F1Represents ordinary shares of Trinseo S.A. held by Bain Capital Everest Manager Holding SCA ("BCEM Holding"), whose general partner is Bain Capital Everest Manager S.a r.l. ("BCEM"). On August 12, 2016, BCEM Holding sold 8,000,000 Ordinary Shares. Following such sale, BCEM Holding held 10,669,567 Ordinary Shares.
F2All of the outstanding share capital of BCEM is held by Bain Capital Europe Fund III, L.P. ("Europe Fund III") and, in that capacity, Europe Fund III has the power to appoint the managers of BCEM. Bain Capital Investors, LLC ("BCI") is the general partner of Bain Capital Partners Europe III, L.P. ("Partners Europe III"), which is the general partner of Europe Fund III. BCI is also the general partner of Bain Capital Partners X, L.P. ("Partners X"), which is the general partner of Bain Capital Fund X, L.P. ("Fund X"). Boylston Coinvestors, LLC is the general partner of BCIP Associates IV, L.P. ("BCIP IV"), BCIP Associates IV-B, L.P. ("BCIP IV-B"), BCIP Trust Associates IV, L.P. ("BCIP Trust IV") and BCIP Trust Associates IV-B, L.P. ("BCIP Trust IV-B," and, together with BCEM Holdings, BCEM, Europe Fund III, Partners Europe III, Fund X, Partners X, BCIP IV, BCIP IV-B and BCIP Trust IV, the "Bain Capital Entities").
F3The governance, investment strategy and decision-making process with respect to the investments held by all of the Bain Capital Entities is directed by BCI's Global Private Equity Board. As a result, BCI may be deemed to share voting and dispositive power with respect to the shares of Trinseo S.A. held by BCEM Holding. BCI disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein.

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