NOTE 15SEGMENTS Through December 31, 2017, the Company operated under two divisions: Performance Materials and Basic Plastics &amp; Feedstocks. The Performance Materials division included the following reporting segments: Latex Binders, Synthetic Rubber, and Performance Plastics. The Basic Plastics &amp; Feedstocks division included the following reporting segments: Basic Plastics, Feedstocks, and Americas Styrenics. Effective January 1, 2018, the Company realigned its reporting segments to reflect the new model under which the business will be managed and results will be reviewed by the chief executive officer, who is the Companys chief operating decision maker. Under this new segmentation, the Company will no longer have divisions, but will continue to report operating results for six segments, four of which remain unchanged from the Companys prior segmentation: Latex Binders, Synthetic Rubber, Feedstocks, and Americas Styrenics. The results of the Companys Polystyrene business, which were previously included within the results of the Basic Plastics segment, are now reported as a stand-alone segment. Performance Plastics, which previously consisted of compounds, blends, and ABS products sold to the automotive market, now includes the remaining portion of the Companys ABS business, as well as the results of the Companys SAN and PC businesses. This segmentation change will provide enhanced clarity to investors by concentrating the Companys more specialized plastics into a single reporting segment, while also reducing complexity as PC and ABS are the primary inputs into the downstream production of the Companys compounds and blends. The information in the tables below has been retroactively adjusted to reflect the changes in reporting segments. The 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 number of performance latex binders applications, such as adhesive, building and construction and the technical textile paper market. The Synthetic Rubber segment produces synthetic rubber products used predominantly in high-performance tires, impact modifiers and technical rubber products, such as conveyer belts, hoses, seals and gaskets. The Performance Plastics segment produces highly engineered compounds and blends, and also includes the Companys ABS, SAN, and PC businesses. The Performance Plastics segment, as recast, also included the results of the Companys previously 50%-owned joint venture, Sumika Styron Polycarbonate, until the Company sold its share in the entity in January 2017 (refer to Note 4 for further information). Polystyrene is a stand-alone reporting segment, and includes a variety of general purpose polystyrenes (GPPS) and polystyrene that has been modified with polybutadiene rubber to increase its impact resistant properties (HIPS). The Feedstocks segment includes the Companys production and procurement of styrene monomer outside of North America, which is used as a key raw material in many of the Companys products, including polystyrene, SB latex, ABS resins, solution styrene-butadiene rubber (SSBR), etc. Lastly, the Americas Styrenics segment consists solely of the operations of the Companys 50%-owned joint venture, Americas Styrenics, a producer of both styrene monomer and polystyrene in North America. Asset and intersegment sales information by reporting segment is not regularly reviewed or included with the Companys reporting to the chief operating decision maker. Therefore, this information has not been disclosed below. Latex Synthetic Performance Americas Corporate Three Months Ended Binders Rubber Plastics Polystyrene Feedstocks Styrenics Unallocated Total September 30, 2018 Sales to external customers $ 278.0 $ 137.7 $ 400.7 $ 252.3 $ 131.0 $  $  $ 1,199.7 Equity in earnings of unconsolidated affiliates      34.5  34.5 Adjusted EBITDA (1) 24.7 15.5 43.8 5.0 40.3 34.5 Investment in unconsolidated affiliates      180.8  180.8 Depreciation and amortization 6.2 10.6 6.9 2.9 2.9  2.3 31.8 September 30, 2017 Sales to external customers $ 266.3 $ 118.7 $ 362.2 $ 238.4 $ 111.0 $  $  $ 1,096.6 Equity in earnings of unconsolidated affiliates      43.8  43.8 Adjusted EBITDA (1) 32.3 (5.6) 62.4 9.1 45.6 43.8 Investment in unconsolidated affiliates      161.9  161.9 Depreciation and amortization 6.0 9.0 5.3 3.1 3.6  2.2 29.2 Latex Synthetic Performance Americas Corporate Nine Months Ended Binders Rubber Plastics Polystyrene Feedstocks Styrenics Unallocated Total September 30, 2018 Sales to external customers $ 814.2 $ 442.2 $ 1,216.2 $ 777.5 $ 307.7 $  $  $ 3,557.8 Equity in earnings of unconsolidated affiliates      113.3  113.3 Adjusted EBITDA (1) 88.2 71.6 158.2 28.0 114.3 113.3 Investment in unconsolidated affiliates      180.8  180.8 Depreciation and amortization 18.6 33.1 20.0 8.6 8.9  6.8 96.0 September 30, 2017 Sales to external customers $ 846.7 $ 456.1 $ 1,038.4 $ 700.2 $ 304.9 $  $  $ 3,346.3 Equity in earnings of unconsolidated affiliates   0.8   92.2  93.0 Adjusted EBITDA (1) 105.2 68.4 162.9 29.6 86.3 92.2 Investment in unconsolidated affiliates      161.9  161.9 Depreciation and amortization 17.5 26.0 13.7 7.3 9.2  6.4 80.1 (1) The Companys 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 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 Companys segment performance. The reconciliation of income before income taxes to Segment Adjusted EBITDA is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Income before income taxes $ 93.9 $ 41.5 $ 357.8 $ 267.1 Interest expense, net 10.1 18.4 35.8 55.4 Depreciation and amortization 31.8 29.2 96.0 80.1 Corporate Unallocated (2) 20.9 21.8 65.6 70.8 Adjusted EBITDA Addbacks (3) 7.1 76.7 18.4 71.2 Segment Adjusted EBITDA $ 163.8 $ 187.6 $ 573.6 $ 544.6 (2) Corporate unallocated includes corporate overhead costs and certain other income and expenses. (3) Adjusted EBITDA addbacks for the three and nine months ended September 30, 2018 and 2017 are as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Loss on extinguishment of long-term debt (Note 6) $  $ 65.3 $ 0.2 $ 65.3 Net loss (gain) on disposition of businesses and assets (Note 4)  0.2 (0.5) (9.7) Restructuring and other charges (Note 16) 0.9 1.5 2.6 4.8 Acquisition transaction and integration costs (Note 14) 0.1 3.8 0.6 4.9 Asset impairment charges or write-offs (a)  4.3  4.3 Other items (b) 6.1 1.6 15.5 1.6 Total Adjusted EBITDA Addbacks $ 7.1 $ 76.7 $ 18.4 $ 71.2 (a) Asset impairment charges for the three and nine months ended September 30, 2017 primarily relate to the impairment of certain long-lived assets in the Companys Performance Plastics segment. (b) Other items for the three and nine months ended September 30, 2018 primarily relate to advisory and professional fees incurred in conjunction with the Companys initiative to transition business services from Dow, including certain administrative services such as accounts payable, logistics, and IT services. Also included within other items for the nine months ended September 30, 2018 are fees incurred in conjunction with the Companys 2024 Term Loan B repricing which was completed during the second quarter of 2018. Other items for the three and nine months ended September 30, 2017 primarily relate to fees incurred in conjunction with the Companys debt refinancing which was completed during the third quarter of 2017.