[Form 4] MKS INC Insider Trading Activity

Rhea-AI Filing Summary

MKS Inc. executive reports RSU vesting and related share withholding. The company’s EVP & CFO reported the vesting of 8,295 restricted stock units on common stock of MKS Inc. on 11/17/2025, each RSU representing the right to receive one share of common stock.

Of these shares, 2,628 were withheld by MKS Inc. at a price of $142.74 per share to cover tax withholding obligations, leaving 5,667 shares of common stock beneficially owned directly after the transaction. Following this activity, the executive also reports 16,402.394 restricted stock units beneficially owned, which continue to represent future rights to receive common shares as they vest in scheduled installments.

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

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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^*

Mayampurath Ramakumar

(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 & CFO

3. Date of Earliest Transaction (Month/Day/Year)
11/17/2025

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	11/17/2025		M		8,295	A	(1)	8,295	D
Common Stock	11/17/2025		F(2)		2,628	D	$142.74	5,667	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)	11/17/2025		M			8,295	(3)	(3)	Common Stock	8,295	(1)	16,402.394	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 equal annual installments commencing on November 15, 2025, provided that if, in any vesting year, November 15th is not a business day, such vesting shall occur on the next business day.

	/s/ James Kruger, attorney-in-fact	11/18/2025
	** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did MKS Inc. (MKSI) report in this Form 4?

The EVP & CFO of MKS Inc. reported the vesting of 8,295 restricted stock units (RSUs) into common stock on 11/17/2025, along with related tax share withholding.

How many MKS Inc. (MKSI) shares were withheld for taxes in this filing?

MKS Inc. withheld 2,628 shares of common stock at a price of $142.74 per share to satisfy tax withholding obligations arising from the RSU vesting.

How many MKS Inc. (MKSI) shares does the executive own after this transaction?

After the reported transactions, the EVP & CFO directly beneficially owns 5,667 shares of MKS Inc. common stock.

What are the terms of the MKS Inc. RSUs mentioned in the Form 4?

Each restricted stock unit represents the contingent right to receive one share of MKS Inc. common stock, subject to vesting conditions described in the filing.

How many MKS Inc. (MKSI) RSUs does the executive still hold after this Form 4?

Following the transactions, the executive reports beneficial ownership of 16,402.394 restricted stock units, which entitle him to receive common shares as they vest.

Are the share withholdings in this MKS Inc. Form 4 discretionary trades?

No. The filing states that the 2,628 shares were withheld by MKS Inc. to satisfy tax withholding obligations and do not represent a discretionary trade by the reporting person.

When do the reported MKS Inc. RSUs vest?

The filing explains that the RSUs vest in two equal annual installments commencing on November 15, 2025, or the next business day if November 15 is not a business day.