First Quarter 2018 Financial Results May 2, 2018 ™ Trademark of Trinseo S.A. or its affiliates

Introductions & Disclosure Rules Introductions • • • Chris Pappas, President & CEO Barry Niziolek, Executive Vice President & CFO David Stasse, Vice President, Treasury & Investor Relations Disclosure Rules Cautionary Note on Forward-Looking Statements. This presentation contains forward-looking statements including, without limitation, statements concerning plans, objectives, goals, projections, strategies, future events or performance, and underlying assumptions and other statements, which are not statements of historical facts or guarantees or assurances of future performance. Forward-looking statements may be identified by the use of words like “expect,” “anticipate,” “intend,” “forecast,” “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 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. Factors that might cause such a difference include, but are not limited to, those discussed in our Annual Report on Form 10-K, under Part I, Item 1A — “Risk Factors” and elsewhere in that report. As a result of these or other factors, our actual results may differ materially from those contemplated by the forward-looking statements. Therefore, we caution you against relying on any of these forward-looking statements. The forward-looking statements included in this presentation 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. This presentation contains financial measures that are not in accordance with generally accepted accounting principles in the US (“GAAP”) including Adjusted EBITDA, Adjusted Net Income, Adjusted EPS, Aggregate Adjusted EBITDA and Free Cash Flow. We believe these measures provide relevant and meaningful information to investors and lenders about the ongoing operating results of the Company. Such measures when referenced herein should not be viewed as an alternative to GAAP measures of performance or liquidity, as applicable. We have provided a reconciliation of these measures to the most comparable GAAP metric alongside of the respective measure or otherwise in the Appendix section of this presentation. 2

Key Points • • Net income of $120 million and Adj EBITDA* of $195 million Results exceeded prior guidance due to higher than expected styrene Q1 2018 Continued Progress Growth Targets on • ~$50MM of Adj EBITDA growth expected from 2016 to 2018 across Latex improvement in polycarbonate and $8MM of negative net timing impacts ABS plant in China, Synthetic Rubber SSBR expansion and pilot plant • Accounts Payable, Purchasing) Build process capability and drive future process improvements Services • • Assumes no impact from net timing and no impact from unplanned styrene Full Year 2018 Outlook • Outlook excludes additional unplanned styrene outages and any net timing * See Appendix for reconciliation of non-GAAP measures. 3 •Net income of $392MM to $408MM, Diluted EPS of $8.82 to $9.19 •Adj EBITDA* of $665MM to $685MM, Adj EPS* of $8.87 to $9.24 impacts beyond the unfavorable net timing impact of $7 million from the first quarter •Net income of $93MM to $101MM, Diluted EPS of $2.10 to $2.28 Q2 2018 Outlook•Adj EBITDA* of $160MM to $170MM, Adj EPS* of $2.10 to $2.28 outages beyond our current visibility for the quarter Transitioning Business•Transition out of remaining Dow-provided business services (e.g. IT, •Includes ownership and maintenance of our ERP system •On track for $100MM Adj EBITDA growth target from 2016 to 2019 Initiatives to meetBinders, Synthetic Rubber, and Performance Plastics; includes onstream – record SSBR sales volume in Q1 2018 Record Profitability in•First quarter record net income, EPS, Adj EBITDA*, and Adj EPS* margins and continued solid performance across all segments

Trinseo Q1 2018 Financial Results Adjusted EBITDA* ($MM) Net Sales & Net Income ($MM) EPS ($) Q1'18 Q1'17 Q1'18 Q1'17 $1,122 $1,104 $2.76 $195 $182 Net Sales Net Income Diluted EPS Adj EPS* Q1'18 Q1'17 (5%) (5%) 10% 1% 2% * See Appendix for reconciliation of non-GAAP measures. 4 •Record profitability in the quarter with solid fundamentals •Net income and Adjusted EBITDA* included an unfavorable net timing impact of about $7 million on a pre-tax basis •Cash from operations of $41 million and Free Cash Flow* of $10 million impacted by a $105 million working capital build due to rising styrene and butadiene prices and ahead of Q2 maintenance; $24 million of share repurchases during the quarter Vol Price FX Portfolio Total $2.71 $2.42 $2.59 $120$117

Latex Binders Net Sales ($MM) Adjusted EBITDA ($MM) Volume (MM Lbs) $37 301 $289 Q1'18 Q1'17 Q1'18 Q1'17 Q1'18 Q1'17 (9%) (9%) 6% 0% (12%) 5 •Lower volume versus prior year due to market declines in Europe and North America carpet and coated paper •Adjusted EBITDA decline year due to lower sales volume as well as prior year raw material dynamics; expected runrate ~$30MM / quarter Vol Price FX Portfolio Total $255 274 $27

Synthetic Rubber Net Sales ($MM) Adjusted EBITDA ($MM) Volume (MM Lbs) $46 179 $163 Q1'18 Q1'17 Q1'18 Q1'17 Q1'18 Q1'17 (6%) (15%) 13% (9%) 6 •Lower Adjusted EBITDA versus prior year due to favorable prior year net timing and butadiene arbitrage impacts •Record SSBR volume in Q1 as we ramp up new capacity; lower YoY sales volume driven by ESBR Vol Price FX Total $149 164 $26

Performance Plastics Net Sales ($MM) Adjusted EBITDA ($MM) $66 Volume (MM Lbs) 351 344 $403 Q1'18 Q1'17 Q1'18 Q1'17 Q1'18 Q1'17 (0%) 3% 12% 4% 20% 7 •Net sales increase vs prior year driven by higher polycarbonate pricing and the pass through of higher raw material costs •Adjusted EBITDA increase due to higher polycarbonate margins from favorable supply / demand dynamics Vol Price FX Portfolio Total $337 $52

Polystyrene Net Sales ($MM) $240 Adjusted EBITDA ($MM) Volume (MM Lbs) $14 311 308 Q1'18 Q1'17 Q1'18 Q1'17 Q1'18 Q1'17 (1%) (4%) 10% 5% 8 •Net sales increase vs prior year due mainly to favorable currency impacts •Adjusted EBITDA lower than prior year due primarily to favorable net timing in the prior year, which was partially offset by higher raw material costs Vol Price FX Total $10 $228

Feedstocks & Americas Styrenics Adjusted EBITDA ($MM) Adjusted EBITDA ($MM) $46 $42 $42 Q1'18 Q1'17 Q1'18 Q1'17 maintenance outage and higher 9 •Record Adjusted EBITDA in Q1 2018 •YoY increase due to prior year margins •Dividends: $30 million in Q1 2018 •Higher production volumes in current year due to prior year 6-week planned outage; offset by favorable prior year raw material timing $18 AMERICAS STYRENICS FEEDSTOCKS

$152 $137 $241 $294 $237 $322 $189 $206 $202 $231 $322 $262 $292 $256 $202 Apr-17 May-17 Jun-17 Jul-17 Aug-17 Sep-17 Oct-17 Nov-17 Dec-17 Jan-18 Feb-18 Mar-18 Apr-18 May-18 Jun-18 Styrene Margin - USD/MT Prices – USD/MT $482 $233 $319 $413 $428 $639 $476 $292 $306 $380 $612 $683 $555 $471 $426 Apr-17 May-17 Jun-17 Jul-17 Aug-17 Sep-17 Oct-17 Nov-17 Dec-17 Jan-18 Feb-18 Mar-18 Apr-18 May-18 Jun-18 Styrene Margin - USD/MT Prices – USD/MT Western Europe and Asia Styrene Margin Trends 10 Western Europe Margin (1) Asia Margin (2) Q1 to Q2 ~($75/MT) Trinseo’s Feedstocks reporting segment captures styrene monomer margin through both internally produced and cost-based purchases of styrene. In 2018, we estimate that we will produce approximately 700 kilotons of styrene in Western Europe and purchase approximately 185 kilotons of styrene in Asia with cost-based economics. With all other inputs remaining equal, a $50 per metric ton change in styrene margins would be expected to impact the Feedstocks reporting segment’s annual Adjusted EBITDA by approximately $35 million in Europe and approximately $9 million in Asia. Other factors that could impact the Feedstocks segment Adjusted EBITDA include, but are not limited to, utilities, freight, manufacturing costs, overhead costs, production outages, currency, discounts of styrene, benzene, and ethylene, as well as raw material timing. SOURCE: Western Europe Styrene, Benzene, Ethylene Prices: ICIS. Asia Styrene, Benzene, Ethylene prices: IHS. Styrene margin over raw materials: Trinseo. (1) Styrene: W. Europe Contract Monthly Market (Delivered W. Europe); Benzene: 50% W. Europe Spot Avg (CIF NW Europe / Basis ARA) and 50% W. Europe Contract – Market (FOB/CIF W. Europe); Ethylene: W. Europe Contract – Market Pipeline (Delivered W. Europe). (2) Styrene: NE Asia Avg Spot Posting (CFR China); Benzene: NE Asia Spot Avg (FOB S. Korea); Ethylene: NE Asia Spot Avg (CFR NE Asia). Styrene margin over raw materials: Styrene less (80% * Benzene) less (30% * Ethylene). Styrene Ethylene Benzene SM Margin over Raw Materials Styrene Ethylene Benzene SM Margin over Raw Materials Q1 to Q2 ~($25/MT)

Styrene Supply/Demand Outlook Projected Styrene Capacity Additions (kT) Global Styrene Supply / Demand Outlook 86% to 91% 85% to 89% +2,005 84% to 100% 89% Growth +668 +555 00 0% 2015 2016 2017 2018 2019 2020 2021 2022 2017 2018 2019 2020 2021 2022 Supply Op Rate - Base Demand Op Rate incl Closures/Delay (1) • • 2018 global supply of ~34,000 kilotons Supply outlook accounts for expected supply additions with no anticipated closures; demand outlook assumes 2.3% CAGR from 2017 to 2022 Increasing operating rates through 2019 2020 through 2022 operating rates consistent with levels of last several years • • (1) Assumes 500 kilotons of capacity closures in each of 2020, 2021, and 2022 as well as a 6-month delay in plants assumed to come onstream in 2020 through 2022 SOURCE: Trinseo 11 Supply / Demand (kT) Operating Rate Projected operating rates from 2019 to 2022 are expected to be in the mid to high 80s, similar to levels from 2015 to 2018 84%86%87%88%87% Demand +1,585 +6 +332

Q2 and Full Year 2018 Outlook Q2 Adj EBITDA* ($MM) FY Adj EBITDA* Assumptions ~$25 ~$105 YoY growth driven by SSBR capacity expansion and • $55 - $60 ~$255 draw) ~$45 ~$12 prices ~$25 ~$100 planned and unplanned outages $35 - $40 but still strong performance ~$145 ~($23) ~($95) Cash Paid for Interest of ~$50 million, Cash Paid for • Net Income Adjusted EBITDA* EPS Adj EPS* * See Appendix for reconciliation of non-GAAP measures $93 - $101 $160 - $170 $2.10 - $2.28 $2.10 - $2.28 $392 - $408 $665 - $685 $8.82 - $9.19 $8.87 - $9.24 12 • Effective tax rate of ~19% Income Taxes of ~$90 million, CapEx of ~$150 million Corporate • Lower Q2 margins as more styrene supply is available, • Includes known unplanned outage impacts Americas Styrenics • Q2 sequentially lower as styrene supply returns after • Includes known unplanned outage impacts Feedstocks • Stronger Q2 after Q1 destocking from higher styrene • Full year performance roughly flat YoY Polystyrene • Planned maintenance driving lower Q2 (inventory • Full year growth driven by ABS capacity, API Plastics Performance Plastics • Strong SSBR volume continues into Q2 new products Synthetic Rubber ~$30~$120• Continued steady performance Latex Binders

$100 Million Growth 2016 to 2018 Progress Aggregate Adjusted EBITDA1 ($MM) Target $52MM Growth +$32 ($9) 2016 SSPC Divestiture Latex Binders Synthetic Rubber Perf Plastics ex SSPC 2018 • $100 million growth target - growth across the Latex Binders, Synthetic Rubber, and Performance Plastics segments from 2016 to 2019 2016 to 2018 Aggregate Adjusted EBITDA increase of $52 million • • • Excludes impact from SSPC divestiture Includes $8 million of unfavorable net timing impacts • Includes significant improvement from our polycarbonate business (which is now reported in our Performance Plastics segment) Aggregate Adj EBITDA ($MM) 2016 94 111 232 2018 120 105 255 Latex Binders Adj EBITDA Synthetic Rubber Adj EBITDA Performance Plastics Adj EBITDA Aggregate Adj EBITDA 1) Aggregate Adjusted EBITDA is a non-GAAP financial performance measure, which we define as the sum of the segment Adjusted EBITDA for each of our Latex Binders, Synthetic Rubber, and Performance Plastics segments. We are providing management and investors with this performance measure as an indicator of the Company’s performance in reaching its growth target across these segments. For the reconciliation of this non-GAAP measure see the table on this slide 13. 437 480 13 +$26 $480 $437 ($6)

2018 Cash Generation $MM Net Income Guidance Midpoint 400 Adj EBITDA Guidance Midpoint Cash Paid for Income Taxes Cash Paid for Interest Business Services Transition Working Capital 675 (90) (50) (25) (30) • $30MM of structural working capital build from growth projects Assumes no other changes in working capital from raw material price changes, etc. • Cash from Operations CapEx 480 (150) Free Cash Flow 330 14

Appendix ™ Trademark of Trinseo S.A. or its affiliates

US GAAP to Non-GAAP Reconciliation 16 NOTE: For definitions of non-GAAP measures as well as descriptions of reconciling items from Net Income to Adjusted EBITDA and to Adjusted Net Income, refer to the accompanying Exhibit 99.1 – Press Release, May 2, 2018. Totals may not sum due to rounding. Profitability Outlook

US GAAP to Non-GAAP Reconciliation (in $millions, unless noted) Q1'15 Q2'15 Q3'15 Q4'15 Q1'16 Q2'16 Q3'16 Q4'16 Q1'17 Q2'17 Q3'17 Q4'17 Q1'18 2015 2016 2017 Net Income (Loss) Interest expense, net Provision for (benefit from) income taxes Depreciation and amortization EBITDA 37.7 28.9 17.9 22.5 0.8 25.6 7.5 21.7 52.1 19.5 21.2 23.0 43.1 19.3 23.6 29.5 76.7 18.9 21.9 23.2 95.8 18.8 28.6 24.9 67.3 18.8 16.0 23.8 78.5 18.4 20.5 24.7 117.3 18.2 29.3 24.7 60.2 18.7 18.8 26.3 33.2 18.4 8.3 29.2 117.7 14.8 26.4 30.3 120.3 14.9 24.9 31.9 133.6 93.2 70.2 96.8 318.3 75.0 87.0 96.4 328.3 70.1 82.8 110.6 107.0 55.6 115.8 115.5 140.7 168.1 125.9 142.1 189.5 124.0 89.1 189.2 192.0 393.8 576.7 591.8 Loss on extinguishment of long-term debt Other items Restructuring and other charges Net (gains) / losses on dispositions of businesses and assets Acquisition transaction and integration costs Asset impairment charges or write-offs Adjusted EBITDA - 1.3 0.5 - - - 95.2 0.6 (0.1) - - - - 0.3 0.1 - - - - - 0.2 - - - - 1.8 0.7 - - - - 0.3 1.1 12.9 - - - 0.3 16.8 0.3 - - - (6.8) 4.9 1.8 - - - - 2.1 (9.9) - - - - 1.1 - 1.1 - 65.3 1.6 1.5 0.2 3.8 4.3 - (21.6) 1.2 - (0.1) - - 2.7 0.5 (0.5) 0.3 - 95.2 2.2 0.8 - - - - (4.4) 23.5 15.1 - - 65.3 (19.9) 6.0 (9.7) 4.7 4.3 108.8 151.3 116.2 115.7 143.2 182.4 143.3 142.0 181.7 126.2 165.8 168.7 195.0 492.0 610.9 642.5 Adjusted EBITDA to Adjusted Net Income Adjusted EBITDA Interest expense, net Provision for (benefit from) income taxes - Adjusted Depreciation and amortization - Adjusted Adjusted Net Income Wtd Avg Shares - Diluted (000) Adjusted EPS - Diluted ($) 108.8 28.9 18.3 22.3 151.3 25.6 25.5 21.6 116.2 19.5 22.3 22.1 115.7 19.3 18.7 23.4 143.2 18.9 22.4 22.6 182.4 18.8 28.8 24.9 143.3 18.8 21.4 23.3 142.0 18.4 22.0 24.7 181.7 18.2 29.5 24.2 126.2 18.7 19.2 25.8 165.8 18.4 21.0 28.6 168.7 14.8 28.4 30.0 195.0 14.9 26.0 31.7 492.0 93.2 84.9 89.3 610.9 75.0 94.6 95.4 642.5 70.1 98.2 108.6 39.3 48,851 0.80 78.6 48,907 1.61 52.3 48,989 1.07 54.3 49,067 1.11 79.3 49,086 1.62 109.9 47,857 2.30 79.8 46,961 1.70 76.9 45,754 1.68 109.8 45,313 2.42 62.5 44,995 1.39 97.8 44,782 2.18 95.5 44,734 2.14 122.4 44,430 2.76 224.6 48,970 4.59 345.9 47,478 7.28 365.6 44,973 8.13 Adjustments b y Statement of Operations Caption Loss on extinguishment of long-term debt Cost of sales Selling, general and administrative expenses Other expense (income), net Total EBITDA Adjustments - - 1.8 - 95.2 - 0.5 - - - 0.4 - - - 0.2 - - - 2.5 - - - 1.4 12.9 - - 17.1 0.3 - - 4.9 (5.0) - - 2.1 (9.9) - - 2.2 - 65.3 2.4 7.6 1.4 - (18.4) (2.1) - - - 3.5 (0.5) 95.2 - 3.0 - - - 25.9 8.3 65.3 (16.0) 9.9 (8.5) 1.8 95.7 0.4 0.2 2.5 14.3 17.4 (0.1) (7.8) 2.2 76.7 (20.5) 3.0 98.2 34.2 50.7 Free Cash Flow Reconciliation Cash provided by operating activities Capital expenditures Free Cash Flow 84.9 (26.4) 94.8 (26.7) 145.0 (29.5) 79.0 (41.2) (25.7) (36.0) 62.3 (38.2) 158.3 (34.6) 196.5 (38.5) 40.8 (30.6) 421.9 (109.3) 403.7 (123.9) 391.3 (147.4) 58.4 68.1 115.5 37.8 (61.7) 24.1 123.7 158.0 10.2 312.6 279.8 243.9 NOTE: Totals may not sum due to rounding. 17

Selected Segment Information (in $millions, unless noted) Q1'15 Q2'15 Q3'15 Q4'15 Q1'16 Q2'16 Q3'16 Q4'16 Q1'17 Q2'17 Q3'17 Q4'17 Q1'18 2015 2016 2017 Latex Binders Synthetic Rubber Performance Plastics Polystyrene Feedstocks Trade Volume (MMLbs) 305 162 338 397 209 312 153 335 373 151 307 152 314 324 231 308 134 297 374 165 299 146 335 377 194 310 148 342 352 195 318 150 314 335 207 309 159 302 341 163 301 179 344 311 168 287 158 325 345 238 298 137 337 351 206 276 144 339 342 224 274 164 351 308 143 1,233 601 1,283 1,467 755 1,236 604 1,293 1,404 759 1,161 617 1,345 1,349 836 1,411 1,323 1,327 1,277 1,352 1,347 1,324 1,273 1,302 1,352 1,329 1,325 1,241 5,339 5,296 5,308 Latex Binders Synthetic Rubber Performance Plastics Polystyrene Feedstocks Net Sales 238 129 339 233 78 248 115 334 262 69 255 126 322 223 103 226 104 297 211 60 209 102 304 208 71 232 111 326 221 79 243 113 301 198 81 241 124 287 201 64 289 163 337 228 87 292 174 339 233 107 266 119 362 238 111 250 127 381 241 103 255 149 403 240 75 966 475 1,292 929 310 925 451 1,218 828 294 1,097 583 1,419 941 408 1,018 1,029 1,028 897 894 970 935 917 1,104 1,145 1,097 1,102 1,122 3,972 3,717 4,448 Latex Binders Synthetic Rubber Performance Plastics Polystyrene Feedstocks Americas Styrenics Corporate Adjusted EBITDA 21 26 34 11 5 35 (23) 15 18 44 24 35 41 (25) 24 27 42 3 7 32 (21) 18 21 50 17 3 27 (20) 19 23 59 14 21 33 (25) 21 30 66 15 33 38 (21) 30 28 53 11 13 34 (26) 24 29 53 12 14 31 (22) 37 46 52 14 42 18 (27) 36 28 48 7 (1) 30 (22) 32 (6) 62 9 46 44 (22) 33 15 68 19 24 31 (21) 27 26 66 10 42 46 (20) 79 93 169 54 51 135 (90) 94 111 232 52 80 136 (95) 139 83 231 48 111 123 (92) 109 151 116 116 143 182 143 142 182 126 166 169 195 492 611 642 Adj EBITDA Variance Analysis Net Timing* Impacts - Fav/(Unfav) Latex Binders Synthetic Rubber Performance Plastics Polystyrene Feedstocks Net Timing* Impacts - Fav/(Unfav) 6 (6) 6 (7) (8) (5) 1 2 9 12 0 1 (4) (7) (13) 2 (1) 1 1 (3) (0) (4) 3 (1) (2) (4) 3 (3) 1 4 2 1 (1) 1 1 2 6 1 1 4 (8) 16 (2) 4 11 1 (4) (3) (5) (11) (5) (25) 1 1 4 4 0 2 3 7 (4) 2 (0) (2) (3) 4 (5) 5 (5) (13) (0) 6 0 2 7 (8) (13) (2) 3 11 (9) 19 (24) (0) (4) 0 5 14 22 (23) (24) 15 (7) (14) 15 (9) *Net Timing is the difference between Raw Material Timing and Price Lag. Raw Material Timing represents the timing of raw material cost changes flowing through cost of goods sold versus current pricing. Price Lag represents the difference in revenue between the current contractual price and the current period price. NOTE: Totals may not sum due to rounding. 18