John Tseng-Chung Lee - 30 Oct 2026 Form 4 Insider Report for MKS INC (MKSI)

Reporting relationship: President & CEO, Director
Issuer ticker: MKSI
Reported as of: 30 Oct 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 03 Nov 2026, 16:41:42 UTC
Prior SEC filing: 17 Aug 2026
Source filing: View source filing
Reporting owner signature: /s/ M. Kathryn Rickards, attorney-in-fact

Filing notes and source

Key filing fact

John Tseng-Chung Lee filed Form 4 for MKS INC (MKSI) on 03 Nov 2026.

Key facts

This page summarizes John Tseng-Chung Lee's Form 4 filing for MKS INC (MKSI).
5 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 03 Nov 2026, 16:41.

Change

Previous filing in this sequence was filed on 17 Aug 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001414656 Primary reporting owner

Lee John Tseng-Chung

Relationship: President & CEO, Director
Address: C/O MKS INC., 2 TECH DRIVE, ANDOVER
Signature: /s/ M. Kathryn Rickards, attorney-in-fact
Signature date: 03 Nov 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

MKSI transaction

Common Stock

Options Exercise

Transaction value
Shares: +1,479
Change %: +1.1%
Price
Shares after: 136,255
Date: 30 Oct 2026
Ownership: Direct
Footnotes: F1

MKSI transaction

Common Stock

Options Exercise

Transaction value
Shares: +679
Change %: +0.5%
Price
Shares after: 136,934
Date: 30 Oct 2026
Ownership: Direct
Footnotes: F1

MKSI transaction

Common Stock

Tax liability

Transaction value
Shares: -2,157
Change %: -1.6%
Price: $202.04^*
Shares after: 134,776
Date: 30 Oct 2026
Ownership: Direct
Footnotes: F2

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

MKSI transaction Derivative

Restricted Stock Unit

Options Exercise

Transaction value
Shares: -1,479
Change %: -1.7%
Price
Shares after: 83,349
Date: 30 Oct 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 1,479
Exercise price
Footnotes: F1, F3

MKSI transaction Derivative

Restricted Stock Unit

Options Exercise

Transaction value
Shares: -679
Change %: -0.81%
Price
Shares after: 82,671
Date: 30 Oct 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 679
Exercise price
Footnotes: F1, F4

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 4 footnotes

Footnote F1

Each restricted stock unit (RSU) represents the contingent right to receive one share of common stock of MKS Inc.

Footnote F2

Shares used to satisfy FICA taxes.

Footnote F3

Portion of 2025 RSU Award accelerated to satisfy FICA taxes.

Footnote F4

Portion of 2026 RSU Award accelerated to satisfy FICA taxes.