X0306 4 2018-05-02 0001049502 MKS INSTRUMENTS INC MKSI 0001106180 BERTUCCI JOHN R 2 TECH DRIVE ANDOVER MA 01810 1 Common Stock 2018-05-02 5 G 0 E 60996 0 D 0 I By John R. Bertucci 2016 Qualified Annuity Trust Common Stock 2018-05-02 5 G 0 E 68336 0 D 0 I By Claire R. Bertucci 2016 Qualified Annuity Trust Common Stock 197248.102 D Common Stock 51000 I By Claire R. Bertucci 2016 Second Qualified Annuity Trust Common Stock 27782 I By John R. Bertucci 2016 Second Qualified Annuity Trust Common Stock 186505 I By Spouse The reporting person's 2016 Grantor Retained Annuity Trust terminated. On May 2, 2018, 60,996 shares in this trust were transferred to the reporting person's beneficiaries and the remaining 25,976 shares were distributed to the reporting person and are reported in this Form 4 as directly owned by the reporting person. The reporting person's spouse's 2016 Grantor Retained Annuity Trust terminated. On May 2, 2018, 68,336 shares in this trust were transferred to the reporting person's spouse's beneficiaries and the remaining 19,355 shares were distributed to the reporting person's spouse and continue to be reported in this Form 4 as indirectly owned by the reporting person's spouse. /s/ M. Kathryn Rickards, attorney-in-fact 2018-05-04