X0306 4 2019-05-21 0 0001722482 Avantor, Inc. AVTR 0001068731 GUPTA RAJIV C/O NEW MOUNTAIN CAPITAL, 787 7TH AVENUE, 49TH FLOOR NEW YORK NY 10019 1 0 0 0 Common Stock 2019-05-21 4 A 0 14286 0.00 A 554427 D Common Stock 2019-05-21 4 M 0 523286 A 843791 I See footnote Existing Junior Convertible Preferred 2019-05-21 4 M 0 4440 0.00 D Common Stock 523286 0 I See footnote Reflects a grant of restricted stock units that vests on May 21, 2020. Existing Junior Convertible Preferred Stock automatically converted into common stock of the Issuer upon consummation of the Issuer's initial public offering. The number of shares of common stock received upon conversion of the Existing Junior Convertible Preferred Stock was based on the aggregate liquidation preference of such stock divided by the initial public offering price of $14.00 per share. Reflects securities held by a trust for the benefit of the Reporting Person's family, of which the spouse of the Reporting Person is trustee. Reporting Person disclaims beneficial ownership of the securities held by the trust, except to the extent of his pecuniary interest therein. The Existing Junior Convertible Preferred were inadvertently reported as directly held by the Reporting Person on the Form 3 filed by him on May 16, 2019. /s/ Scott Baker, as Attorney-in-Fact 2019-05-23