X0206 3 2019-05-16 0 0001722482 Avantor, Inc. AVTR 0001515175 New Mountain Investments III, LLC C/O NEW MOUNTAIN CAPITAL 787 7TH AVENUE, 49TH FLOOR NEW YORK NY 10019 0 0 1 0 0001403510 New Mountain Partners III LP C/O NEW MOUNTAIN CAPITAL 787 7TH AVENUE, 49TH FLOOR NEW YORK NY 10019 0 0 1 0 0001407718 New Mountain Capital, L.L.C. C/O NEW MOUNTAIN CAPITAL 787 7TH AVENUE, 49TH FLOOR NEW YORK NY 10019 0 0 1 0 0001777024 New Mountain Capital Group, L.P. C/O NEW MOUNTAIN CAPITAL 787 7TH AVENUE, 49TH FLOOR NEW YORK NY 10019 0 0 1 0 0001776766 NM Holdings GP, L.L.C. C/O NEW MOUNTAIN CAPITAL 787 7TH AVENUE, 49TH FLOOR NEW YORK NY 10019 0 0 1 0 0001018327 KLINSKY STEVEN B C/O NEW MOUNTAIN CAPITAL 787 7TH AVENUE, 49TH FLOOR NEW YORK NY 10019 0 0 1 0 Common Stock 110478090 I See Footnote These securities are directly held by New Mountain Partners III, L.P. The general partner of New Mountain Partners III, L.P. is New Mountain Investments III, L.L.C. and the manager of New Mountain Partners III, L.P. is New Mountain Capital, L.L.C. Steven B. Klinsky is the managing member of New Mountain Investments III, L.L.C. The managing member of New Mountain Capital, L.L.C. is New Mountain Capital Group, L.P. The general partner of New Mountain Capital Group, L.P. is NM Holdings GP, L.L.C. Steven B. Klinsky is the managing member of NM Holdings GP, L.L.C. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein, except to the extent of such Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed to be an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the Reporting Persons are the beneficial owners of any securities reported herein. NEW MOUNTAIN PARTNERS III, L.P., By: New Mountain Investments III, L.L.C., its general partner, By: /s/ Steven B. Klinsky, Name: Steven B. Klinsky, Title: Managing Member 2019-05-16 NEW MOUNTAIN INVESTMENTS III, L.L.C., By: /s/ Steven B. Klinsky, Name: Steven B. Klinsky, Title: Managing Member 2019-05-16 NEW MOUNTAIN CAPITAL, L.L.C., By: New Mountain Capital Group, L.P., its managing member, By: NM Holdings GP, L.L.C., its general partner, By: /s/ Steven B. Klinsky, Name: Steven B. Klinsky, Title: Managing Member 2019-05-16 NEW MOUNTAIN CAPITAL GROUP, L.P., By: NM Holdings GP, L.L.C., its general partner, By: /s/ Steven B. Klinsky, Name: Steven B. Klinsky, Title: Managing Member 2019-05-16 NM HOLDINGS GP, L.L.C., By: /s/ Steven B. Klinsky, Name: Steven B. Klinsky, Title: Managing Member 2019-05-16 /s/ Steven B. Klinsky 2019-05-16