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 OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	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 INSTRUMENTS, INC. 2 TECH DRIVE, SUITE 201 (Street) ANDOVER MA 01810 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol MKS INSTRUMENTS 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, MSD
	3. Date of Earliest Transaction (Month/Day/Year) 02/15/2024
	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	02/15/2024		M		1,306.861	A	(1)	12,874.299	D
Common Stock	02/15/2024		M		653.93	A	(1)	13,528.229	D
Common Stock	02/15/2024		M		1,629	A	(1)	15,157.229	D
Common Stock	02/15/2024		M		1,173	A	(1)	16,330.229	D
Common Stock	02/15/2024		M		2,565	A	(1)	18,895.229	D
Common Stock	02/15/2024		M		1,329	A	(1)	20,224.229	D
Common Stock	02/15/2024		F(2)		3,756	D	$122.15	16,468.229	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)	02/15/2024		A		3,633.428		(3)	(3)	Common Stock	3,633.428	(1)	22,885.258	D
Restricted Stock Unit	(1)	02/15/2024		M			1,306.861	(4)	(4)	Common Stock	1,306.861	(1)	21,578.397	D
Restricted Stock Unit	(1)	02/15/2024		M			653.93	(5)	(5)	Common Stock	653.93	(1)	20,924.467	D
Restricted Stock Unit	(1)	02/15/2024		M			1,629	(6)	(6)	Common Stock	1,629	(1)	19,295.467	D
Restricted Stock Unit	(1)	02/15/2024		M			1,173	(7)	(7)	Common Stock	1,173	(1)	18,122.467	D
Restricted Stock Unit	(1)	02/15/2024		M			2,565	(8)	(8)	Common Stock	2,565	(1)	15,557.467	D
Restricted Stock Unit	(1)	02/15/2024		M			1,329	(9)	(9)	Common Stock	1,329	(1)	14,228.467	D

Explanation of Responses:

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

2. These shares were withheld by MKS Instruments, 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 three equal annual installments commencing on February 15, 2025, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.

4. These RSUs were subject to performance criteria, the achievement of which was determined on January 21, 2022, and thereafter vest in three equal annual installments beginning on February 15, 2022, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.

5. These RSUs vest in three equal annual installments commencing on February 15, 2022, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.

6. These RSUs were subject to performance criteria, the achievement of which was determined on February 8, 2023, and thereafter vest in three equal annual installments beginning on February 15, 2023, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.

7. These RSUs vest in three equal annual installments commencing on February 15, 2023, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.

8. These RSUs were subject to performance criteria, the achievement of which was determined on February 5, 2024, and thereafter vest in three equal annual installments beginning on February 15, 2024, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.

9. These RSUs vest in three equal annual installments commencing on February 15, 2024, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day.

	/s/ M. Kathryn Rickards, attorney-in-fact	02/16/2024
	** Signature of Reporting Person	Date
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