X0306 4 2016-09-23 0 0001519061 Trinseo S.A. TSE 0001683853 Springham Ruth C/O BAIN CAPITAL LUXEMBOURG S.A R.L. 4 RUE LOU HEMMER LUXEMBOURG N4 LUXEMBOURG 1 0 1 0 ORDINARY SHARES 2016-09-23 4 S 0 10669567 54.05 D 0 I See Footnotes Represents 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"). Ms. Springham is a manager of BCEM. By virtue of the relationships described in these footnotes, Ms. Springham may be deemed to share voting and dispositive power with respect to the shares of Trinseo S.A. held by BCEM Holding. Ms. Springham disclaims beneficial ownership of such securities except to the extent of her pecuniary interest therein. RUTH SPRINGHAM 2016-09-27