual penalty in an amount equal to (i) the Executive's last annual Base Salary for each individual breach of Sections 10(a), 10(b) and 10(c)(i), (ii) one twelfth (1/12^th) of the Executive’s last annual Base salary for each individual breach of Sections 10(c)(ii), 10(c)(iii) and 11 and EUR 10,000 for each individual breach of Sections 10(e). In addition, the Executive shall have to compensate the Company for any damages and financial losses directly arising out of or relating to such breach. The Executive cannot disburden himself from the aforementioned prohibitions by the payment of the contractual penalty and/or damages.

13.NO ASSIGNMENTS. This Agreement is personal to each of the parties hereto. Except as provided in this Section 13 hereof, no party may assign or delegate any rights or obligations hereunder without first obtaining the written consent of the other party hereto. The Company shall assign this Agreement to any successor to all or substantially all of the business and/or assets of the Company or Parent, provided that the Company shall require such successor to expressly assume and agree to perform this Agreement in the same manner and to the same extent that the Company would be required to perform it if no such succession had taken place, and provided that the Company agrees to perform such obligations if such successor fails to do so in a timely manner. As used in this Agreement, “Company” shall mean the Company and any successor to all or substantially all of its business and/or assets, which assumes and agrees to perform the duties and obligations of the Company under this Agreement by operation of law or otherwise.

14.NOTICES. For purposes of this Agreement, notices and all other communications provided for in this Agreement shall be in writing and shall be deemed to have been duly given (a) on the date of delivery, if delivered by hand, (b) on the date of transmission, if delivered by confirmed facsimile or electronic mail, (c) on the first business day following the date of deposit, if delivered by guaranteed overnight delivery service, or (d) on the fourth business day following

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the date delivered or mailed with a national postal carrier by registered or certified mail, return receipt requested, postage prepaid, addressed as follows:

If to the Executive:

At the address (or to the facsimile number) shown
in the books and records of the Company.

If to the Company:

Trinseo Netherlands B.V.

c/o Trinseo LLC

Chief Legal Officer

1000 Chesterbrook Boulevard, Suite 300

Berwyn, Pennsylvania 19312

And

With a copy (which shall not constitute notice hereunder) to:

Trinseo Netherlands B.V.

Human Resources Manager

Postbox 48

4530AA Terneuzen, Netherlands

or to such other address as either party may have furnished to the other in writing in accordance herewith, except that notices of change of address shall be effective only upon receipt.

15.SECTION HEADINGS; INCONSISTENCY. The section headings used in this Agreement are included solely for convenience and shall not affect, or be used in connection with, the interpretation of this Agreement. In the event of any inconsistency between the terms of this Agreement (including the Exhibits hereto) and any form, award, plan or policy of the Company, the terms of this Agreement shall govern and control.

16.SEVERABILITY. The provisions of this Agreement shall be deemed severable and the invalidity or unenforceability of any provision shall not affect the validity or enforceability of the other provisions hereof which shall be replace by such valid and enforceable provision that best reflects the Parties original intent.

17.SUPREMECY & COUNTERPARTS. This Agreement supersedes and replaces all prior agreements and understandings, whether oral or written, in connection with the subject matter hereof.  This Agreement may be executed in several counterparts, each of which shall be deemed to be an original but all of which together will constitute one and the same instrument.

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18.INDEMNIFICATION. The Company hereby agrees to indemnify the Executive and hold the Executive harmless to the fullest extent allowable under applicable law against and in respect of any and all actions, suits, proceedings, claims, demands, judgments, costs, expenses (including attorney’s fees, and the advancement of such fees subject to any legally required re­payment undertaking), losses, and damages resulting from the Executive’s performance of the Executive’s duties and obligations with the Company. This obligation shall survive the termination of the Executive’s employment with the Company.

19.LIABILITY INSURANCE. The Company shall cover the Executive under direc­tors’ and officers’ liability insurance both during and, while potential liability exists, after the Employment Term in the same amount and to the same extent as the Company covers its other officers and directors.

20.GOVERNING LAW. This Agreement, the rights and obligations of the parties hereto, and any claims or disputes relating thereto, shall exclusively be governed by and construed in accordance with the substantive laws of The Netherlands.

21.DISPUTE RESOLUTION. Each of the parties agrees that any dispute between the parties shall be resolved only in the courts of The Netherlands, in accordance with The Netherlands Code of Civil Procedure.

22.MISCELLANEOUS. No provision of this Agreement may be modified, waived or discharged unless such waiver, modification or discharge is agreed to in writing and signed by the Executive and such officer or director as may be designated by the Board. No waiver by either party hereto at any time of any breach by the other party hereto of, or compliance with, any condition or provision of this Agreement to be performed by such other party shall be deemed a waiver of similar or dissimilar provisions or conditions at the same or at any prior or subsequent time. This Agreement together with all exhibits hereto sets forth the entire agreement of the parties hereto in respect of the subject matter contained herein and supersedes any and all prior agreements or understandings between the Executive and the Company with respect to the subject matter hereof, whether written or oral. No agreements or representations, oral or otherwise, express or implied, with respect to the subject matter hereof have been made by either party which are not expressly set forth in this Agreement.

23.REPRESENTATIONS; ACTIONS BY PRIOR EMPLOYERS. The Executive represents and warrants to the Company that (a) the Executive has used the Executive’s best efforts to provide the Company with (i) each agreement with a predecessor employer which may have any bearing on the Executive’s legal right to enter into this Agreement and to perform all of the obligations on the Executive’s part to be performed hereunder in accordance with its terms, or (ii) a summary of the applicable provisions of each such agreement which the Executive may not provide to the Company due to an existing confidentiality obligation, and (b) other than the agreements referenced in the preceding clause (a), the Executive is not a party to any agreement or understanding, whether written or oral, and is not subject to any restriction (including, without limitation, any non-competition restriction from a prior employer), which, in either case, could prevent the Executive from entering into this Agreement or performing all of the Executive’s duties and obligations hereunder. The Executive understands that the foregoing representations are a material inducement to the Company entering into this Agreement, and to the extent that either

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of such representations is untrue in any material respect at any time or for any reason, this Agreement shall be voidable by the Company such that the parties hereunder shall be relieved of all of their respective duties and obligations hereunder; provided that any termination of the Ex­ecutive’s employment resulting from the Company exercising its rights pursuant to this sentence shall have the same consequences, especially financial consequences, as a termination of em­ployment by the Executive without good and valid reason as required by applicable law. If any prior employer of the Executive, or any affiliate of any such prior employer, challenges the Executive’s right to enter into this Agreement and to perform all of the Executive’s obligations hereunder (whether by action against the Executive, the Company, Parent and/or an Affiliate), the Company (on behalf of itself, Parent and all Affiliates) and the Executive each agree to use their reasonable best efforts to defend against such challenge.

24.WITHHOLDING. The Company will deduct from the Employee's gross re­muneration as provided for in this Agreement the applicable Employee contributions, respectively premiums to any applicable social security schemes, and any premiums for the pension fund, as well as applicable taxes, if any in accordance with the respective laws, regulations and plan documents.

25.FURTHER ASSURANCES. The parties hereto shall cooperate with each other and do, or procure the doing of, all acts and things, and execute, or procure the execution of, all documents, as may reasonably be required to give full effect to this Agreement.

26.UNILATERAL AMENDMENT.  In accordance with article 7:613 Netherlands Civil Code, the Company reserves the right to amend this Agreement unilaterally under the condition that the Company’s interests in introducing the amendment concerned are so significant that, in accordance with the principles of reasonableness and fairness, they must take precedence over any interests of the Executive that could be harmed by this amendment.

[REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

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IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the date first written above.

Trinseo Netherlands B.V.	Executive
Signature #1:  /s/ Jos van den Brink	Signature:  /s/ Han Hendriks
Name:  Jos van den Brink	Name:  Han Hendriks
Title:  Director
Date:  5 Aug 2022	Date:  28 July 2022
Signature #2:  /s/ Louis Oostvogels
Name:  Louis Oostvogels
Title:  Director
Date:  5 Aug 2022

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Employment Agreement Signature Page

EXHIBIT A

GENERAL RELEASE

I, CANDIDATE NAME, in consideration of and subject to the performance by Trinseo Netherlands B.V.. (together with its Affiliates, the “Company”), of its obligations under the Employment Agreement, dated as of [●] (the “Agreement”), do hereby release and forever discharge as of the date hereof the Company and its respective Affiliates and all present, former and future directors, officers, employees, successors and assigns of the Company and its Affiliates and direct or indirect owners (collectively, the “Released Parties”) to the extent provided below. The Released Parties are intended third-party beneficiaries of this General Release, and this General Release may be enforced by each of them in accordance with the terms hereof in respect of the rights granted to such Released Parties hereunder. Terms used herein but not otherwise defined shall have the meanings given to them in the Agreement.

1.I understand that any payments or benefits paid or granted to me under Section 7 of the Agreement represent, in part, consideration for signing this General Release and are not salary, wages or benefits to which I was already entitled. I understand and agree that I will not receive certain of the payments and benefits specified in Section 7 of the Agreement. Such payments and benefits will not be considered compensation for purposes of any employee benefit plan, program, policy or arrangement maintained or hereafter established by the Company or its affiliates.

2.Except as provided in paragraphs 1 above and 5 below and except for the provisions of the Agreement which expressly survive the termination of my employment with the Company, I knowingly and voluntarily (for myself, my heirs, executors, administrators and assigns) release and forever discharge the Company and the other Released Parties from any and all claims, suits, controversies, actions, causes of action, cross-claims, counter-claims, demands, debts, compensatory damages, liquidated damages, pu­nitive or exemplary damages, other damages, claims for costs and attorneys’ fees, or liabilities of any nature whatsoever in law and in equity, both past and present (through the date this General Release becomes effective and enforceable) and whether known or unknown, suspected, or claimed against the Company or any of the Released Parties which I, my spouse, or any of my heirs, executors, administrators or assigns, may have, which arise out of or are connected with my employment with, or my separation or termination from, the Company (all of the foregoing collectively referred to herein as the “Claims”).

3.I represent that I have made no assignment or transfer of any right, claim, demand, cause of action, or other matter covered by paragraph 2 above.

4.I agree that this General Release does not waive or release any rights or claims that I may have which arise after the date I execute this General Release. I acknowledge and agree that my separation from employment with the Company in compliance with the terms of the Agreement shall not serve as the basis for any claim or action.

5.I agree that I hereby waive all rights to sue or obtain equitable, remedial or punitive relief from any or all Released Parties of any kind whatsoever in respect of any Claim, including, without limitation, reinstatement, back pay, front pay, and any form of injunctive relief. Notwithstanding

A-1

the above, I further acknowledge that I am not waiving and am not being required to waive any right that cannot be waived under law at the time I sign this General Release, including the right to file an administrative charge or participate in an administrative investigation or proceeding; provided, however, that I disclaim and waive any right to share or participate in any monetary award resulting from the prosecution of such charge or investigation or proceeding. Additionally, I am not waiving any right to the Accrued Benefits or indemnity.

6.In signing this General Release, I acknowledge and intend that it shall be effective as a bar to each and every one of the Claims hereinabove mentioned or implied. I expressly consent that this General Release shall be given full force and effect according to each and all of its express terms and provisions, including those relating to unknown and unsuspected Claims (not­withstanding any state or local statute that expressly limits the effectiveness of a general release of unknown, unsuspected and unanticipated Claims), if any, as well as those relating to any other Claims hereinabove mentioned or implied. I acknowledge and agree that this waiver is an essential and material term of this General Release and that without such waiver the Company would not have agreed to the terms of the Agreement. I further agree that in the event I should bring a Claim seeking damages against the Company, or in the event I should seek to recover against the Company in any Claim brought by a governmental agency on my behalf, this General Release shall serve as a complete defense to such Claims to the maximum extent permitted by law. I further agree that I am not aware of any pending claim of the type described in paragraph 2 above as of the execution of this General Release.

7.I agree that neither this General Release, nor the furnishing of the consideration for this General Release, shall be deemed or construed at any time to be an admission by the Company, any Released Party or myself of any improper or unlawful conduct.

8.I agree that if I violate this General Release by suing the Company or the other Released Parties, I will pay all costs and expenses of defending against the suit incurred by the Released Parties, including reasonable attorneys’ fees.

9.I agree that this General Release and the Agreement are confidential and agree not to dis­close any information regarding the terms of this General Release or the Agreement, except to my immediate family and any tax, legal or other counsel I have consulted regarding the meaning or effect hereof or as required by law, and I will instruct each of the foregoing not to disclose the same to anyone. The Company agrees to disclose any such information only to any tax, legal or other counsel of the Company as required by law.

10.Any non-disclosure provision in this General Release does not prohibit or restrict me (or my attorney) from responding to any inquiry about this General Release or its underlying facts and circumstances by the Securities and Exchange Commission (SEC), the Financial Industry Regulatory Authority (FINRA), any other self-regulatory organization or any governmental entity.

11.I represent that I am not aware of any claim by me other than the claims that are released by this General Release. I acknowledge that I may hereafter discover claims or facts in addition to or different than those which I now know or believe to exist with respect to the subject matter of the release set forth in paragraph 2 above and which, if known or suspected at the time of entering

A-2

into this General Release, may have materially affected this General Release and my decision to enter into it.

12.Notwithstanding anything in this General Release to the contrary, this General Release shall not relinquish, diminish, or in any way affect any rights or claims arising out of any breach by the Company or by any Released Party of the Agreement after the date hereof.

13.Whenever possible, each provision of this General Release shall be interpreted in, such manner as to be effective and valid under applicable law, but if any provision of this General Release is held to be invalid, illegal or unenforceable in any respect under any applicable law or rule in any jurisdiction, such invalidity, illegality or unenforceability shall not affect any other provision or any other jurisdiction, but this General Release shall be reformed, construed and enforced in such jurisdiction as if such invalid, illegal or unenforceable provision had never been contained herein and if possible under applicable law, replaced by such valid, legal and enforceable provision that best reflects the intent of the invalid, illegal or unenforceable provision.

14.This General release is subject to the substantive laws of The Netherlands.

BY SIGNING THIS GENERAL RELEASE, I REPRESENT AND AGREE THAT:

1. I HAVE READ IT CAREFULLY;

2. I UNDERSTAND ALL OF ITS TERMS AND KNOW THAT I AM GIVING UP IMPORTANT RIGHTS;

3. I VOLUNTARILY CONSENT TO EVERYTHING IN IT;

4. I HAVE SIGNED THIS GENERAL RELEASE KNOWINGLY AND VOLUN­TARILY; AND

5. I AGREE THAT THE PROVISIONS OF THIS GENERAL RELEASE MAY NOT BE AMENDED, WAIVED, CHANGED OR MODIFIED EXCEPT BY AN INSTRUMENT IN WRITING SIGNED BY AN AUTHORIZED REPRE­SENTATIVE OF THE COMPANY AND BY ME.

SIGNED:​ ​​ ​​ ​​ ​​ ​​ ​DATED:​ ​​ ​​ ​​ ​

A-3

EX-31.1

Exhibit 31.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER

I, Frank Bozich, certify that:

1. I have reviewed this quarterly report on Form 10-Q of Trinseo PLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal controls over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: May 9, 2024

By:	/s/ Frank Bozich
Name:	Frank Bozich
Title:	Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATION OF CHIEF FINANCIAL OFFICER

I, David Stasse, certify that:

1. I have reviewed this quarterly report on Form 10-Q of Trinseo PLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal controls over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: May 9, 2024

J.
	By:	/s/ David Stasse
	Name:	David Stasse
	Title:	Chief Financial Officer

EX-32.1

Exhibit 32.1

Certification of CEO Pursuant to 18 U.S.C. Section 1350,

As Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the quarterly report of Trinseo PLC (the “Company”) on Form 10-Q for the period ended March 31, 2024 (the “Report”), as filed with the Securities and Exchange Commission on the date hereof, I, the undersigned, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, to the best of my knowledge, that:

(1) The Report fully complies with the requirements of Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: May 9, 2024

By:	/s/ Frank Bozich
Name:	Frank Bozich
Title:	Chief Executive Officer

EX-32.2

Exhibit 32.2

Certification of CFO Pursuant to 18 U.S.C. Section 1350,

As Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the quarterly report of Trinseo PLC (the “Company”) on Form 10-Q for the period ended March 31, 2024 (the “Report”), as filed with the Securities and Exchange Commission on the date hereof, I, the undersigned, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, to the best of my knowledge, that:

(1) The Report fully complies with the requirements of Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: May 9, 2024

J.
	By:	/s/ David Stasse
	Name:	David Stasse
	Title:	Chief Financial Officer

XML

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 03, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-36473
Entity Registrant Name	Trinseo PLC
Entity Incorporation, State or Country Code	L2
Entity Tax Identification Number	00-0000000
Entity Address, Address Line One	440 East Swedesford Road
Entity Address, Address Line Two	Suite 301
Entity Address, City or Town	Wayne
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19087
City Area Code	610
Local Phone Number	240-3200
Title of 12(b) Security	Ordinary Shares, par value $0.01 per share
Trading Symbol	TSE
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		35,294,231
Entity Central Index Key	0001519061
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Amendment Flag	false

XML

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 166.4	$ 259.1
Accounts receivable, net of allowance for doubtful accounts (March 31, 2024: $6.6; December 31, 2023: $6.7)	556.5	490.8
Inventories	431.2	404.7
Other current assets	42.6	39.5
Total current assets	1,196.7	1,194.1
Investments in unconsolidated affiliate	258.4	252.2
Property, plant and equipment, net of accumulated depreciation (March 31, 2024: $775.9; December 31, 2023: $778.2)	624.2	643.7
Other assets
Goodwill	62.3	63.8
Other intangible assets, net	668.3	693.9
Right-of-use assets - operating, net	60.7	65.3
Deferred income tax assets	46.6	44.3
Deferred charges and other assets	72.2	71.9
Total other assets	910.1	939.2
Total assets	2,989.4	3,029.2
Current liabilities
Short-term borrowings and current portion of long-term debt	21.1	20.9
Accounts payable	478.9	449.7
Current lease liabilities - operating	15.5	16.3
Income taxes payable	13.8	10.9
Accrued expenses and other current liabilities	202.7	174.8
Total current liabilities	732.0	672.6
Noncurrent liabilities
Long-term debt, net of unamortized deferred financing fees	2,276.7	2,277.6
Noncurrent lease liabilities - operating	47.5	51.7
Deferred income tax liabilities	41.2	43.5
Other noncurrent obligations	240.0	251.8
Total noncurrent liabilities	2,605.4	2,624.6
Commitments and contingencies (Note 13)
Shareholders' equity
Ordinary shares, $0.01 nominal value, 4,000.0 shares authorized (March 31, 2024: 39.4 shares issued and 35.3 shares outstanding; December 31, 2023: 39.4 shares issued and 35.2 shares outstanding)	0.4	0.4
Preferred shares, €0.01 nominal value, 1,000.0 shares authorized (no shares issued or outstanding)
Additional paid-in-capital	507.8	504.2
Treasury shares, at cost (March 31, 2024: 4.1 shares; December 31, 2023: 4.1 shares)	(200.0)	(200.0)
Accumulated deficit	(518.8)	(443.0)
Accumulated other comprehensive loss	(137.4)	(129.6)
Total shareholders' equity	(348.0)	(268.0)
Total liabilities and shareholders' equity	$ 2,989.4	$ 3,029.2

XML

Condensed Consolidated Balance Sheets (Parenthetical) shares in Thousands, $ in Millions	Mar. 31, 2024 USD ($) $ / shares shares	Mar. 31, 2024 € / shares	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2023 € / shares
Allowance for doubtful accounts | $	$ 6.6		$ 6.7
Ordinary shares, nominal value | $ / shares	$ 0.01		$ 0.01
Ordinary shares, shares authorized	4,000,000		4,000,000
Ordinary shares, shares issued	39,400		39,400
Ordinary shares, shares outstanding	35,300		35,200
Treasury stock, shares	4,100		4,100
Preferred stock, par value | € / shares		€ 0.01		€ 0.01
Preferred stock, shares authorized	1,000,000		1,000,000
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Accumulated depreciation | $	$ 775.9		$ 778.2
Deferred Ordinary Shares
Ordinary shares, nominal value | € / shares		€ 1.00		€ 1.00
Ordinary shares, shares authorized	25		25
Ordinary shares, shares issued	25		25
Ordinary shares, shares outstanding	25		25

XML

Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Consolidated Statements of Operations
Net sales	$ 904.0	$ 996.3
Cost of sales	843.4	959.1
Gross profit	60.6	37.2
Selling, general and administrative expenses	70.1	84.7
Equity in earnings of unconsolidated affiliate	6.2	17.6
Impairment and other charges		0.3
Operating loss	(3.3)	(30.2)
Interest expense, net	63.0	38.3
Other expense (income), net	3.8	(2.9)
Loss before income taxes	(70.1)	(65.6)
Provision for (benefit from) income taxes	5.4	(16.7)
Net loss	$ (75.5)	$ (48.9)
EARNINGS PER SHARE
Weighted average shares-basic	35.3	35.0
Net loss per share-basic	$ (2.14)	$ (1.40)
Weighted average shares-diluted	35.3	35.0
Net loss per share-diluted:	$ (2.14)	$ (1.40)

XML

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Consolidated Statements of Comprehensive Income (Loss)
Net Income (Loss)	$ (75.5)	$ (48.9)
Other comprehensive income (loss), net of tax:
Cumulative translation adjustments (net of tax of $0.0 and $0.0)	(11.8)	10.5
Net gain (loss) on cash flow hedges (net of tax of $(1.7) and $(2.5))	4.4	(7.4)
Amounts reclassified from accumulated other comprehensive income (loss)	(0.4)	0.3
Total other comprehensive income (loss), net of tax	(7.8)	3.4
Comprehensive loss	$ (83.3)	$ (45.5)

XML

Condensed Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Consolidated Statements of Comprehensive Income (Loss)
Cumulative translation adjustments, tax	$ 0.0	$ 0.0
Net gain (loss) on cash flow hedges, tax	$ (1.7)	$ (2.5)

XML

Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Common Stock	Additional Paid-In Capital	Treasury Shares	Accumulated Other Comprehensive Income	Retained Earnings (Accumulated Deficit)	Total
Balance at beginning of period at Dec. 31, 2022	$ 0.4	$ 486.7	$ (200.0)	$ (131.3)	$ 264.5	$ 420.3
Balance at beginning of period, shares at Dec. 31, 2022	35.1
Balance at beginning of period, Treasury shares at Dec. 31, 2022			4.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)					(48.9)	(48.9)
Other comprehensive loss				3.4		3.4
Share-based compensation activity		6.6				6.6
Share-based compensation activity, shares	0.1
Dividends on ordinary shares					(5.2)	(5.2)
Balance at end of period at Mar. 31, 2023	$ 0.4	493.3	$ (200.0)	(127.9)	210.4	376.2
Balance at end of period, shares at Mar. 31, 2023	35.2
Balance at end of period, Treasury shares at Mar. 31, 2023			4.1
Balance at beginning of period at Dec. 31, 2023	$ 0.4	504.2	$ (200.0)	(129.6)	(443.0)	$ (268.0)
Balance at beginning of period, shares at Dec. 31, 2023	35.2					35.2
Balance at beginning of period, Treasury shares at Dec. 31, 2023			4.1			4.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)					(75.5)	$ (75.5)
Other comprehensive loss				(7.8)		(7.8)
Share-based compensation activity		3.6				3.6
Share-based compensation activity, shares	0.1
Dividends on ordinary shares					(0.3)	(0.3)
Balance at end of period at Mar. 31, 2024	$ 0.4	$ 507.8	$ (200.0)	$ (137.4)	$ (518.8)	$ (348.0)
Balance at end of period, shares at Mar. 31, 2024	35.3					35.3
Balance at end of period, Treasury shares at Mar. 31, 2024			4.1			4.1

XML

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Consolidated Statements of Shareholders' Equity
Dividends on ordinary shares	$ 0.01	$ 0.14

XML

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net loss	$ (75.5)	$ (48.9)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Depreciation and amortization	45.0	56.0
Amortization of deferred financing fees and issuance discount	3.7	2.3
Deferred income tax benefit	(3.8)	(16.6)
Share-based compensation expense	5.9	8.2
Earnings of unconsolidated affiliate, net of dividends	(6.2)	2.4
Unrealized net (gain) loss on foreign exchange forward contracts	(5.0)	1.5
Unrealized net loss on commodity economic swap contracts	2.4	5.8
Gain on sale of other assets	(3.6)
Impairment charges or write-offs		0.3
Changes in assets and liabilities
Accounts receivable	(72.6)	(29.2)
Inventories	(31.2)	55.1
Accounts payable and other current liabilities	80.3	26.5
Income taxes payable	2.9	(7.0)
Other assets, net	6.3	3.8
Other liabilities, net	(14.8)	(14.8)
Cash provided by (used in) operating activities	(66.2)	45.4
Cash flows from investing activities
Capital expenditures	(15.7)	(21.8)
Proceeds from the sale of other assets	4.7
Cash used in investing activities	(11.0)	(21.8)
Cash flows from financing activities
Deferred financing fees	0.4
Short-term borrowings, net	(3.7)	(2.7)
Dividends paid	(0.6)	(11.8)
Proceeds from exercise of option awards		0.1
Withholding taxes paid on restricted share units		(1.3)
Acquisition-related contingent consideration payment	(0.7)	(1.2)
Repurchases and repayments of long-term debt	(4.6)	(3.6)
Proceeds from Accounts Receivable Securitization Facility	30.0
Repayments of Accounts Receivable Securitization Facility	(30.0)
Cash used in financing activities	(9.2)	(20.5)
Effect of exchange rates on cash	(3.2)	2.3
Net change in cash, cash equivalents, and restricted cash	(89.6)	5.4
Cash, cash equivalents, and restricted cash-beginning of period	261.1	211.7
Cash, cash equivalents, and restricted cash-end of period	171.5	217.1
Less: Restricted cash	5.1
Cash and cash equivalents-end of period	$ 166.4	$ 217.1

XML

BASIS OF PRESENTATION

3 Months Ended

Mar. 31, 2024

BASIS OF PRESENTATION

BASIS OF PRESENTATION

NOTE 1—BASIS OF PRESENTATION

The unaudited interim condensed consolidated financial statements of Trinseo PLC and its subsidiaries (the “Company”) as of and for the periods ended March 31, 2024 and 2023 were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and reflect all adjustments, consisting only of normal recurring adjustments, which, in the opinion of management, are considered necessary for the fair statement of the results for the periods presented. Because they cover interim periods, the statements and related notes to the financial statements do not include all disclosures normally provided in annual financial statements, and therefore, these statements should be read in conjunction with the 2023 audited consolidated financial statements included within the Company’s Annual Report on Form 10-K (“Annual Report”) filed with the Securities and Exchange Commission (“SEC”) on February 23, 2024. The Company’s condensed consolidated financial statements presented herein reflect the latest estimates and assumptions made by management that affect the reported amounts and related disclosures as of and for the period ended March 31, 2024. However, actual results could differ from these estimates and assumptions.

The December 31, 2023 condensed consolidated balance sheet data presented herein was derived from the Company’s December 31, 2023 audited consolidated financial statements, but does not include all disclosures required by GAAP for annual periods.

Effective January 1, 2024, the Company’s Feedstocks segment, which included the Company’s production and procurement of styrene monomer outside of North America, was eliminated as a result of the closures of the styrene plants located in Boehlen, Germany and Terneuzen, the Netherlands under an asset restructuring plan. As a result, the Company realigned its reporting segments to reflect the new model under which the business is managed with five segments, all of which remain unchanged from the Company’s prior six segment segmentation: Engineered Materials, Latex Binders, Plastics Solutions, Polystyrene, and Americas Styrenics. Therefore, certain prior year information has been adjusted to show the historical results of the Feedstocks segment within the segments that consumed styrene monomer in their end products, Latex Binders, Plastics Solutions and Polystyrene. Refer to Notes 3, 4 and 16 for further information. Throughout this Quarterly Report, unless otherwise indicated, amounts and activity are presented on a continuing operations basis.

XML

RECENT ACCOUNTING GUIDANCE

3 Months Ended

Mar. 31, 2024

RECENT ACCOUNTING GUIDANCE

RECENT ACCOUNTING GUIDANCE

NOTE 2—RECENT ACCOUNTING GUIDANCE

As of March 31, 2024, there was no recently issued accounting standards which would have a material effect on the Company’s condensed consolidated financial statements.

XML

INCOME TAXES

3 Months Ended

Mar. 31, 2024

INCOME TAXES

INCOME TAXES

NOTE 5—INCOME TAXES

	Three Months Ended
	March 31,
	2024			2023
Effective income tax rate		(7.7)	%		25.4	%

Provision for income taxes for the three months ended March 31, 2024 totaled $5.4 million, resulting in an effective tax rate of (7.7)%. Benefit from income taxes for the three months ended March 31, 2023 totaled $16.7 million, resulting in an effective tax rate of 25.4%.

The most significant driver of the decrease in the effective income tax rate for the three months ended March 31, 2024 compared to the prior year was the increase in losses not anticipated to provide a tax benefit, due to the increase in valuation allowances primarily in the United States and Switzerland.

In determining the need for a valuation allowance, the Company weighs both positive and negative evidence in the various jurisdictions in which it operates to determine whether sufficient future taxable income will be generated to permit use of the existing deferred tax assets. Based on cumulative earnings in the Company’s China subsidiary during the prior three years, as well as other positive evidence, the Company believes it is more likely than not that the net deferred tax assets in the Company’s China subsidiary will be realized as of March 31, 2024. However, given the Company’s recent losses, the Company will continue to evaluate positive and negative evidence over the next 12 months, that could result in sufficient objective negative evidence for the Company to reach a conclusion that a partial or full valuation allowance against the net deferred tax assets will be needed. A partial or full valuation allowance would result in the material reduction of deferred tax assets and a corresponding increase to income tax expense in the period the valuation allowance is recorded. The exact timing and amount of the valuation allowance are subject to change on the basis of the losses sustained in China in the current year and forecasted future earnings, as well as other evidence. The Company’s China Subsidiary has $13.5 million of net deferred tax assets as of March 31, 2024.

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EARNINGS PER SHARE

3 Months Ended

Mar. 31, 2024

EARNINGS PER SHARE

EARNINGS PER SHARE

NOTE 6—EARNINGS PER SHARE

Basic earnings per ordinary share (“basic EPS”) is computed by dividing net income available to ordinary shareholders by the weighted average number of the Company’s ordinary shares outstanding for the applicable period. Diluted earnings per ordinary share (“diluted EPS”) is calculated using net income available to ordinary shareholders divided by diluted weighted average ordinary shares outstanding during each period, which includes unvested RSUs, option awards, and PSUs. Diluted EPS considers the impact of potentially dilutive securities except in periods in which there is a loss from continuing operations because the inclusion of the potential ordinary shares would have an anti-dilutive effect.

The following table presents basic EPS and diluted EPS for the three months ended March 31, 2024 and 2023.

	Three Months Ended
	March 31,
(in millions, except per share data)	2024		2023
Earnings:
Net loss	$	(75.5)	$	(48.9)
Shares:
Weighted average ordinary shares outstanding		35.3		35.0
Dilutive effect of RSUs, option awards, and PSUs(1)		—		—
Diluted weighted average ordinary shares outstanding		35.3		35.0
Loss per share:
Loss per share‒basic	$	(2.14)	$	(1.40)
Loss per share‒diluted	$	(2.14)	$	(1.40)

(1) Refer to Note 15 for discussion of RSUs, option awards, and PSUs granted to certain Company directors and employees. As the Company recorded a net loss from continuing operations for the three months ended March 31, 2024 and March 31, 2023, potential shares related to equity-based awards have been excluded from the calculation of diluted EPS, as doing so would be anti-dilutive.

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INVENTORIES

3 Months Ended

Mar. 31, 2024

INVENTORIES

INVENTORIES

NOTE 7—INVENTORIES

Inventories consisted of the following:

	March 31,		December 31,
	2024		2023
Finished goods	$	190.2	$	162.4
Raw materials and semi-finished goods		199.4		200.9
Supplies		41.6		41.4
Total	$	431.2	$	404.7

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INVESTMENTS IN UNCONSOLIDATED AFFILIATES

3 Months Ended

Mar. 31, 2024

INVESTMENTS IN UNCONSOLIDATED AFFILIATES

INVESTMENTS IN UNCONSOLIDATED AFFILIATES

NOTE 8—INVESTMENTS IN UNCONSOLIDATED AFFILIATES

The Company maintains an investment in an unconsolidated affiliate, Americas Styrenics LLC (“Americas Styrenics,” a styrene and polystyrene joint venture with Chevron Phillips Chemical Company LP), which is accounted for using the equity method. The results of Americas Styrenics are included within its separate reporting segment.

Americas Styrenics is a privately held company; therefore, a quoted market price for its equity interests is not available. The summarized financial information of the Company’s unconsolidated affiliate is shown below.

	Three Months Ended
	March 31,
	2024		2023
Sales	$	386.0	$	443.3
Gross profit	$	11.6	$	52.9
Net income (loss)	$	(3.7)	$	37.8

As of March 31, 2024 and December 31, 2023, the Company’s investment in Americas Styrenics was $258.4 million and $252.2 million, respectively, which was $12.6 million and $4.8 million greater than the Company’s 50% share of the underlying net assets of Americas Styrenics, respectively. This amount represents the difference between the book value of assets held by the joint venture and the Company’s 50% share of the total recorded value of the joint venture’s assets, inclusive of certain adjustments to conform with the Company’s accounting policies. This difference is being amortized over a weighted average remaining useful life of approximately 2.6 years as of March 31, 2024. The Company received dividends of $0.0 million and $20.0 million from Americas Styrenics during the three months ended March 31, 2024 and 2023, respectively.

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GOODWILL

3 Months Ended

Mar. 31, 2024

GOODWILL

GOODWILL

NOTE 9—GOODWILL

The following table shows changes in the carrying amount of goodwill, by segment, from December 31, 2023 to March 31, 2024:

	Engineered		Latex		Plastics				Americas
	Materials		Binders		Solutions		Polystyrene		Styrenics		Total
Balance at December 31, 2023	$	—	$	15.4	$	44.0	$	4.4	$	—	$	63.8
Foreign currency impact		—		(0.4)		(1.0)		(0.1)		—		(1.5)
Balance at March 31, 2024	$	—	$	15.0	$	43.0	$	4.3	$	—	$	62.3

As of March 31, 2024 and December 31, 2023, the reported balance of goodwill included accumulated impairment losses of $646.1 million in the Engineered Materials segment.

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LONG TERM DEBT & AVAILABLE FACILITIES

3 Months Ended

Mar. 31, 2024

LONG TERM DEBT & AVAILABLE FACILITIES

LONG TERM DEBT & AVAILABLE FACILITIES

NOTE 10—LONG TERM DEBT & AVAILABLE FACILITIES

Refer to the Annual Report for definitions of capitalized terms not included herein and further background on the Company’s debt structure discussed below. The Company was in compliance with all debt related covenants as of March 31, 2024 and December 31, 2023.

As of March 31, 2024 and December 31, 2023, debt consisted of the following:

			March 31, 2024						December 31, 2023
	Interest Rate as of March 31, 2024	Maturity Date	Carrying Amount		Unamortized Deferred Financing Fees (1)		Total Debt, Less Unamortized Deferred Financing Fees		Carrying Amount		Unamortized Deferred Financing Fees (1)		Total Debt, Less Unamortized Deferred Financing Fees
2029 Senior Notes	5.125%	April 2029	$	447.0	$	(10.7)	$	436.3	$	447.0	$	(11.1)	$	435.9
2025 Senior Notes (2)	5.375%	September 2025		115.0		(0.5)		114.5		115.0		(0.6)		114.4
Senior Credit Facility
2028 Term Loan B	8.105%	May 2028		727.2		(11.2)		716.0		728.9		(11.8)		717.1
2026 Revolving Facility (3)	Various	May 2026		—		—		—		—		—		—
2028 Refinance Term Loans (2)	13.823%	May 2028		1,045.2		(21.2)		1,024.0		1,046.5		(22.6)		1,023.9
Accounts Receivable Securitization Facility (4)	Various	November 2025		—		—		—		—		—		—
Other indebtedness	Various	Various		7.0		—		7.0		7.2		—		7.2
Total debt			$	2,341.4	$	(43.6)	$	2,297.8	$	2,344.6	$	(46.1)	$	2,298.5
Less: current portion(5)								(21.1)						(20.9)
Total long-term debt, net of unamortized deferred financing fees							$	2,276.7					$	2,277.6

(1) This caption does not include deferred financing fees related to the Company’s revolving facilities, which are included within “Deferred charges and other assets” on the condensed consolidated balance sheets.

(2) The 2025 Senior Notes were partially repaid on September 8, 2023 using the proceeds of the 2028 Refinance Term Loans.

(3) As of March 31, 2024, under the 2026 Revolving Facility, the Company had a capacity of $375.0 million and $20.8

million outstanding letters of credit. As of March 31, 2024, the Company had funds available for borrowing of $101.7 million (net of the applicable $10.8 million outstanding letters of credit as defined in the secured credit agreement), which reflects the borrowing limit imposed by the springing covenant. The springing covenant applies when 30% or more of the 2026 Revolving Facility’s capacity is drawn which then requires the Company to meet a first lien net leverage ratio (as defined in the secured credit agreement) not to exceed 3.50x at the end of each financial quarter. As of March 31, 2024, the first lien net leverage ratio was 6.96x and the outstanding borrowings did not exceed the 30% threshold. Additionally, the Company is required to pay a quarterly commitment fee in respect of any unused commitments under this facility equal to 0.375% per annum.

(4) As of March 31, 2024, this facility had a borrowing capacity of $150.0 million, and the Company had approximately $150.0 million of accounts receivable available to support this facility, based on the pool of eligible accounts receivable.

(5) The current portion of long-term debt was primarily related to $18.3 million of the scheduled future principal payments on both the 2028 Term Loan B and the 2028 Refinance Term Loans as of March 31, 2024 and December 31, 2023.

The 2028 Refinance Credit Agreement requires the Company to comply with customary affirmative, negative and financial covenants, and contains events of default including (i) relating to a change of control or (ii) failure to maintain at least $100.0 million of Liquidity at the end of any calendar month, and (iii) a cross default to the Credit Agreement. If an event of default occurs, the Term Lenders will be entitled to take various actions, including the acceleration of amounts due under the 2028 Refinance Term Loans. Liquidity is defined under the 2028 Refinance Credit Agreement as a combination of cash and cash equivalents held at certain of the Company’s restricted subsidiaries as well as the funds available for borrowing under both the 2026 Revolving Facility and the Accounts Receivable Securitization Facility, subject to certain restrictions outlined in the 2028 Refinance Credit Agreement.

As of March 31, 2024, the Company was in compliance with all debt covenant requirements under the 2028 Refinance Credit Agreement and the Credit Agreement. The Company had Liquidity of $415.6 million, comprised of $163.8 million of cash and cash equivalents and approximately $251.7 million of funds available for borrowing under both the 2026 Revolving Facility and the Accounts Receivable Securitization Facility, $101.7 million and $150.0 million respectively.

We believe funds provided by operations, our cash and cash equivalent balances, coupled with borrowings available under our 2026 Revolving Facility and our Accounts Receivable Securitization Facility, will be adequate to meet necessary operating and capital expenditures for at least the next twelve months in the current operating environment.

The Company’s ability to repay the 2025 Senior Notes, which mature in September 2025 is also dependent on several factors, including the company’s ability to achieve its forecast cash flows and its ability to maintain minimum liquidity requirements under its related covenants. If the Company is unable to achieve its forecasts, maintain minimum liquidity covenants, or refinance, it could have a material adverse impact on our access to liquidity, results of operation and financial condition.

Accounts Receivable Securitization Facility

The Company has maintained an accounts receivable securitization facility (the “A/R Facility”) since 2010 for the securitization of trade receivables originated by certain of the Company’s Swiss, German, Dutch and U.S. subsidiaries. The A/R Facility is funded through the sale of commercial paper by a special purpose finance entity, the proceeds of which fund the purchase of trade receivables from the Trinseo subsidiaries. Collection accounts related to the trade receivables are pledged to the special purpose entity, which holds a first priority perfected security interest in such accounts and, as a

result, will not be available to the creditors of the Company or its other subsidiaries. The obligations of the Trinseo subsidiaries are also guaranteed by the Company’s subsidiary Trinseo Holding S.à r.l.

On March 28, 2024, the Company amended the A/R Facility to extend its maturity date to November 2025. As amended, the A/R Facility incurs fixed interest charges of 1.65% on outstanding borrowings plus variable commercial paper rates until November 18, 2024, at which time the fixed interest charges will increase to 3.5%. The A/R Facility also incurs fixed charges of 0.80% on available, but undrawn commitments and borrowing limit remains at $150.0 million. The A/R Facility contains standard representations, warranties and covenants, as well as standard termination or perfection events including those relating to (i) insolvency of the Company or certain of its subsidiaries, (ii) cross acceleration, and (iii) failure to maintain at least $250.0 million of liquidity after May 25, 2025. There were $0.5 million of fees incurred in connection with amending the facility which were capitalized and recorded within “Deferred charges and other assets” on the consolidated balance sheet and are being amortized over the remaining term of the facility using the straight-line method.

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FINANCIAL INSTRUMENTS AND DERIVATIVES

3 Months Ended

Mar. 31, 2024

FINANCIAL INSTRUMENTS AND DERIVATIVES

FINANCIAL INSTRUMENTS AND DERIVATIVES

NOTE 11—FINANCIAL INSTRUMENTS AND DERIVATIVES

The Company’s ongoing business operations expose it to various risks, including fluctuating foreign exchange rates, interest rate risk, and commodity price risk, in particular natural gas. To manage these risks, the Company periodically enters into derivative financial instruments, such as foreign exchange forward contracts, interest rate swap agreements, and commodity swap agreements, forward contracts, or options. The Company does not hold or enter into financial instruments for trading or speculative purposes. All derivatives are recorded on the condensed consolidated balance sheets at fair value.

Foreign Exchange Forward Contracts

Certain subsidiaries have assets and liabilities denominated in currencies other than their respective functional currencies, which creates foreign exchange risk. The Company’s principal strategy in managing its exposure to changes in foreign currency exchange rates is to naturally hedge the foreign currency-denominated liabilities on its balance sheet against corresponding assets of the same currency, such that any changes in liabilities due to fluctuations in exchange rates are offset by changes in their corresponding foreign currency assets. In order to further reduce this exposure, the Company also uses foreign exchange forward contracts to economically hedge the impact of the variability in exchange rates on assets and liabilities denominated in certain foreign currencies. These derivative contracts are not designated for hedge accounting treatment and as a result, any mark-to-market fluctuations are recognized currently at each reporting date within loss from continuing operations.

As of March 31, 2024, the Company had open foreign exchange forward contracts with a notional U.S. dollar equivalent absolute value of $347.5 million. The following table displays the notional amounts of the most significant net foreign exchange hedge positions outstanding as of March 31, 2024:

Buy / (Sell)	March 31, 2024
Euro	$	(276.6)
Chinese Yuan	$	(21.7)
South Korean Won	$	(17.9)
Swiss Franc	$	12.9
Indonesian Rupiah	$	(5.9)

Open foreign exchange forward contracts as of March 31, 2024 had maturities occurring over a period of two months.

Foreign Exchange Cash Flow Hedges

From time-to-time, the Company also enters into forward contracts, as deemed appropriate, with the objective of managing the currency risk associated with forecasted U.S. dollar-denominated raw materials purchases by one of its subsidiaries whose functional currency is the euro. By entering into these forward contracts, which are designated as cash flow hedges, the Company buys a designated amount of U.S. dollars and sells euros at the prevailing market rate to mitigate the risk associated with the fluctuations in the euro-to-U.S. dollar foreign currency exchange rates. The qualifying hedge contracts are marked-to-market at each reporting date and any unrealized gains or losses are included in

Accumulated Other Comprehensive Income (“AOCI”) to the extent effective, and reclassified to cost of sales in the period during which the transaction affects earnings or it becomes probable that the forecasted transaction will not occur.

The Company had no open foreign exchange cash flow hedges as of March 31, 2024.

Commodity Cash Flow Hedges & Commodity Economic Hedges

The Company purchases certain commodities, primarily natural gas, to operate facilities and generate heat and steam for various manufacturing processes, which purchases are subject to price volatility. In order to manage the risk of price fluctuations associated with these commodity purchases, as deemed appropriate, the Company may enter into commodity swaps, forward contracts, or options. As of March 31, 2024, the Company had open commodity swap agreements, which effectively convert a portion of its natural gas costs into a fixed rate obligation. These commodity derivatives are designated as cash flow hedges, and as such, the contracts are marked-to-market at each reporting date and any unrealized gains or losses are included in AOCI to the extent effective, and reclassified to cost of sales in the period during which the transaction affects earnings or it becomes probable that the forecasted transaction will not occur.

Open commodity cash flow hedges as of March 31, 2024 had maturities occurring over a period of 9 months and had a notional value of approximately 462 thousand megawatt hours of natural gas purchases.

The Company may also enter into certain commodity swap agreements to economically hedge the impact of these price fluctuations, which are not designated for hedge accounting treatment. Open commodity economic hedges as of March 31, 2024 had maturities occurring over a period of 12 months and had a notional value of approximately 339 thousand megawatt hours of natural gas purchases.

Summary of Derivative Instruments

The following table presents the effect of the Company’s derivative instruments, including those not designated for hedge accounting treatment, on the condensed consolidated statements of operations for the three months ended March 31, 2024 and 2023:

	Location and Amount of Gain (Loss) Recognized in Statements of Operations
	Three Months Ended				Three Months Ended
	March 31, 2024				March 31, 2023
	Cost of sales		Other (expense) income, net		Cost of sales		Other (expense) income, net
Total amount of income and (expense) line items presented in the statements of operations in which the effects of derivative instruments are recorded	$	(843.4)	$	(3.8)	$	(959.1)	$	2.9
The effects of cash flow hedge instruments:
Commodity cash flow hedges
Amount of loss reclassified from AOCI into income	$	(4.8)	$	—	$	(6.4)	$	—
The effects of derivatives not designated as hedge instruments:
Foreign exchange forward contracts
Amount of gain (loss) recognized in income	$	—	$	6.5	$	—	$	(7.8)
Commodity economic hedges
Amount of loss recognized in income	$	(1.6)	$	—	$	(12.4)	$	—

The following table presents the effect of cash flow hedge accounting on AOCI for the three months ended March 31, 2024 and 2023:

`	Gain (Loss) Recognized in AOCI on Balance Sheet
	Three Months Ended
	March 31,
	2024		2023
Designated as Cash Flow Hedges
Commodity cash flow hedges	$	2.7	$	(9.9)
Total	$	2.7	$	(9.9)

	Gain (Loss) Recognized in Other expense (income), net in Statement of Operations
	Three Months Ended
	March 31,
	2024		2023
Settlements and changes in the fair value of forward contracts (not designated as hedges)	$	6.5	$	(7.8)
Remeasurement of foreign currency-denominated assets and liabilities		(8.6)		10.5
Total	$	(2.1)	$	2.7

The Company expects to reclassify in the next twelve months an approximate $9.6 million net loss from AOCI into earnings related to the Company’s outstanding commodity cash flow hedges as of March 31, 2024, based on current commodity price indices.

The following tables summarize the gross and net unrealized gains and losses, as well as the balance sheet classification, of outstanding derivatives recorded in the condensed consolidated balance sheets:

	March 31, 2024
	Foreign
	Exchange		Commodity		Commodity
Balance Sheet	Forward		Economic		Cash Flow
Classification	Contracts		Hedges		Hedges		Total
Asset Derivatives:
Accounts receivable, net of allowance	$	1.2	$	—	$	—	$	1.2
Gross derivative asset position		1.2		—		—		1.2
Less: Counterparty netting		(0.5)		—		—		(0.5)
Net derivative asset position	$	0.7	$	—	$	—	$	0.7
Liability Derivatives:
Accounts payable	$	(0.7)	$	(6.0)	$	(9.6)	$	(16.3)
Gross derivative liability position		(0.7)		(6.0)		(9.6)		(16.3)
Less: Counterparty netting		0.5		—		—		0.5
Net derivative liability position	$	(0.2)	$	(6.0)	$	(9.6)	$	(15.8)
Total net derivative position	$	0.5	$	(6.0)	$	(9.6)	$	(15.1)

	December 31, 2023
	Foreign
	Exchange		Commodity		Commodity
Balance Sheet	Forward		Economic		Cash Flow
Classification	Contracts		Hedges		Hedges		Total
Asset Derivatives:
Accounts receivable, net of allowance	$	0.3	$	—	$	—	$	0.3
Gross derivative asset position		0.3		—		—		0.3
Less: Counterparty netting		(0.3)		—		—		(0.3)
Net derivative asset position	$	—	$	—	$	—	$	—
Liability Derivatives:
Accounts payable	$	(4.8)	$	(7.2)	$	(13.7)	$	(25.7)
Other noncurrent obligations		—		(0.9)		(0.7)		(1.6)
Gross derivative liability position		(4.8)		(8.1)		(14.4)		(27.3)
Less: Counterparty netting		0.3		—		—		0.3
Net derivative liability position	$	(4.5)	$	(8.1)	$	(14.4)	$	(27.0)
Total net derivative position	$	(4.5)	$	(8.1)	$	(14.4)	$	(27.0)

Forward contracts, interest rate swaps, commodity forward contracts, swaps, or options, and cross currency swaps are entered into with a limited number of counterparties, each of which allows for net settlement of all contracts through a single payment in a single currency in the event of a default on or termination of any one contract. As such, in accordance with the Company’s accounting policy, these derivative instruments are recorded on a net basis by counterparty within the condensed consolidated balance sheets.

Refer to Notes 12 and 17 of the condensed consolidated financial statements for further information regarding the fair value of the Company’s derivative instruments and the related changes in AOCI.

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FAIR VALUE MEASUREMENTS

3 Months Ended

Mar. 31, 2024

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS

NOTE 12—FAIR VALUE MEASUREMENTS

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Assets and liabilities measured at fair value are classified using the following hierarchy, which is based upon the transparency of inputs to the valuation as of the measurement date.

Level 1—Valuation is based upon quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2—Valuation is based upon quoted prices for similar assets and liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument.

Level 3—Valuation is based upon other unobservable inputs that are significant to the fair value measurement.

The following table summarizes the basis used to measure certain assets and liabilities at fair value on a recurring basis in the condensed consolidated balance sheets as of March 31, 2024 and December 31, 2023:

	March 31, 2024
	Quoted Prices in Active Markets for Identical Items		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets (Liabilities) at Fair Value	(Level 1)		(Level 2)		(Level 3)		Total
Foreign exchange forward contracts—Assets	$	—	$	0.7	$	—	$	0.7
Foreign exchange forward contracts—(Liabilities)		—		(0.2)		—		(0.2)
Commodity economic hedges—(Liabilities)		—		(6.0)		—		(6.0)
Commodity cash flow hedges—(Liabilities)		—		(9.6)		—		(9.6)
Total fair value	$	—	$	(15.1)	$	—	$	(15.1)

	December 31, 2023
	Quoted Prices in Active Markets for Identical Items		Significant Other Observable Inputs		Significant Unobservable Inputs
Liabilities at Fair Value	(Level 1)		(Level 2)		(Level 3)		Total
Foreign exchange forward contracts—(Liabilities)	$	—	$	(4.5)	$	—	$	(4.5)
Commodity economic hedges—(Liabilities)		—		(8.1)		—		(8.1)
Commodity cash flow hedges—(Liabilities)		—		(14.4)		—		(14.4)
Total fair value	$	—	$	(27.0)	$	—	$	(27.0)

The Company uses an income approach to value its derivative instruments, utilizing discounted cash flow techniques, considering the terms of the contract and observable market information available as of the reporting date, such as interest rate yield curves and currency spot and forward rates. Significant inputs to the valuation for these derivative instruments are obtained from broker quotations or from listed or over-the-counter market data, and are classified as Level 2 in the fair value hierarchy.

Nonrecurring Fair Value Measurements

The Company measured certain financial assets at fair value on a nonrecurring basis during the year ended December 31, 2023, which were still held as of March 31, 2024. These financial assets represent the Company’s styrene monomer assets in Boehlen, Germany, which it continued to operate until the fourth quarter of 2022 when the Company decided to close this plant in connection with the asset restructuring plan. Refer to Note 4 for further information. These assets were measured at fair value using underlying fixed asset records in conjunction with the use of industry experience and available market data, which are classified as Level 3 significant unobservable inputs in the fair value hierarchy. As of March 31, 2024 and December 31, 2023, the value of the Boehlen styrene monomer assets are recorded at $3.2 and $3.2 million, respectively, within the Company’s condensed consolidated balance sheets herein.

There were no other financial assets or liabilities measured at fair value on a nonrecurring basis as of December 31, 2023.

Fair Value of Debt Instruments

The following table presents the estimated fair value of the Company’s outstanding debt not carried at fair value as of March 31, 2024 and December 31, 2023:

	As of		As of
	March 31, 2024		December 31, 2023
2029 Senior Notes	$	146.7	$	180.4
2025 Senior Notes		92.8		98.5
2028 Term Loan B		539.9		564.9
2028 Refinance Term Loans		1,091.7		1,087.1
Total fair value	$	1,871.1	$	1,930.9

The fair value of the Company’s debt facilities above (each Level 2 securities) is determined using over-the-counter market quotes and benchmark yields received from independent vendors. The fair value amount presented reflect the Company’s carrying value of debt, net of original issuance discount.

There were no other significant financial instruments outstanding as of March 31, 2024 and December 31, 2023.

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COMMITMENTS AND CONTINGENCIES

3 Months Ended

Mar. 31, 2024

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES

NOTE 13—COMMITMENTS AND CONTINGENCIES

Environmental Matters

Accruals for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated based on current law, existing technologies and other information. Pursuant to the terms of the agreement associated with the Company’s formation, the pre-closing environmental liabilities were retained by Dow, and Dow agreed, subject to temporal, monetary, and other limitations to indemnify the Company from and against environmental liabilities incurred or relating to the predecessor periods. Other than certain immaterial environmental liabilities assumed as part of the PMMA Acquisition and the Aristech Surfaces Acquisition, no material environmental claims have been asserted against the Company, and the Company does not have any material accrued obligations for any Superfund Sites. As of March 31, 2024 and December 31, 2023, the Company had $1.3 million of accrued obligations for environmental remediation or restoration costs, which were recorded at fair value within the opening balance sheets of the PMMA business and Aristech Surfaces during 2021.

On March 24, 2023, due to equipment failure at the Bristol, Pennsylvania facility, operated by our wholly-owned subsidiary, Altuglas LLC, an accidental release of a latex emulsion product occurred, which ultimately flowed into a local waterway (the “Bristol Spill”). We reported the event and cooperated closely with local, state, and federal authorities on the response activities. Water sampling conducted by the authorities did not detect site-related material in the waterway. See “Litigation Matters” below for information on environmental proceedings related to this incident. In the event of one or more adverse determinations related to this matter, it is possible that the ultimate liability resulting from this matter and the impact on the Company’s results of operations could be material.

Inherent uncertainties exist in the Company’s potential environmental liabilities primarily due to unknown conditions, whether future claims may fall outside the scope of the indemnity, changing governmental regulations and legal standards regarding liability, and evolving technologies for handling site remediation and restoration. In connection with the Company’s existing indemnification, the possibility is considered remote that environmental remediation costs will have a material adverse impact on the condensed consolidated financial statements over the next 12 months.

Purchase Commitments

In the normal course of business, the Company has certain raw material purchase contracts where it is required to purchase certain minimum volumes at current market prices. These commitments range from one to four years. In certain raw material purchase contracts, the Company has the right to purchase less than the required minimums and pay a liquidated damages fee, or, in case of a permanent plant shutdown, to terminate the contracts. In such cases, these obligations would be less than the annual commitment as disclosed in the Notes to Consolidated Financial Statements included in the Annual Report.

Asset Retirement Obligations

The Company has built certain manufacturing facilities on leased land and is required to remove these facilities at the end of the corresponding contract term. Legal obligations for these demolition and decommissioning activities exist in connection with the retirement of these assets triggered upon closure of the facilities. In instances when the Company plans to continue operations at these facilities indefinitely, and therefore, a reasonable estimate of fair value cannot be determined, an asset retirement obligation is not recognized.

In connection with the Asset Restructuring Plan as described within Note 4, the Company concluded the Boehlen, Germany site no longer had an indeterminate life. Accordingly, during the fourth quarter of 2022, the Company recorded the fair value of an asset retirement obligation and a corresponding asset retirement cost, which was capitalized as part of the carrying amount of the related long-lived assets and depreciated over the asset’s shortened useful life. The asset retirement cost was fully depreciated as of March 31, 2024.

Change in asset retirement obligation
Balance at December 31, 2023	$	20.2
Obligations incurred and adjustments to estimated obligations		—
Settlements		(1.8)
Accretion expense		0.2
Currency translation adjustment		(0.5)
Balance at March 31, 2024	$	18.1

Accretion expense is included within “Selling, general and administrative expenses” in the condensed consolidated statement of operations. The current portion of the asset retirement obligation is recorded within “Accrued expenses and other current liabilities” and the long-term portion is recorded within “Other noncurrent obligations” in the condensed consolidated balance sheets. As of March 31, 2024 and December 31, 2023, the current portion was $8.8 million and $10.7 million, respectively, and the long-term portion was $9.3 million and $9.5 million, respectively.

Litigation Matters

From time to time, the Company may be subject to various legal claims and proceedings incidental to the normal conduct of business, relating to such matters as employees, product liability, antitrust/competition, past waste disposal practices and release of chemicals into the environment. While it is impossible at this time to determine with certainty the ultimate outcome of these routine claims, the Company does not believe that the ultimate resolution of these claims will have a material adverse effect on the Company’s results of operations, financial condition or cash flow. Legal costs, including those legal costs expected to be incurred in connection with a loss contingency, are expensed as incurred.

Legal Proceedings related to the Bristol Spill

(a) Timothy McGraw, Emily Cohen & Danielle Byrd v. Altuglas LLC and Trinseo LLC (United States District Court for the Eastern District of Pennsylvania)

On March 29, 2023, a putative class action complaint was filed which seeks to certify a class that could potentially include all persons and entities that reside in the area served by the Baxter Drinking Water Treatment Plant. The plaintiffs allege claims of breach of duty of care based on negligence as a result of the Bristol Spill, as well as other causes of action, and seek compensatory damages, restitution, or refund of damages, including actual, statutory, and punitive damages, as well as injunctive relief. On May 12, 2023, the Company filed notice to remove the case from Pennsylvania state court to United States District Court for the Eastern District of Pennsylvania, with immediate effect. On May 19, 2023, the Company also filed a motion to dismiss with the U.S. district court, on the grounds that the alleged harms do not fall within the parameters of the relevant public and private nuisance or negligence laws. On June 2, 2023, plaintiffs objected to federal jurisdiction and asked the court to remand the action to state court. On August 23, 2023, plaintiffs filed a voluntary dismissal of the federal complaint, which was granted on August 29, 2023. The parties signed a settlement agreement in December 2023, and on January 2, 2024, plaintiffs refiled their claim in the Court of Common Pleas of Philadelphia County and simultaneously submitted an unopposed motion for an order to preliminarily approve a class settlement. On March 15, 2024, an Order Preliminarily Approving Settlement was entered by the Court of Common Pleas, which

provides for preliminary approval of the negotiated settlement, subject to a final approval hearing, defines members of the settlement class and appoints a settlement administrator to send notice to settlement class members. In the fourth quarter of 2023, the Company established an accrual for the estimated resolution of the class action complaint. Pursuant to the terms of the settlement agreement, $2.7 million was paid into escrow in April 2024, which amount was covered by the Company’s insurance coverage. The Order Preliminarily Approving Settlement provides for a Final Approval Hearing to be held on September 23, 2024.

(b) Environmental Proceedings

On March 25, 2023, the Company received a Notice of Federal Interest from the United States Coast Guard (“USCG”), identifying the Company as a “potentially responsible party” (“PRP”) related to the Bristol Spill. The Company also received a Notice of Federal Assumption and an Administrative Order, dated April 20, 2023 from the USCG, identifying the Company as a PRP related to the Bristol Spill. The USCG notices and order do not designate specific fines or penalties against the Company. In October 2023, the Pennsylvania Department of Environmental Protection (PADEP) notified the Company of its intent to impose penalties related to a Notice of Violation dated April 26, 2023 alleging water violations associated with the Spill. Discussions between the Company and PADEP are ongoing. In December 2023, the Company established an accrual for the estimated resolution of this matter, and such loss is not expected to be material to our business.

It is not possible at this time for the Company to estimate its ultimate liability pursuant to these matters or other potential administrative or criminal actions related to the Bristol Spill, whether a material loss to our business is probable or remote, or estimate a potential range of loss, if any.

Synthos Matter

On November 21, 2022, the Company received formal notice from the German Arbitration Institute that Synthos had initiated an arbitration dispute on October 14, 2022 against Trinseo and its following subsidiaries: Trinseo Deutschland GmbH, Trinseo Belgium BV, Trinseo Europe GmbH, and Trinseo Export GmbH, related to Synthos’ purchase of Trinseo’s Rubber Business in 2021.

Synthos and Trinseo are parties to an asset purchase agreement (“APA”) dated May 21, 2021, whereby Trinseo transferred its Rubber Business to Synthos, pending regulatory approval and other administrative pre-closing conditions, for an enterprise value of approximately $491.0 million. This transaction formally closed on December 1, 2021. Synthos claims that Trinseo did not properly disclose certain information including the natural gas pricing mechanism for the steam which is supplied by a third party to the Rubber Business. Synthos is seeking non-monetary restitution and monetary damages related to the spike of utility prices in Germany that commenced in the fall of 2021. On December 7, 2023, Synthos filed an adjusted motion with the German Arbitration Institute clarifying its claims for monetary damages. On April 26, 2024, Trinseo filed a statement of defense and counterclaim in response to Synthos’ adjusted motion.

The Company believes it has valid and prevailing defenses to Synthos’ claims and intends to vigorously defend itself against all allegations.

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PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS

3 Months Ended

Mar. 31, 2024

PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS

PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS

NOTE 14—PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS

The components of net periodic benefit costs for all significant plans were as follows:

	Three Months Ended				Three Months Ended
	March 31,				March 31,
	Non-U.S. Defined Benefit Pension Plans				U.S. Defined Benefit Pension
	2024		2023		2024		2023
Net periodic benefit cost
Service cost	$	2.1	$	2.0	$	0.1	$	0.1
Interest cost		2.4		1.7		0.2		0.2
Expected return on plan assets		(1.0)		(0.2)		(0.2)		(0.1)
Amortization of prior service credit		(0.1)		(0.1)		—		—
Amortization of net gain		(0.3)		(0.8)		—		—
Net periodic benefit cost	$	3.1	$	2.6	$	0.1	$	0.2

The Company had less than $0.1 million of net periodic benefit costs for its other postretirement plans for the three months ended March 31, 2024 and 2023.

Service cost related to the Company’s defined benefit pension plans and other postretirement plans is included within “Cost of sales” and “Selling, general and administrative expenses,” whereas all other components of net periodic benefit cost are included within “Other expense (income), net” in the condensed consolidated statements of operations. As of March 31, 2024 and December 31, 2023, the Company’s benefit obligations included primarily in “Other noncurrent obligations” in the condensed consolidated balance sheets were $192.3 million and $197.0 million, respectively.

The Company made cash contributions and benefit payments to unfunded plans of approximately $2.5 million during the three months ended March 31, 2024. The Company expects to make additional cash contributions, including benefit payments to unfunded plans, of approximately $6.7 million to its defined benefit plans for the remainder of 2024.

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SHARE-BASED COMPENSATION

3 Months Ended

Mar. 31, 2024

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION

NOTE 15—SHARE-BASED COMPENSATION

Refer to the Annual Report for definitions of capitalized terms not included herein and further background on the Company’s share-based compensation programs included in the tables below.

The following table summarizes the Company’s share-based compensation expense for the three months ended March 31, 2024 and 2023, as well as unrecognized compensation cost as of March 31, 2024:

					As of
	Three Months Ended				March 31, 2024
	March 31,				Unrecognized		Weighted
	2024		2023		Compensation Cost		Average Years
RSUs	$	2.4	$	4.8	$	6.5	1.4
Options		0.8		2.6		1.1	1.2
PSUs		0.6		0.8		4.8	2.0
Restricted Cash Units ("RCUs")		2.1		—		3.0 (1)	1.9
Total share-based compensation expense	$	5.9	$	8.2

(1) Unrecognized Compensation Cost related to RCU awards as of March 31, 2024 is calculated using the stock price as of March 31, 2024.

The following table summarizes awards granted and the respective weighted average grant date fair value for the three months ended March 31, 2024:

	Three Months Ended
	March 31, 2024
	Awards Granted		Weighted Average Grant Date Fair Value per Award
RSUs		646,972	$	4.38
Options		319,407		2.48
PSUs		575,475		2.81
RCUs		1,074,119		4.85

Option Awards

The following are the weighted average assumptions used within the Black-Scholes pricing model for the Company’s option awards granted during the three months ended March 31, 2024:

	Three Months Ended
	March 31, 2024
Expected term (in years)	5.50
Expected volatility	64.12	%
Risk-free interest rate	4.28	%
Dividend yield	0.73	%

The expected volatility assumption is determined based on the historical volatility of the Company’s publicly traded ordinary shares. The expected term of option awards represents the period of time that option awards granted are expected to be outstanding. For the option awards granted during the three months ended March 31, 2024, the simplified method was used to calculate the expected term, given the Company’s limited historical exercise data. The risk-free interest rate for the periods within the expected term of option awards is based on the U.S. Treasury yield curve in effect at the time of grant. The dividend yield is estimated based on historical and expected dividend activity.

Performance Share Units (PSUs)

The following are the weighted average assumptions used within the Monte Carlo valuation model for PSUs granted during the three months ended March 31, 2024:

		Three Months Ended
		March 31, 2024
Expected term (in years)		3.00
Expected volatility		65.40	%
Risk-free interest rate		4.40	%
Share price	$	4.39

Determining the fair value of PSUs requires considerable judgment, including estimating the expected volatility of the price of the Company’s ordinary shares, the correlation between the Company’s share price and that of its peer companies, and the expected rate of interest. The expected volatility for each grant is determined based on the historical volatility of the Company’s ordinary shares. The expected term of PSUs represents the length of the performance period. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for a duration equivalent to the performance period. The share price is the closing price of the Company’s ordinary shares on the grant date.

Restricted Cash Units (RCUs)

In the three months ending March 31, 2024, 1,074,119 restricted cash units ("RCUs") were awarded to certain employees and represent the right to receive a cash payment at the end of a vesting period, subject to the employee's continued employment. In general, RCUs vest in equal installments each year over 3 years. RCUs are cash-settled with the value of each vested RCU equal to the lower of the closing price per share of our common stock on the vesting date or a specified per share price cap. Certain awards are subject to a specified price floor. We determined that RCUs are in-substance liabilities accounted for as liability instruments in accordance with ASC 718, Compensation-Stock Compensation, due to this cash settlement feature. RCUs are remeasured based on the closing price per share of our common stock at the end of each reporting period. The liability associated with the RCUs is included in accrued expenses and other current liabilities in the condensed consolidated balance sheet. No RCU awards were vested or forfeited in the three months ending March 31, 2024.

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SEGMENTS AND GEOGRAPHIC INFORMATION

3 Months Ended

Mar. 31, 2024

SEGMENTS AND GEOGRAPHIC INFORMATION

SEGMENTS AND GEOGRAPHIC INFORMATION

NOTE 16—SEGMENTS AND GEOGRAPHIC INFORMATION

Effective January 1, 2024, the Company realigned its reporting segments to reflect the new model under which the business is managed, and results are reviewed by the chief executive officer, the Company’s chief operating decision maker. Following this change, the Company is operating under five segments, all of which remain unchanged from the Company’s prior six segment segmentation: Engineered Materials, Latex Binders, Plastics Solutions, Polystyrene, and Americas Styrenics.

The Company’s Feedstocks segment, which included the Company’s production and procurement of styrene monomer outside of North America, was eliminated as a result of the closures of the styrene plants located in Boehlen, Germany and Terneuzen, the Netherlands under an asset restructuring plan. Styrene monomer is a key raw material in many of the Company’s products, including polystyrene, styrene-butadiene latex (“SB latex”), and acrylonitrile-butadiene-styrene (“ABS”) resins. The Company no longer produces styrene, but instead purchases all of our styrene needs from third parties. Therefore, the information in the tables below has been adjusted to show the historical results of the Feedstocks segment within the segments that consumed styrene monomer in their end products, Latex Binders, Plastics Solutions and Polystyrene.

The Engineered Materials segment includes the Company’s compounds and blends products sold into higher growth and value applications, such as consumer electronics and medical, as well as soft thermoplastic elastomers (“TPEs”) products which are sold into markets such as footwear and automotive. Additionally, following the PMMA Acquisition and the Aristech Surfaces Acquisition in 2021, the Engineered Materials segment also includes PMMA and activated methyl methacrylates (“MMA”) products, which are sold into a variety of applications including automotive, building & construction, medical, consumer electronics, and wellness, among others. The Latex Binders segment produces SB latex and other latex polymers and binders, primarily for coated paper and packaging board, carpet and artificial turf backings, as well as a number of performance latex binders applications, such as adhesive, building and

construction and the technical textile paper market. The Plastics Solutions segment contains the results of the ABS, styrene-acrylonitrile (“SAN”), and polycarbonate (“PC”) businesses, as well as compounds and blends for automotive and other applications. The Plastics Solutions segment also includes the results of Heathland, which was acquired in the first quarter of 2022. The Polystyrene segment includes a variety of general purpose polystyrenes (“GPPS”) and polystyrene that has been modified with polybutadiene rubber to increase its impact resistant properties (“HIPS”). Lastly, the Americas Styrenics segment consists solely of the operations of the Company’s 50%-owned joint venture, Americas Styrenics, a producer of both styrene monomer and polystyrene in North America.

The following table provides disclosure of the Company’s segment Adjusted EBITDA, which is used to measure segment operating performance and is defined below, for the three months ended March 31, 2024 and 2023. Asset and intersegment sales information by reporting segment are not regularly reviewed or included with the Company’s reporting to the chief operating decision maker. Therefore, this information has not been disclosed below. Refer to Note 3 for the Company’s net sales to external customers by segment for the three months ended March 31, 2024 and 2023.

	Engineered		Latex		Plastics				Americas		Total Segment
Three Months Ended (1)	Materials		Binders		Solutions		Polystyrene		Styrenics		Adjusted EBITDA
March 31, 2024	$	4.3	$	25.7	$	22.7	$	12.6	$	6.1	$	71.4
March 31, 2023	$	(11.7)	$	24.0	$	23.6	$	8.9	$	17.6	$	62.4

(1) The Company’s primary measure of segment operating performance is Adjusted EBITDA, which is defined as income from continuing operations before interest expense, net; provision for income taxes; depreciation and amortization expense; loss on extinguishment of long-term debt; asset impairment charges; gains or losses on the dispositions of businesses and assets; restructuring charges; acquisition related costs and benefits and other items. Segment Adjusted EBITDA is a key metric that is used by management to evaluate business performance in comparison to budgets, forecasts, and prior year financial results, providing a measure that management believes reflects core operating performance by removing the impact of transactions and events that would not be considered a part of core operations. Other companies in the industry may define segment Adjusted EBITDA differently than the Company, and as a result, it may be difficult to use segment Adjusted EBITDA, or similarly named financial measures, that other companies may use to compare the performance of those companies to the Company’s segment performance.

The reconciliation of income (loss) from continuing operations before income taxes to segment Adjusted EBITDA is as follows:

	Three Months Ended
	March 31,
	2024		2023
Loss before income taxes	$	(70.1)	$	(65.6)
Interest expense, net		63.0		38.3
Depreciation and amortization		45.0		56.0
Corporate Unallocated(2)		26.4		26.1
Adjusted EBITDA Addbacks(3)		7.1		7.6
Segment Adjusted EBITDA	$	71.4	$	62.4

(2) Corporate unallocated includes corporate overhead costs and certain other income and expenses.

(3) Adjusted EBITDA addbacks for the three months ended March 31, 2024 and 2023 are as follows:

	Three Months Ended
	March 31,
	2024		2023
Net gain on disposition of businesses and assets	$	(3.6)	$	—
Restructuring and other charges (Note 4)		9.4		3.7
Asset impairment charges or write-offs (Note 12)		—		0.3
Other items (a)		1.3		3.6
Total Adjusted EBITDA Addbacks	$	7.1	$	7.6

(a) Other items for the three months ended March 31, 2024 and 2023 primarily relate to costs incurred in conjunction with certain of the Company’s strategic initiatives. Other items for the three months ended March 31, 2023 also relate to our transition to a new enterprise resource planning system.

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ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

3 Months Ended

Mar. 31, 2024

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

NOTE 17—ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

The components of AOCI, net of income taxes, consisted of:

	Cumulative		Pension & Other
	Translation		Postretirement Benefit			Cash Flow
Three Months Ended March 31, 2024 and 2023	Adjustments		Plans, Net			Hedges, Net	Total
Balance as of December 31, 2023	$	(141.9)	$	17.1	$	(4.8)	$	(129.6)
Other comprehensive income (loss)		(11.8)		—		0.1		(11.7)
Amounts reclassified from AOCI to net income(1)		—		(0.4)		4.3		3.9
Balance as of March 31, 2024	$	(153.7)	$	16.7	$	(0.4)	$	(137.4)
Balance as of December 31, 2022	$	(151.2)	$	29.0	$	(9.1)	$	(131.3)
Other comprehensive income (loss)		10.5		—		(13.2)		(2.7)
Amounts reclassified from AOCI to net income (1)		—		0.3		5.8		6.1
Balance as of March 31, 2023	$	(140.7)	$	29.3	$	(16.5)	$	(127.9)

(1) The following is a summary of amounts reclassified from AOCI to net income (loss) for the three months ended March 31, 2024 and 2023:

	Three Months Ended
	March 31,				Statements of Operations
AOCI Components	2024		2023		Classification
Cash flow hedging items
Commodity cash flow hedges	$	4.8	$	6.4	Cost of sales
Total before tax		4.8		6.4
Tax effect		(0.5)		(0.6)	Provision for (benefit from) income taxes
Total, net of tax	$	4.3	$	5.8
Amortization of pension and other postretirement benefit plan items
Prior service credit	$	(0.1)	$	0.1	(a)
Net actuarial (gain) loss		(0.4)		0.3	(a)
Total before tax		(0.5)		0.4
Tax effect		0.1		(0.1)	Provision for (benefit from) income taxes
Total, net of tax	$	(0.4)	$	0.3

(a) These AOCI components are included in the computation of net periodic benefit costs (see Note 14).

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BASIS OF PRESENTATION (Policies)

3 Months Ended

Mar. 31, 2024

BASIS OF PRESENTATION

Basis of Presentation

The unaudited interim condensed consolidated financial statements of Trinseo PLC and its subsidiaries (the “Company”) as of and for the periods ended March 31, 2024 and 2023 were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and reflect all adjustments, consisting only of normal recurring adjustments, which, in the opinion of management, are considered necessary for the fair statement of the results for the periods presented. Because they cover interim periods, the statements and related notes to the financial statements do not include all disclosures normally provided in annual financial statements, and therefore, these statements should be read in conjunction with the 2023 audited consolidated financial statements included within the Company’s Annual Report on Form 10-K (“Annual Report”) filed with the Securities and Exchange Commission (“SEC”) on February 23, 2024. The Company’s condensed consolidated financial statements presented herein reflect the latest estimates and assumptions made by management that affect the reported amounts and related disclosures as of and for the period ended March 31, 2024. However, actual results could differ from these estimates and assumptions.

The December 31, 2023 condensed consolidated balance sheet data presented herein was derived from the Company’s December 31, 2023 audited consolidated financial statements, but does not include all disclosures required by GAAP for annual periods.

Effective January 1, 2024, the Company’s Feedstocks segment, which included the Company’s production and procurement of styrene monomer outside of North America, was eliminated as a result of the closures of the styrene plants located in Boehlen, Germany and Terneuzen, the Netherlands under an asset restructuring plan. As a result, the Company realigned its reporting segments to reflect the new model under which the business is managed with five segments, all of which remain unchanged from the Company’s prior six segment segmentation: Engineered Materials, Latex Binders, Plastics Solutions, Polystyrene, and Americas Styrenics. Therefore, certain prior year information has been adjusted to show the historical results of the Feedstocks segment within the segments that consumed styrene monomer in their end products, Latex Binders, Plastics Solutions and Polystyrene. Refer to Notes 3, 4 and 16 for further information. Throughout this Quarterly Report, unless otherwise indicated, amounts and activity are presented on a continuing operations basis.

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RESTRUCTURING ACTIVITIES (Tables)

3 Months Ended

Mar. 31, 2024

RESTRUCTURING ACTIVITIES

Schedule of restructuring charges

	Three Months Ended				Cumulative
	March 31,				Life-to-date
	2024		2023		Charges		Segment
Asset Optimization and Corporate Restructuring(1)
Engineered Materials:
Accelerated depreciation	$	—	$	—	$	9.3	Engineered Materials
Employee termination benefits		—		—		1.2	Engineered Materials
Decommissioning and other		1.1		—		3.7	Engineered Materials
Plastics Solutions(5):
Accelerated depreciation	$	—	$	—	$	19.6	Plastics Solutions
Employee termination benefits		(0.7)		—		4.7	Plastics Solutions
Contract terminations		3.8		—		6.3	Plastics Solutions
Decommissioning and other		1.8		—		6.8	Plastics Solutions
Corporate:
Employee termination benefits	$	1.2	$	—	$	10.0	N/A(2)
Asset Optimization and Corporate Restructuring Subtotal	$	7.2	$	—	$	61.6
Asset Restructuring Plan(3)
Plastics Solutions(5):
Accelerated depreciation	$	—	$	0.9	$	27.4	Plastics Solutions(6)
Employee termination benefits		—		(0.2)		3.7	Plastics Solutions(6)
Contract terminations		1.7		2.5		10.0	Plastics Solutions(6)
Decommissioning and other		0.3		0.5		4.5	Plastics Solutions(6)
Plastics Solutions:
Accelerated depreciation	$	—	$	—	$	1.4	Plastics Solutions
Employee termination benefits		(0.6)		(0.4)		2.4	Plastics Solutions
Decommissioning and other		—		0.7		1.9	Plastics Solutions
Engineered Materials:
Accelerated depreciation	$	—	$	3.1	$	6.3	Engineered Materials
Employee termination benefits		—		—		2.7	Engineered Materials
Decommissioning and other		—		0.6		1.3	Engineered Materials
Asset Restructuring Plan Subtotal	$	1.4	$	7.7	$	61.6
Transformational Restructuring Program(4)
Employee termination benefits	$	—	$	—	$	6.7
Transformational Restructuring Program Subtotal	$	—	$	—	$	6.7	N/A(2)
Total Restructuring Charges	$	8.6	$	7.7

(1) On August 23, 2023, the Company announced a restructuring plan to optimize its polymethyl methacrylates (“PMMA”) sheet network, primarily in Europe, consolidate manufacturing operations and certain other workforce reductions to streamline its general & administrative network. The Asset Optimization and Corporate Restructuring plan includes closure of certain plants and product lines, including (i) closure of manufacturing operations at the Company’s PMMA cast sheets plant in Bronderslev, Denmark, (ii) closure of manufacturing operations at the Company’s batch polyester tray casting plant in Belen, New Mexico, and (iii) closure of its PMMA extruded sheet production line at its Rho, Italy plant.

On October 26, 2023, the management team of the Company, with authorization from the Company’s Board of Directors, approved additional actions to discontinue styrene production at the Company’s Terneuzen, the Netherlands plant, decommission the styrene plant assets, as well as related workforce reductions.

During the three months ended March 31, 2024, the Company incurred employee termination benefit charges, net of $0.5 million. The majority of these charges are expected to be paid through second quarter of 2025. The Company also incurred decommissioning and other charges of $2.9 million, as well as contract termination charges of $3.8 million.

The Company expects to incur contract termination charges of $4.8 million and an incremental $16.2 million of decommissioning and other charges through the end of 2025.

In March 2024, the Company entered into two separate agreements to sell its land, buildings and equipment in Bronderslev, Denmark and Belen, New Mexico for gross cash consideration of approximately $4.7 million. As of March 31, 2024, the cash proceeds of $2.9 million were received into the Company’s restricted cash account to be released upon completion of final regulatory documentation. The Company recorded pre-tax gain on sales of $3.6 million during the three ended March 31, 2024, which was recorded within “Selling, general and administrative expenses” in the condensed consolidated statements of operations.

(2) Reflects certain employee termination benefit charges associated with streamlining internal general & administrative network. As these employee termination benefit charges were identified as a corporate-related activity, the charges related to this portion of the Asset Optimization and Corporate Restructuring plan were not allocated to a specific segment, but rather included within corporate unallocated.

(3) In December 2022, the Company announced an asset restructuring plan designed to reduce costs, improve profitability, reduce exposure to cyclical markets and elevated natural gas prices, and address market overcapacity. The asset restructuring plan includes (i) closure of manufacturing operations at the styrene production facility in Boehlen, Germany, (ii) closure of one of its production lines at the Stade, Germany polycarbonate plant, and (iii) closure of the PMMA sheet manufacturing site in Matamoros, Mexico. The program is expected to be substantially completed by 2026.

In connection with this restructuring plan, during the three months ended March 31, 2024 and 2023, the Company incurred employee termination benefit charges, net of $(0.6) million and $(0.6) million, respectively, contract termination charges of $1.7 million and $2.5 million, respectively, and decommissioning and other charges of $0.3 million and $1.8 million, respectively. The Company incurred accelerated depreciation charges of $4.0 million during the three months ended March 31, 2023.

The Company expects to incur incremental contract termination charges of $10.5 million, decommissioning and other charges of $0.5 million, as well as a limited amount of incremental employee termination benefit charges within the Plastics Solution segment, the majority of which is expected to be paid by the end of 2024.

(4) In May 2021, the Company approved a transformational restructuring program associated with the Company’s strategic initiatives. The transformational restructuring program was completed as of December 31, 2023. As this was identified as a corporate-related activity, the charges related to this restructuring program were not allocated to a specific segment, but rather included within corporate unallocated.

(5) As of January 2024, the Feedstocks segment was eliminated as a result of the closures of the styrene plants located in Boehlen, Germany and Terneuzen, the Netherlands under an asset restructuring plan. Prior period balances in this table have been reclassified to reflect the elimination of the Feedstocks reportable segment effective January 1, 2024. Asset Optimization charges relate to Terneuzen plant shutdown and Asset Restructuring Plan charges relate to the shutdown of Boehlen site. These charges were previously recognized under Feedstocks segment but will be allocated to Plastics Solutions segment starting January 1, 2024 and onward.

(6) Prior period balances in this table have been reclassified to reflect the elimination of the Feedstocks reportable segment effective January 1, 2024. For the three months ended March 31, 2023, Latex Binders was allocated $0.1 million of accelerated depreciation, $0.4 million of contract termination costs, $0.1 million decommissioning and other charges; Plastics Solutions was allocated $0.2 million of accelerated depreciation, $(0.1) million employee termination benefits, $0.6 million of contract termination costs, $0.1 million decommissioning and other charges; and Polystyrene was allocated $0.6 million of accelerated depreciation, $(0.1) million employee termination benefits, $1.5 million of contract termination costs, $0.3 million decommissioning and other charges.

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INCOME TAXES (Tables)

3 Months Ended

Mar. 31, 2024

INCOME TAXES

Schedule of Effective Tax Rate

	Three Months Ended
	March 31,
	2024			2023
Effective income tax rate		(7.7)	%		25.4	%

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EARNINGS PER SHARE (Tables)

3 Months Ended

Mar. 31, 2024

EARNINGS PER SHARE

Schedule of Earnings per Share Basic and Diluted

	Three Months Ended
	March 31,
(in millions, except per share data)	2024		2023
Earnings:
Net loss	$	(75.5)	$	(48.9)
Shares:
Weighted average ordinary shares outstanding		35.3		35.0
Dilutive effect of RSUs, option awards, and PSUs(1)		—		—
Diluted weighted average ordinary shares outstanding		35.3		35.0
Loss per share:
Loss per share‒basic	$	(2.14)	$	(1.40)
Loss per share‒diluted	$	(2.14)	$	(1.40)

(1) Refer to Note 15 for discussion of RSUs, option awards, and PSUs granted to certain Company directors and employees. As the Company recorded a net loss from continuing operations for the three months ended March 31, 2024 and March 31, 2023, potential shares related to equity-based awards have been excluded from the calculation of diluted EPS, as doing so would be anti-dilutive.

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INVENTORIES (Tables)

3 Months Ended

Mar. 31, 2024

INVENTORIES

Schedule of Inventories

	March 31,		December 31,
	2024		2023
Finished goods	$	190.2	$	162.4
Raw materials and semi-finished goods		199.4		200.9
Supplies		41.6		41.4
Total	$	431.2	$	404.7

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INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Tables)

3 Months Ended

Mar. 31, 2024

INVESTMENTS IN UNCONSOLIDATED AFFILIATES

Summarized financial information of unconsolidated affiliates

	Three Months Ended
	March 31,
	2024		2023
Sales	$	386.0	$	443.3
Gross profit	$	11.6	$	52.9
Net income (loss)	$	(3.7)	$	37.8

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GOODWILL (Tables)

3 Months Ended

Mar. 31, 2024

GOODWILL

Changes in Carrying Amount of Goodwill, by Segment

	Engineered		Latex		Plastics				Americas
	Materials		Binders		Solutions		Polystyrene		Styrenics		Total
Balance at December 31, 2023	$	—	$	15.4	$	44.0	$	4.4	$	—	$	63.8
Foreign currency impact		—		(0.4)		(1.0)		(0.1)		—		(1.5)
Balance at March 31, 2024	$	—	$	15.0	$	43.0	$	4.3	$	—	$	62.3

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LONG TERM DEBT & AVAILABLE FACILITIES (Tables)

3 Months Ended

Mar. 31, 2024

LONG TERM DEBT & AVAILABLE FACILITIES

Schedule of Debt

			March 31, 2024						December 31, 2023
	Interest Rate as of March 31, 2024	Maturity Date	Carrying Amount		Unamortized Deferred Financing Fees (1)		Total Debt, Less Unamortized Deferred Financing Fees		Carrying Amount		Unamortized Deferred Financing Fees (1)		Total Debt, Less Unamortized Deferred Financing Fees
2029 Senior Notes	5.125%	April 2029	$	447.0	$	(10.7)	$	436.3	$	447.0	$	(11.1)	$	435.9
2025 Senior Notes (2)	5.375%	September 2025		115.0		(0.5)		114.5		115.0		(0.6)		114.4
Senior Credit Facility
2028 Term Loan B	8.105%	May 2028		727.2		(11.2)		716.0		728.9		(11.8)		717.1
2026 Revolving Facility (3)	Various	May 2026		—		—		—		—		—		—
2028 Refinance Term Loans (2)	13.823%	May 2028		1,045.2		(21.2)		1,024.0		1,046.5		(22.6)		1,023.9
Accounts Receivable Securitization Facility (4)	Various	November 2025		—		—		—		—		—		—
Other indebtedness	Various	Various		7.0		—		7.0		7.2		—		7.2
Total debt			$	2,341.4	$	(43.6)	$	2,297.8	$	2,344.6	$	(46.1)	$	2,298.5
Less: current portion(5)								(21.1)						(20.9)
Total long-term debt, net of unamortized deferred financing fees							$	2,276.7					$	2,277.6

(1) This caption does not include deferred financing fees related to the Company’s revolving facilities, which are included within “Deferred charges and other assets” on the condensed consolidated balance sheets.

(2) The 2025 Senior Notes were partially repaid on September 8, 2023 using the proceeds of the 2028 Refinance Term Loans.

(3) As of March 31, 2024, under the 2026 Revolving Facility, the Company had a capacity of $375.0 million and $20.8

million outstanding letters of credit. As of March 31, 2024, the Company had funds available for borrowing of $101.7 million (net of the applicable $10.8 million outstanding letters of credit as defined in the secured credit agreement), which reflects the borrowing limit imposed by the springing covenant. The springing covenant applies when 30% or more of the 2026 Revolving Facility’s capacity is drawn which then requires the Company to meet a first lien net leverage ratio (as defined in the secured credit agreement) not to exceed 3.50x at the end of each financial quarter. As of March 31, 2024, the first lien net leverage ratio was 6.96x and the outstanding borrowings did not exceed the 30% threshold. Additionally, the Company is required to pay a quarterly commitment fee in respect of any unused commitments under this facility equal to 0.375% per annum.

(4) As of March 31, 2024, this facility had a borrowing capacity of $150.0 million, and the Company had approximately $150.0 million of accounts receivable available to support this facility, based on the pool of eligible accounts receivable.

(5) The current portion of long-term debt was primarily related to $18.3 million of the scheduled future principal payments on both the 2028 Term Loan B and the 2028 Refinance Term Loans as of March 31, 2024 and December 31, 2023.

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FINANCIAL INSTRUMENTS AND DERIVATIVES (Tables)

3 Months Ended

Mar. 31, 2024

FINANCIAL INSTRUMENTS AND DERIVATIVES

Notional Amounts of Most Significant Net Foreign Exchange Hedge Positions Outstanding

Buy / (Sell)	March 31, 2024
Euro	$	(276.6)
Chinese Yuan	$	(21.7)
South Korean Won	$	(17.9)
Swiss Franc	$	12.9
Indonesian Rupiah	$	(5.9)

Schedule of Effect of Derivative Instruments on Statements of Operations

	Location and Amount of Gain (Loss) Recognized in Statements of Operations
	Three Months Ended				Three Months Ended
	March 31, 2024				March 31, 2023
	Cost of sales		Other (expense) income, net		Cost of sales		Other (expense) income, net
Total amount of income and (expense) line items presented in the statements of operations in which the effects of derivative instruments are recorded	$	(843.4)	$	(3.8)	$	(959.1)	$	2.9
The effects of cash flow hedge instruments:
Commodity cash flow hedges
Amount of loss reclassified from AOCI into income	$	(4.8)	$	—	$	(6.4)	$	—
The effects of derivatives not designated as hedge instruments:
Foreign exchange forward contracts
Amount of gain (loss) recognized in income	$	—	$	6.5	$	—	$	(7.8)
Commodity economic hedges
Amount of loss recognized in income	$	(1.6)	$	—	$	(12.4)	$	—

Schedule of Effect of Hedges on AOCI

`	Gain (Loss) Recognized in AOCI on Balance Sheet
	Three Months Ended
	March 31,
	2024		2023
Designated as Cash Flow Hedges
Commodity cash flow hedges	$	2.7	$	(9.9)
Total	$	2.7	$	(9.9)

	Gain (Loss) Recognized in Other expense (income), net in Statement of Operations
	Three Months Ended
	March 31,
	2024		2023
Settlements and changes in the fair value of forward contracts (not designated as hedges)	$	6.5	$	(7.8)
Remeasurement of foreign currency-denominated assets and liabilities		(8.6)		10.5
Total	$	(2.1)	$	2.7

Schedule of Gross and Net Unrealized Gains and Losses and Balance Sheet Classification

	March 31, 2024
	Foreign
	Exchange		Commodity		Commodity
Balance Sheet	Forward		Economic		Cash Flow
Classification	Contracts		Hedges		Hedges		Total
Asset Derivatives:
Accounts receivable, net of allowance	$	1.2	$	—	$	—	$	1.2
Gross derivative asset position		1.2		—		—		1.2
Less: Counterparty netting		(0.5)		—		—		(0.5)
Net derivative asset position	$	0.7	$	—	$	—	$	0.7
Liability Derivatives:
Accounts payable	$	(0.7)	$	(6.0)	$	(9.6)	$	(16.3)
Gross derivative liability position		(0.7)		(6.0)		(9.6)		(16.3)
Less: Counterparty netting		0.5		—		—		0.5
Net derivative liability position	$	(0.2)	$	(6.0)	$	(9.6)	$	(15.8)
Total net derivative position	$	0.5	$	(6.0)	$	(9.6)	$	(15.1)

	December 31, 2023
	Foreign
	Exchange		Commodity		Commodity
Balance Sheet	Forward		Economic		Cash Flow
Classification	Contracts		Hedges		Hedges		Total
Asset Derivatives:
Accounts receivable, net of allowance	$	0.3	$	—	$	—	$	0.3
Gross derivative asset position		0.3		—		—		0.3
Less: Counterparty netting		(0.3)		—		—		(0.3)
Net derivative asset position	$	—	$	—	$	—	$	—
Liability Derivatives:
Accounts payable	$	(4.8)	$	(7.2)	$	(13.7)	$	(25.7)
Other noncurrent obligations		—		(0.9)		(0.7)		(1.6)
Gross derivative liability position		(4.8)		(8.1)		(14.4)		(27.3)
Less: Counterparty netting		0.3		—		—		0.3
Net derivative liability position	$	(4.5)	$	(8.1)	$	(14.4)	$	(27.0)
Total net derivative position	$	(4.5)	$	(8.1)	$	(14.4)	$	(27.0)

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FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2024

FAIR VALUE MEASUREMENTS

Schedule of Assets and Liabilities at Fair Value on Recurring Basis

	March 31, 2024
	Quoted Prices in Active Markets for Identical Items		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets (Liabilities) at Fair Value	(Level 1)		(Level 2)		(Level 3)		Total
Foreign exchange forward contracts—Assets	$	—	$	0.7	$	—	$	0.7
Foreign exchange forward contracts—(Liabilities)		—		(0.2)		—		(0.2)
Commodity economic hedges—(Liabilities)		—		(6.0)		—		(6.0)
Commodity cash flow hedges—(Liabilities)		—		(9.6)		—		(9.6)
Total fair value	$	—	$	(15.1)	$	—	$	(15.1)

	December 31, 2023
	Quoted Prices in Active Markets for Identical Items		Significant Other Observable Inputs		Significant Unobservable Inputs
Liabilities at Fair Value	(Level 1)		(Level 2)		(Level 3)		Total
Foreign exchange forward contracts—(Liabilities)	$	—	$	(4.5)	$	—	$	(4.5)
Commodity economic hedges—(Liabilities)		—		(8.1)		—		(8.1)
Commodity cash flow hedges—(Liabilities)		—		(14.4)		—		(14.4)
Total fair value	$	—	$	(27.0)	$	—	$	(27.0)

Estimated Fair Value of Outstanding Debt Not Carried at Fair Value

	As of		As of
	March 31, 2024		December 31, 2023
2029 Senior Notes	$	146.7	$	180.4
2025 Senior Notes		92.8		98.5
2028 Term Loan B		539.9		564.9
2028 Refinance Term Loans		1,091.7		1,087.1
Total fair value	$	1,871.1	$	1,930.9

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COMMITMENTS AND CONTINGENCIES (Tables)

3 Months Ended

Mar. 31, 2024

COMMITMENTS AND CONTINGENCIES

Schedule of asset retirement cost

Change in asset retirement obligation
Balance at December 31, 2023	$	20.2
Obligations incurred and adjustments to estimated obligations		—
Settlements		(1.8)
Accretion expense		0.2
Currency translation adjustment		(0.5)
Balance at March 31, 2024	$	18.1

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PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Tables)

3 Months Ended

Mar. 31, 2024

PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS

Schedule of Net Periodic Benefit Costs

	Three Months Ended				Three Months Ended
	March 31,				March 31,
	Non-U.S. Defined Benefit Pension Plans				U.S. Defined Benefit Pension
	2024		2023		2024		2023
Net periodic benefit cost
Service cost	$	2.1	$	2.0	$	0.1	$	0.1
Interest cost		2.4		1.7		0.2		0.2
Expected return on plan assets		(1.0)		(0.2)		(0.2)		(0.1)
Amortization of prior service credit		(0.1)		(0.1)		—		—
Amortization of net gain		(0.3)		(0.8)		—		—
Net periodic benefit cost	$	3.1	$	2.6	$	0.1	$	0.2

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SHARE-BASED COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2024

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Share-Based Compensation Expense and Unrecognized Compensation Cost

					As of
	Three Months Ended				March 31, 2024
	March 31,				Unrecognized		Weighted
	2024		2023		Compensation Cost		Average Years
RSUs	$	2.4	$	4.8	$	6.5	1.4
Options		0.8		2.6		1.1	1.2
PSUs		0.6		0.8		4.8	2.0
Restricted Cash Units ("RCUs")		2.1		—		3.0 (1)	1.9
Total share-based compensation expense	$	5.9	$	8.2

(1) Unrecognized Compensation Cost related to RCU awards as of March 31, 2024 is calculated using the stock price as of March 31, 2024.

Summary of Awards Granted and Weighted Average Grant-Date Fair Value

	Three Months Ended
	March 31, 2024
	Awards Granted		Weighted Average Grant Date Fair Value per Award
RSUs		646,972	$	4.38
Options		319,407		2.48
PSUs		575,475		2.81
RCUs		1,074,119		4.85

Employee Stock Option

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Weighted-average Assumptions

	Three Months Ended
	March 31, 2024
Expected term (in years)	5.50
Expected volatility	64.12	%
Risk-free interest rate	4.28	%
Dividend yield	0.73	%

Performance Share Units

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Weighted-average Assumptions

		Three Months Ended
		March 31, 2024
Expected term (in years)		3.00
Expected volatility		65.40	%
Risk-free interest rate		4.40	%
Share price	$	4.39

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SEGMENTS AND GEOGRAPHIC INFORMATION (Tables)

3 Months Ended

Mar. 31, 2024

SEGMENTS AND GEOGRAPHIC INFORMATION

Reconciliation of Segment Reporting to Consolidated

	Engineered		Latex		Plastics				Americas		Total Segment
Three Months Ended (1)	Materials		Binders		Solutions		Polystyrene		Styrenics		Adjusted EBITDA
March 31, 2024	$	4.3	$	25.7	$	22.7	$	12.6	$	6.1	$	71.4
March 31, 2023	$	(11.7)	$	24.0	$	23.6	$	8.9	$	17.6	$	62.4

(1) The Company’s primary measure of segment operating performance is Adjusted EBITDA, which is defined as income from continuing operations before interest expense, net; provision for income taxes; depreciation and amortization expense; loss on extinguishment of long-term debt; asset impairment charges; gains or losses on the dispositions of businesses and assets; restructuring charges; acquisition related costs and benefits and other items. Segment Adjusted EBITDA is a key metric that is used by management to evaluate business performance in comparison to budgets, forecasts, and prior year financial results, providing a measure that management believes reflects core operating performance by removing the impact of transactions and events that would not be considered a part of core operations. Other companies in the industry may define segment Adjusted EBITDA differently than the Company, and as a result, it may be difficult to use segment Adjusted EBITDA, or similarly named financial measures, that other companies may use to compare the performance of those companies to the Company’s segment performance.

Reconciliation of IBT to Adjusted EBITDA

	Three Months Ended
	March 31,
	2024		2023
Loss before income taxes	$	(70.1)	$	(65.6)
Interest expense, net		63.0		38.3
Depreciation and amortization		45.0		56.0
Corporate Unallocated(2)		26.4		26.1
Adjusted EBITDA Addbacks(3)		7.1		7.6
Segment Adjusted EBITDA	$	71.4	$	62.4

(2) Corporate unallocated includes corporate overhead costs and certain other income and expenses.

(3) Adjusted EBITDA addbacks for the three months ended March 31, 2024 and 2023 are as follows:

	Three Months Ended
	March 31,
	2024		2023
Net gain on disposition of businesses and assets	$	(3.6)	$	—
Restructuring and other charges (Note 4)		9.4		3.7
Asset impairment charges or write-offs (Note 12)		—		0.3
Other items (a)		1.3		3.6
Total Adjusted EBITDA Addbacks	$	7.1	$	7.6

(a) Other items for the three months ended March 31, 2024 and 2023 primarily relate to costs incurred in conjunction with certain of the Company’s strategic initiatives. Other items for the three months ended March 31, 2023 also relate to our transition to a new enterprise resource planning system.

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ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)

3 Months Ended

Mar. 31, 2024

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

Components of AOCI, Net of Income Taxes

	Cumulative		Pension & Other
	Translation		Postretirement Benefit			Cash Flow
Three Months Ended March 31, 2024 and 2023	Adjustments		Plans, Net			Hedges, Net	Total
Balance as of December 31, 2023	$	(141.9)	$	17.1	$	(4.8)	$	(129.6)
Other comprehensive income (loss)		(11.8)		—		0.1		(11.7)
Amounts reclassified from AOCI to net income(1)		—		(0.4)		4.3		3.9
Balance as of March 31, 2024	$	(153.7)	$	16.7	$	(0.4)	$	(137.4)
Balance as of December 31, 2022	$	(151.2)	$	29.0	$	(9.1)	$	(131.3)
Other comprehensive income (loss)		10.5		—		(13.2)		(2.7)
Amounts reclassified from AOCI to net income (1)		—		0.3		5.8		6.1
Balance as of March 31, 2023	$	(140.7)	$	29.3	$	(16.5)	$	(127.9)

(1) The following is a summary of amounts reclassified from AOCI to net income (loss) for the three months ended March 31, 2024 and 2023:

Summary of amounts reclassified from AOCI to net income (loss)

	Three Months Ended
	March 31,				Statements of Operations
AOCI Components	2024		2023		Classification
Cash flow hedging items
Commodity cash flow hedges	$	4.8	$	6.4	Cost of sales
Total before tax		4.8		6.4
Tax effect		(0.5)		(0.6)	Provision for (benefit from) income taxes
Total, net of tax	$	4.3	$	5.8
Amortization of pension and other postretirement benefit plan items
Prior service credit	$	(0.1)	$	0.1	(a)
Net actuarial (gain) loss		(0.4)		0.3	(a)
Total before tax		(0.5)		0.4
Tax effect		0.1		(0.1)	Provision for (benefit from) income taxes
Total, net of tax	$	(0.4)	$	0.3

(a) These AOCI components are included in the computation of net periodic benefit costs (see Note 14).

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NET SALES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
NET SALES
Net sales	$ 904.0	$ 996.3

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RESTRUCTURING ACTIVITIES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	$ 7.2
Asset optimization and corporate restructuring, cost incurred to date	61.6
Restructuring Charges	$ 8.6	$ 7.7
Restructuring, Incurred Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Selling, General and Administrative Expense	Selling, General and Administrative Expense
Restructuring Reserve [Roll Forward]
Accrued charges/Balance at beginning of period	$ 16.7
Expenses	8.0
Deductions	(12.6)
Accrued charges/Balance at end of period	12.1
Land, buildings and equipment for sale in Bronderslev, Denmark and in Belen, Mexico
Restructuring Cost and Reserve [Line Items]
Cash Consideration	4.7
Proceed form sale of property	2.9
Gain on sale of property held-for-sale	3.6
Transformational Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative life-to-date charges	6.7
Accelerated Depreciation | Asset restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 4.0
Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.5
Restructuring Reserve [Roll Forward]
Accrued charges/Balance at beginning of period	16.7
Expenses	(0.4)
Deductions	(4.2)
Accrued charges/Balance at end of period	12.1
Employee termination benefits | Corporate Restructuring Program
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	1.2
Asset optimization and corporate restructuring, cost incurred to date	10.0
Employee termination benefits | Transformational Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative life-to-date charges	6.7
Employee termination benefits | Asset restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	(0.6)	(0.6)
Contract terminations
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	4.8
Restructuring Reserve [Roll Forward]
Expenses	5.5
Deductions	(5.5)
Contract terminations | Asset restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1.7	2.5
Expected restructuring charges	10.5
Decommissioning and other
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	16.2
Restructuring Charges	2.9
Restructuring Reserve [Roll Forward]
Expenses	2.9
Deductions	(2.9)
Decommissioning and other | Asset restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.3	1.8
Expected restructuring charges	0.5
Plastics Solutions | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring, cost incurred to date	19.6
Restructuring Charges		0.9
Cumulative life-to-date charges	27.4
Plastics Solutions | Accelerated Depreciation | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.2
Plastics Solutions | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	(0.7)
Asset optimization and corporate restructuring, cost incurred to date	4.7
Restructuring Charges		(0.2)
Cumulative life-to-date charges	3.7
Plastics Solutions | Contract terminations
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	3.8
Asset optimization and corporate restructuring, cost incurred to date	6.3
Restructuring Charges	1.7	2.5
Cumulative life-to-date charges	10.0
Plastics Solutions | Contract terminations | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.6
Plastics Solutions | Decommissioning and other
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	1.8
Asset optimization and corporate restructuring, cost incurred to date	6.8
Restructuring Charges	0.3	0.5
Cumulative life-to-date charges	4.5
Plastics Solutions | Decommissioning and other | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.1
Plastic Solution | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Cumulative life-to-date charges	1.4
Plastic Solution | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	(0.6)	(0.4)
Cumulative life-to-date charges	2.4
Plastic Solution | Decommissioning and other
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1.9	0.7
Feedstocks | Contract terminations
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	3.8
Engineered Materials
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1.4	7.7
Cumulative life-to-date charges	61.6
Engineered Materials | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring, cost incurred to date	9.3
Restructuring Charges		3.1
Cumulative life-to-date charges	6.3
Engineered Materials | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring, cost incurred to date	1.2
Cumulative life-to-date charges	2.7
Engineered Materials | Decommissioning and other
Restructuring Cost and Reserve [Line Items]
Asset optimization and corporate restructuring subtotal	1.1
Asset optimization and corporate restructuring, cost incurred to date	3.7
Restructuring Charges		0.6
Cumulative life-to-date charges	$ 1.3
Latex Binders | Accelerated Depreciation | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.1
Latex Binders | Contract terminations | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.4
Latex Binders | Decommissioning and other | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.1
Polystyrene | Accelerated Depreciation | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.6
Polystyrene | Employee termination benefits | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		(0.1)
Polystyrene | Contract terminations | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		1.5
Polystyrene | Decommissioning and other | Revision of Prior Period
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 0.3

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INCOME TAXES - Effective Tax Rate (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Taxes [Line Items]
Effective income tax rate	(7.70%)	25.40%
Provision for income taxes	$ 5.4	$ (16.7)
China
Income Taxes [Line Items]
Deferred tax assets	$ 13.5

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EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings:
Net loss	$ (75.5)	$ (48.9)
Shares:
Weighted average ordinary shares outstanding	35.3	35.0
Diluted weighted average ordinary shares outstanding	35.3	35.0
Loss per share:
Loss per share-basic	$ (2.14)	$ (1.40)
Loss per share-diluted	$ (2.14)	$ (1.40)

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INVENTORIES (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
INVENTORIES
Finished goods	$ 190.2		$ 162.4
Raw materials and semi-finished goods	199.4		200.9
Supplies	41.6		41.4
Total	$ 431.2	$ 404.7	$ 404.7

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INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Summarized Financial Information, Net Income
Gross profit	$ 60.6	$ 37.2
Net income	(75.5)	(48.9)
AmSty
Summarized Financial Information, Net Income
Sales	386.0	443.3
Gross profit	11.6	52.9
Net income	$ (3.7)	$ 37.8

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INVESTMENTS IN UNCONSOLIDATED AFFILIATES - Americas Styrenics (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Investments in Unconsolidated Affiliates
Investments in unconsolidated affiliate	$ 258.4		$ 252.2
AmSty
Investments in Unconsolidated Affiliates
Investments in unconsolidated affiliate	258.4		252.2
Investment in unconsolidated affiliates-difference between carrying amount and underlying equity	$ 12.6		$ 4.8
Percentage of ownership underlying net assets	50.00%		50.00%
Amortized weighted average remaining useful life	2.6
Dividends received from operating activities	$ 0.0	$ 20.0

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GOODWILL (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Goodwill [Roll Forward]
Beginning Balance	$ 63.8
Foreign currency impact	(1.5)
Ending Balance	62.3
Engineered Materials
Goodwill [Roll Forward]
Accumulated impairment loss	(646.1)	$ (646.1)
Latex Binders
Goodwill [Roll Forward]
Beginning Balance	15.4
Foreign currency impact	(0.4)
Ending Balance	15.0
Plastics Solutions
Goodwill [Roll Forward]
Beginning Balance	44.0
Foreign currency impact	(1.0)
Ending Balance	43.0
Polystyrene
Goodwill [Roll Forward]
Beginning Balance	4.4
Foreign currency impact	(0.1)
Ending Balance	$ 4.3

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LONG TERM DEBT & AVAILABLE FACILITIES - Schedule of Debt (Details) - USD ($) $ in Millions			3 Months Ended
	Mar. 28, 2024	Sep. 08, 2023	Mar. 31, 2024	Nov. 18, 2024	Dec. 31, 2023
Debt Instruments
Carrying amount			$ 2,341.4		$ 2,344.6
Unamortized deferred financing fees			(43.6)		(46.1)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent			2,297.8		2,298.5
Less: current portion			(21.1)		(20.9)
Total long-term debt, net of unamortized deferred financing fees			2,276.7		2,277.6
Term Loan B
Debt Instruments
Less: current portion			$ (18.3)		(18.3)
2028 Term Loan B
Debt Instruments
Interest rate at end of period (as a percent)			8.105%
Carrying amount			$ 727.2		728.9
Unamortized deferred financing fees			(11.2)		(11.8)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent			716.0		717.1
2026 Revolving Facility
Debt Instruments
Funds available for borrowings			101.7
Letters of credit, amount outstanding			20.8
Maximum borrowing amount			$ 375.0
Percentage of Revolving Facility borrowing capacity covenant trigger			30.00%
2026 Revolving Facility | Letter of Credit [Member]
Debt Instruments
Letters of credit, amount outstanding			$ 10.8
Commitment fee (as a percent)			0.375%
Percentage of Revolving Facility borrowing capacity covenant trigger			3.50%
Net leverage ratio			6.96
2029 Senior Notes
Debt Instruments
Interest rate			5.125%
Carrying amount			$ 447.0		447.0
Unamortized deferred financing fees			(10.7)		(11.1)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent			$ 436.3		435.9
2025 Senior Notes
Debt Instruments
Interest rate			5.375%
Carrying amount			$ 115.0		115.0
Unamortized deferred financing fees			(0.5)		(0.6)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent			$ 114.5		114.4
2028 Refinance Term Loans
Debt Instruments
Interest rate at end of period (as a percent)			13.823%
Carrying amount			$ 1,045.2		1,046.5
Unamortized deferred financing fees			(21.2)		(22.6)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent			1,024.0		1,023.9
Funds available for borrowings			251.7
Liquidity balance needed for Refinance Agreement		$ 100.0
Liquidity balance			415.6
Cash and cash equivalents			163.8
Accounts Receivable Securitization Facility
Debt Instruments
Interest rate at end of period (as a percent)	1.65%
Carrying amount			0.0		0.0
Unamortized deferred financing fees			0.0		0.0
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent			0.0		0.0
Funds available for borrowings			150.0
Commitment fee (as a percent)	0.80%
Maximum borrowing amount	$ 150.0		150.0
Amount of minimum liquidity to be maintained	250.0
Debt issuance costs	$ 0.5
Accounts Receivable Securitization Facility | Subsequent Event
Debt Instruments
Interest rate at end of period (as a percent)				3.50%
Other Indebtedness
Debt Instruments
Carrying amount			7.0		7.2
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent			$ 7.0		$ 7.2

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FINANCIAL INSTRUMENTS AND DERIVATIVES (Details) MWh in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) MWh item
Foreign exchange forward contracts
Derivative Instruments
Derivative term	2 months
Foreign exchange forward contracts | Not Designated as Hedging Instruments
Derivative Instruments
Derivative, Notional Amount, Buy / (Sell)	$ 347.5
Foreign exchange forward contracts | Designated as Hedging Instrument
Derivative Instruments
Number of subsidiaries participating | item	1
Foreign exchange forward contracts | Designated as Hedging Instrument | Cash Flow Hedges
Derivative Instruments
Amount hedged	$ 0.0
Commodity Contract
Derivative Instruments
Derivative term	12 months
Number of megawatt hours of natural gas purchases | MWh	339
Commodity Contract | Cash Flow Hedges
Derivative Instruments
Derivative term	9 months
Number of megawatt hours of natural gas purchases | MWh	462
Euro | Foreign exchange forward contracts | (Sell) | Not Designated as Hedging Instruments
Derivative Instruments
Derivative, Notional Amount, Buy / (Sell)	$ 276.6
Chinese Yuan | Foreign exchange forward contracts | (Sell) | Not Designated as Hedging Instruments
Derivative Instruments
Derivative, Notional Amount, Buy / (Sell)	21.7
South Korean Won | Foreign exchange forward contracts | (Sell) | Not Designated as Hedging Instruments
Derivative Instruments
Derivative, Notional Amount, Buy / (Sell)	17.9
Swiss Franc | Foreign exchange forward contracts | Buy | Not Designated as Hedging Instruments
Derivative Instruments
Derivative, Notional Amount, Buy / (Sell)	12.9
Indonesian Rupiah | Foreign exchange forward contracts | (Sell) | Not Designated as Hedging Instruments
Derivative Instruments
Derivative, Notional Amount, Buy / (Sell)	$ 5.9

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FINANCIAL INSTRUMENTS AND DERIVATIVES - Income Statements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Cost of Sales	$ (843.4)	$ (959.1)
Other expense (income), net	(3.8)	2.9
Cost of Sales
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain recognized in income, not designated	(1.6)	(12.4)
Foreign exchange forward contracts | Not Designated as Hedging Instruments | Other expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain recognized in income, not designated	6.5	(7.8)
Commodity Contract | Cash Flow Hedges | Cost of Sales
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain (loss) reclassified from AOCI into income	$ (4.8)	$ (6.4)

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FINANCIAL INSTRUMENTS AND DERIVATIVES - Effect on AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Derivative Instruments
Gain (Loss) Recognized in AOCI, Cash flow hedges	$ 2.7	$ (9.9)
Commodity Contract
Derivative Instruments
Gain (Loss) Recognized in AOCI, Cash flow hedges	$ 2.7	$ (9.9)

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FINANCIAL INSTRUMENTS AND DERIVATIVES - Gains and Losses in Other expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative, Gain (Loss) on Derivative, Net, Total	$ (2.1)	$ 2.7
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Reclassification expected during next 12 months	$ 9.6
Other expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Foreign exchange transaction gains (losses)	(8.6)	$ 10.5
Foreign exchange forward contracts | Not Designated as Hedging Instruments | Other expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain recognized in income, not designated	$ 6.5	$ (7.8)

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FINANCIAL INSTRUMENTS AND DERIVATIVES - Financial Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Derivatives, Financial Assets and Liabilities
Assets at fair value	$ 1.2	$ 0.3
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Accounts and Other Receivables, Net, Current	Accounts and Other Receivables, Net, Current
Gross derivative asset position	$ 1.2	$ 0.3
Less: Counterparty netting	(0.5)	(0.3)
Net derivative asset position	0.7
Liabilities at fair value	$ (16.3)	$ (25.7)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Gross derivative liability position	$ (16.3)	$ (27.3)
Less: Counterparty netting	0.5	0.3
Net derivative liability position	(15.8)	(27.0)
Total net derivative position	(15.1)	(27.0)
Other noncurrent obligations.
Derivatives, Financial Assets and Liabilities
Liabilities at fair value		$ (1.6)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Other Liabilities, Noncurrent
Foreign exchange forward contracts | Not Designated as Hedging Instruments
Derivatives, Financial Assets and Liabilities
Assets at fair value	$ 1.2	$ 0.3
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Accounts and Other Receivables, Net, Current
Gross derivative asset position	$ 1.2	0.3
Less: Counterparty netting	(0.5)	(0.3)
Net derivative asset position	0.7
Liabilities at fair value	$ (0.7)	$ (4.8)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Gross derivative liability position	$ (0.7)	$ (4.8)
Less: Counterparty netting	0.5	0.3
Net derivative liability position	(0.2)	(4.5)
Total net derivative position	0.5	(4.5)
Commodity Contract
Derivatives, Financial Assets and Liabilities
Liabilities at fair value	(6.0)	(7.2)
Gross derivative liability position	(6.0)	(8.1)
Net derivative liability position	(6.0)	(8.1)
Total net derivative position	$ (6.0)	(8.1)
Commodity Contract | Other noncurrent obligations.
Derivatives, Financial Assets and Liabilities
Liabilities at fair value		$ (0.9)
Commodity Contract | Not Designated as Hedging Instruments
Derivatives, Financial Assets and Liabilities
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Commodity Contract | Cash Flow Hedges
Derivatives, Financial Assets and Liabilities
Liabilities at fair value	$ (9.6)	$ (13.7)
Gross derivative liability position	(9.6)	(14.4)
Net derivative liability position	(9.6)	(14.4)
Total net derivative position	$ (9.6)	(14.4)
Commodity Contract | Cash Flow Hedges | Other noncurrent obligations.
Derivatives, Financial Assets and Liabilities
Liabilities at fair value		$ (0.7)
Commodity Contract | Cash Flow Hedges | Not Designated as Hedging Instruments
Derivatives, Financial Assets and Liabilities
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current

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FAIR VALUE MEASUREMENTS - Assets and Liabilities at Fair Value, Recurring (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value Measurements
Assets at fair value	$ 1.2	$ 0.3
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Accounts and Other Receivables, Net, Current	Accounts and Other Receivables, Net, Current
Liabilities at fair value	$ (16.3)	$ (25.7)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Total net derivative position	$ (15.1)	$ (27.0)
Property Plant And Equipment At Fair Value | Boehlen Location
Fair Value Measurements
Assets at fair value, nonrecurring	3.2	3.2
Commodity Contract
Fair Value Measurements
Liabilities at fair value	(6.0)	(7.2)
Total net derivative position	(6.0)	(8.1)
Commodity Contract | Cash Flow Hedges
Fair Value Measurements
Liabilities at fair value	(9.6)	(13.7)
Total net derivative position	(9.6)	(14.4)
Not Designated as Hedging Instruments | Foreign exchange forward contracts
Fair Value Measurements
Assets at fair value	$ 1.2	0.3
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Accounts and Other Receivables, Net, Current
Liabilities at fair value	$ (0.7)	$ (4.8)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Total net derivative position	$ 0.5	$ (4.5)
Not Designated as Hedging Instruments | Commodity Contract
Fair Value Measurements
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Not Designated as Hedging Instruments | Commodity Contract | Cash Flow Hedges
Fair Value Measurements
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Recurring
Fair Value Measurements
Total net derivative position	$ (15.1)	$ (27.0)
Recurring | Level 2
Fair Value Measurements
Total net derivative position	(15.1)	(27.0)
Recurring | Not Designated as Hedging Instruments | Foreign exchange forward contracts
Fair Value Measurements
Assets at fair value	0.7
Liabilities at fair value	(0.2)	(4.5)
Recurring | Not Designated as Hedging Instruments | Commodity Contract
Fair Value Measurements
Liabilities at fair value	(6.0)	(8.1)
Recurring | Not Designated as Hedging Instruments | Commodity Contract | Cash Flow Hedges
Fair Value Measurements
Liabilities at fair value	(9.6)	(14.4)
Recurring | Not Designated as Hedging Instruments | Level 2 | Foreign exchange forward contracts
Fair Value Measurements
Assets at fair value	0.7
Liabilities at fair value	(0.2)	(4.5)
Recurring | Not Designated as Hedging Instruments | Level 2 | Commodity Contract
Fair Value Measurements
Liabilities at fair value	(6.0)	(8.1)
Recurring | Not Designated as Hedging Instruments | Level 2 | Commodity Contract | Cash Flow Hedges
Fair Value Measurements
Liabilities at fair value	$ (9.6)	(14.4)
Nonrecurring
Fair Value Measurements
Assets at fair value, nonrecurring		0.0
Liabilities at fair value, nonrecurring		$ 0.0

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FAIR VALUE MEASUREMENTS - Items not at Fair Value (Details) - Level 2 - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value of Debt Instruments
Total fair value of long term debt	$ 1,871.1	$ 1,930.9
2029 Senior Notes
Fair Value of Debt Instruments
Total fair value of long term debt	146.7	180.4
2025 Senior Notes
Fair Value of Debt Instruments
Total fair value of long term debt	92.8	98.5
2028 Term Loan B
Fair Value of Debt Instruments
Total fair value of long term debt	539.9	564.9
2028 Refinance Term Loans
Fair Value of Debt Instruments
Total fair value of long term debt	$ 1,091.7	$ 1,087.1

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COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Apr. 30, 2024 USD ($)	Mar. 31, 2024 USD ($) item	Dec. 31, 2023 USD ($)
Loss Contingencies [Line Items]
Accrued obligations for environmental remediation and restoration costs		$ 1.3	$ 1.3
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]		Accrued Liabilities and Other Liabilities, Other Liabilities, Noncurrent	Accrued Liabilities and Other Liabilities, Other Liabilities, Noncurrent
Environmental claims asserted | item		0
Subsequent Event [Member]
Loss Contingencies [Line Items]
Accrued obligations for environmental remediation and restoration costs	$ 2.7

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COMMITMENTS AND CONTINGENCIES - Purchase Commitments (Details)	3 Months Ended
	Mar. 31, 2024
Maximum
Loss Contingencies [Line Items]
Purchase commitment period	4 years
Minimum
Loss Contingencies [Line Items]
Purchase commitment period	1 year

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COMMITMENTS AND CONTINGENCIES - Change in asset retirement obligation (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)
Change in asset retirement obligation
Balance at December 31, 2023	$ 20.2
Settlements	(1.8)
Accretion expense	0.2
Currency translation adjustment	(0.5)
Balance at March 31, 2024	$ 18.1

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COMMITMENTS AND CONTINGENCIES - Additional Information (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	May 21, 2021
Loss Contingencies [Line Items]
Current portion	$ 8.8	$ 10.7
Long-term portion	$ 9.3	$ 9.5
Pending Litigation | Synthos
Loss Contingencies [Line Items]
Current portion			$ 491.0

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PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS - Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
U.S. Plans And Non-U.S. Plans
Net periodic benefit cost
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Pension Plans | Non-U.S. Plans
Net periodic benefit cost
Service cost	$ 2.1	$ 2.0
Interest cost	2.4	1.7
Expected return on plan assets	(1.0)	(0.2)
Amortization of prior service credit	(0.1)	(0.1)
Amortization of net gain	(0.3)	(0.8)
Net periodic benefit cost	3.1	2.6
Defined Benefit Pension Plans | U.S. Plans
Net periodic benefit cost
Service cost	0.1	0.1
Interest cost	0.2	0.2
Expected return on plan assets	(0.2)	(0.1)
Net periodic benefit cost	0.1	0.2
Other Postretirement Benefit Plans | Maximum
Net periodic benefit cost
Net periodic benefit cost	$ 0.1	$ 0.1

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PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS - Net Amounts Recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Net amounts recognized in the balance sheets at December 31
Benefit obligations	$ 192.3	$ 197.0
Cash contributions and benefit payments to unfunded plans	2.5
Additional cash contributions, including benefit payments to unfunded plans	$ 6.7

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SHARE-BASED COMPENSATION - Summary of Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 5.9	$ 8.2
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	2.4	4.8
Unrecognized compensation cost	$ 6.5
Weighted-average period of recognition	1 year 4 months 24 days
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 0.8	2.6
Unrecognized compensation cost, options	$ 1.1
Weighted-average period of recognition	1 year 2 months 12 days
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 0.6	$ 0.8
Unrecognized compensation cost	$ 4.8
Weighted-average period of recognition	2 years
Restricted Cash Units (RCUs)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 2.1
Unrecognized compensation cost	$ 3.0
Weighted-average period of recognition	1 year 10 months 24 days

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SHARE-BASED COMPENSATION - RSU, Options, PSUs and RCUs (Details)	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Restricted Stock Units
Other-than-Options, Shares Activity
Granted, Shares	646,972
Other-than-Options, FV Activity
Granted, Weighted-Average Grant Date Fair Value per Share | $ / shares	$ 4.38
Employee Stock Option
Options Outstanding Roll Forward
Granted, Options	319,407
Fair Value Assumptions
Expected term (in years)	5 years 6 months
Expected volatility	64.12%
Risk-free interest rate	4.28%
Dividend yield	0.73%
Options granted, Weighted average grant date fair value | $ / shares	$ 2.48
Performance Share Units
Fair Value Assumptions
Expected term (in years)	3 years
Expected volatility	65.40%
Risk-free interest rate	4.40%
Share Price | $ / shares	$ 4.39
Other-than-Options, Shares Activity
Granted, Shares	575,475
Other-than-Options, FV Activity
Granted, Weighted-Average Grant Date Fair Value per Share | $ / shares	$ 2.81
RCUs
Fair Value Assumptions
Share awards, vesting period	3 years
Other-than-Options, Shares Activity
Granted, Shares	1,074,119
Vested, Shares	0
Forfeited, Shares	0
Other-than-Options, FV Activity
Granted, Weighted-Average Grant Date Fair Value per Share | $ / shares	$ 4.85

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SEGMENTS AND GEOGRAPHIC INFORMATION - Reconciliation of Segment Reporting to Consolidated (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)	Dec. 31, 2023
Segment Reporting Information [Line Items]
Number of operating segments | segment	5
Total Segment Adjusted EBITDA	$ 71.4	$ 62.4
Engineered Materials
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	4.3	(11.7)
Latex Binders
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	25.7	24.0
Plastics Solutions
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	22.7	23.6
Polystyrene
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	12.6	8.9
Americas Styrenics
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	$ 6.1	$ 17.6
AmSty
Segment Reporting Information [Line Items]
Percentage of ownership underlying net assets	50.00%		50.00%
AmSty | Americas Styrenics
Segment Reporting Information [Line Items]
Percentage of ownership underlying net assets	50.00%

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SEGMENTS AND GEOGRAPHIC INFORMATION - Reconciliation of Net Income to Segment Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Loss before income taxes	$ (70.1)	$ (65.6)
Interest expense, net	(63.0)	(38.3)
Depreciation and amortization	45.0	56.0
Corporate Unallocated	26.4	26.1
Adjusted EBITDA Addbacks	7.1	7.6
Total Segment Adjusted EBITDA	71.4	62.4
Net gain on disposition of businesses and assets	(3.6)
Restructuring and other charges (Note 4)	9.4	3.7
Asset impairment charges or write-offs (Note 12)		0.3
Other items	1.3	3.6
Corporate Unallocated
Segment Reporting Information [Line Items]
Interest expense, net	$ 63.0	$ 38.3

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ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Components (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	$ (268.0)	$ 420.3
Balance at end of period	(348.0)	376.2
Cumulative Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(141.9)	(151.2)
Other comprehensive income (loss)	(11.8)	10.5
Balance at end of period	(153.7)	(140.7)
Pension & Other Postretirement Benefit Plans, Net
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	17.1	29.0
Amounts reclassified from AOCI to net income	(0.4)	0.3
Balance at end of period	16.7	29.3
Cash Flow Hedges, Net
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(4.8)	(9.1)
Other comprehensive income (loss)	0.1	(13.2)
Amounts reclassified from AOCI to net income	4.3	5.8
Balance at end of period	(0.4)	(16.5)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(129.6)	(131.3)
Other comprehensive income (loss)	(11.7)	(2.7)
Amounts reclassified from AOCI to net income	3.9	6.1
Balance at end of period	$ (137.4)	$ (127.9)

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ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Reclassification (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	$ 843.4	$ 959.1
Income before income taxes	70.1	65.6
Provision for income taxes	5.4	(16.7)
Net income	75.5	48.9
Pension & Other Postretirement Benefit Plans, Net | Reclassified from AOCI to net income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(0.5)	0.4
Provision for income taxes	0.1	(0.1)
Net income	$ (0.4)	$ 0.3
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] | Reclassified from AOCI to net income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credit	$ (0.1)	$ 0.1
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] | Reclassified from AOCI to net income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net actuarial loss	$ (0.4)	$ 0.3
Cash Flow Hedges, Net | Reclassified from AOCI to net income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	4.8	6.4
Provision for income taxes	(0.5)	(0.6)
Net income	4.3	5.8
Cash Flow Hedges, Net | Reclassified from AOCI to net income (loss) | Commodity Contract
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	$ 4.8	$ 6.4

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Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (75.5)	$ (48.9)

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Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Rule10b51ArrModified [Flag]	false
NonRule10b51ArrModified [Flag]	false