Avantor, Inc.

Securities Trading Plans of Directors and Officers

Our directors and officers (as defined in Exchange Act Rule 16a-1(f)) may from time to time enter into plans or other arrangements for the purchase or sale of our shares that are intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) of the Securities Exchange Act of 1934. During the quarter ended June 30, 2025, the following plans or arrangements were adopted:

On May 6, 2025, Michael Stubblefield, Director, President and Chief Executive Officer, adopted a Rule 10b5-1 trading plan (the “Plan”) intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) of the Securities Exchange Act of 1934, pursuant to which he may sell up to 906,204 shares of the Company’s common stock through the exercise of stock options in amounts and at prices as determined in accordance with the Plan terms. The Plan will terminate on the earlier of October 31, 2025, or the execution of all trades contemplated by the Plan.

No other directors or officers, as defined in Rule 16a-1(f) of the Securities Exchange Act of 1934, of the Company adopted orterminated (i) a Rule 10b5-1 trading arrangement, as defined in Item 408(a) under Regulation S-K, or (ii) a non-Rule 10b5-1 trading arrangement, as defined in Item 408(c) under Regulation S-K, during the three months ended June 30, 2025.