[Form 4] MKS INC Insider Trading Activity

Rhea-AI Filing Summary

Henry David Philip, Executive VP & GM at MKS Inc., reported a sale of 5,000 shares of MKS Inc. common stock on 09/18/2025 at a price of $130 per share, leaving beneficial ownership of 15,571.18 shares. The filing states the sale was made under a Rule 10b5-1 trading plan adopted March 12, 2025. The Form 4 was signed by an attorney-in-fact on 09/19/2025. No derivative transactions or other securities classes are reported in this filing.

Positive

• Sale executed under a Rule 10b5-1 trading plan, indicating a pre-established, compliance-oriented disposition
• Timely disclosure with the Form 4 signed on 09/19/2025 following the 09/18/2025 transaction

Negative

• Insider reduced holdings: 5,000 shares were sold, decreasing beneficial ownership to 15,571.18 shares

Insights

Financial Analyst

TL;DR: A routine insider sale of 5,000 MKSI shares under a pre-established 10b5-1 plan; appears non-eventful for fundamentals.

The sale on 09/18/2025 of 5,000 shares at $130 was executed under a Rule 10b5-1 plan adopted 03/12/2025, which typically signals pre-arranged disposition rather than an unscheduled reaction to material company developments. Reported post-transaction beneficial ownership is 15,571.18 shares. No derivatives or other transactions are disclosed. From a financial-materiality standpoint, the filing documents an insider liquidity event but contains no new operational or financial metrics.

Corporate Governance Expert

TL;DR: Disclosure follows standard Section 16 reporting practices; use of a 10b5-1 plan supports procedural compliance.

The Form 4 shows appropriate disclosure of an officer-level sale and cites a 10b5-1 plan adoption date, which helps establish compliance with insider trading rules. The form is signed via attorney-in-fact and lists direct ownership impact. There are no indications of late reporting or undisclosed related-party transactions in the document provided.

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
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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).

1. Name and Address of Reporting Person^*

Henry David Philip

(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, Global Str Mktg & GM, MSD

3. Date of Earliest Transaction (Month/Day/Year)
09/18/2025

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	09/18/2025		S(1)		5,000	D	$130	15,571.18	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

Explanation of Responses:

1. This transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 12, 2025.

	/s/ M. Kathryn Rickards, attorney-in-fact	09/19/2025
	** 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).
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 MKSI report on 09/18/2025?

The filing reports that Henry David Philip sold 5,000 shares of MKSI common stock on 09/18/2025 at $130 per share.

Was the MKSI insider sale executed under a 10b5-1 plan?

Yes. The Form 4 states the transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 12, 2025.

How many MKSI shares does the reporting person own after the transaction?

The Form 4 shows beneficial ownership of 15,571.18 shares following the reported sale.

Who signed the Form 4 for the MKSI filing?

The Form 4 was signed by M. Kathryn Rickards, attorney-in-fact, on 09/19/2025.

Did the Form 4 disclose any derivative transactions for MKSI?

No. The filing contains no entries in Table II and discloses only the non-derivative sale of common stock.