[Form 4] MKS Inc. Insider Trading Activity

Rhea-AI Filing Summary

James Alan Schreiner, EVP & COO of MKS Inc. (MKSI), reported transactions dated 08/18/2025 related to vested restricted stock units (RSUs) and a related share withholding sale to cover taxes. The filing shows 2,640.942 RSUs treated as acquired (vesting) and 1,249 shares disposed of in a withholding sale at $100.22 per share to satisfy tax obligations. The filing states each RSU converts to one common share. The reporting person’s post-transaction beneficial ownership is reported as 24,083.694 shares for non-derivative common stock and 13,018.14 derivative securities beneficially owned following the transactions. The report was signed by an attorney-in-fact on behalf of the reporting person.

Positive

• Clear disclosure of RSU vesting and related tax withholding
• Post-transaction beneficial ownership figures are provided, enhancing transparency

Negative

• 1,249 shares were disposed of via withholding (tax settlement), reducing outstanding personal shares

Insights

Corporate Governance Expert

TL;DR: Routine executive compensation vesting with tax withholding; standard disclosure for insider ownership changes.

The Form 4 documents customary RSU vesting and a contemporaneous share withholding to satisfy tax obligations rather than an open-market sale. This is a common practice that preserves executive shareholdings while meeting tax liabilities. The filing clearly identifies the reporting person as EVP & COO and provides explicit post-transaction ownership figures, supporting transparency in insider holdings. There are no indications of opportunistic trading or unusual timing within the filing text.

Compensation Analyst

TL;DR: Compensation mechanics visible: 2,640.942 RSUs vested and 1,249 shares withheld at $100.22 for taxes.

The statements show a tranche of RSUs converted into shares and a portion withheld to satisfy tax withholding obligations. The RSU vesting schedule referenced (60%/40% on specified August dates) explains the timing and quantity. The disclosed withholding of 1,249 shares at $100.22 reflects cost-recovery for payroll tax and is reported as a disposal without suggesting discretionary sale behavior.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Schreiner James Alan

(Last) (First) (Middle)

C/O MKS INC.

2 TECH DRIVE

(Street)

ANDOVER MA 01810

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
MKS INC [ MKSI ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP & COO

3. Date of Earliest Transaction (Month/Day/Year)
08/18/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/18/2025		M		2,640.942	A	(1)	25,332.694	D
Common Stock	08/18/2025		F(2)		1,249	D	$100.22	24,083.694	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Unit	(1)	08/18/2025		M			2,640.942	(3)	(3)	Common Stock	2,640.942	(1)	13,018.14	D

Explanation of Responses:

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

2. These shares were withheld by MKS Inc. to satisfy the tax withholding obligations triggered by the vesting of RSUs and do not represent a discretionary trade by the reporting person.

3. These RSUs vest in two installments, 60% of which shall vest on August 17, 2024 and 40% of which shall vest on August 17, 2025; provided that if, in any vesting year, August 17th is not a business day, such vesting shall occur on the next business day.

	/s/ M. Kathryn Rickards, attorney-in-fact	08/19/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

What transactions did MKSI insider James Alan Schreiner report on 08/18/2025?

The filing reports 2,640.942 RSUs vesting and a withholding disposal of 1,249 shares at $100.22 per share to satisfy tax obligations.

How many shares does the reporting person own after the reported MKSI transactions?

The report lists 24,083.694 shares of non-derivative common stock and 13,018.14 derivative securities beneficially owned following the transactions.

Why were 1,249 MKSI shares disposed of according to the Form 4?

The filing states those shares were withheld by MKS Inc. to satisfy tax withholding obligations triggered by RSU vesting.

What is the vesting schedule disclosed for the RSUs in the MKSI Form 4?

The RSUs vest in two installments: 60% on August 17, 2024 and 40% on August 17, 2025, with business-day adjustment.

Who signed the MKSI Form 4 filing for the reporting person?

The form was signed by M. Kathryn Rickards as attorney-in-fact on 08/19/2025.