Schedule 13G/A: T. Rowe Price Reports 4,129,128 MKSI Shares

Rhea-AI Filing Summary

T. Rowe Price Associates, Inc. filed Amendment No. 4 to a Schedule 13G reporting ownership of 4,129,128 shares of MKS Inc. common stock (CUSIP 55306N104), which the filing states represents 6.2% of the class. The filer reports sole voting power over 4,106,485 shares and sole dispositive power over 4,129,128 shares.

The statement includes the filer’s certification that the securities were acquired and are held in the ordinary course of business and were not acquired to change or influence control of the issuer. The filing lists the issuer address as 2 Tech Drive, Suite 201, Andover, MA, and shows the date of the triggering event as 06/30/2025 with the signature dated 08/14/2025.

Positive

• Reported ownership of 4,129,128 shares (6.2%): a clearly disclosed, material stake in MKS Inc.
• Sole voting and dispositive powers largely held: 4,106,485 shares with sole voting power and 4,129,128 with sole dispositive power provide transparency on control over voting and disposition.
• Certification of ordinary-course holdings: filer states the shares are held in the ordinary course of business and not to influence control.

Negative

• None.

Insights

Investment Adviser

TL;DR T. Rowe Price reports a sizable 6.2% stake in MKS Inc with full voting and dispositive powers on most shares.

The filing documents beneficial ownership of 4,129,128 shares and indicates sole voting power over 4,106,485 shares. The filer explicitly certifies the holdings are held in the ordinary course of business and not to influence control, which clarifies intent under Schedule 13G/A disclosure rules. For portfolio managers, a disclosed >5% position is material for monitoring but the certificate limits interpretation to non-control intent.

Securities Analyst

TL;DR A >5% position by a major adviser is notable disclosure but the filing asserts non-control intent.

The numeric details—4,129,128 shares (6.2%), sole dispositive power over all reported shares, and near-complete sole voting power—are the key takeaways for equity holders and regulators. The document is an amendment to Schedule 13G and includes the filer’s certification that the stake was not acquired to affect control, which limits the market-impact interpretation to informational disclosure rather than an activist signal.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 4)

MKS Inc

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

55306N104

(CUSIP Number)

06/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 55306N104

1

Names of Reporting Persons

T. Rowe Price Associates, Inc.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

MARYLAND

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 4,106,485.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 4,129,128.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

4,129,128.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.2 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MKS Inc
(b)	Address of issuer's principal executive offices: 2 TECH DRIVE, SUITE 201, ANDOVER, MA, 01810
Item 2.
(a)	Name of person filing: T. Rowe Price Associates, Inc.
(b)	Address or principal business office or, if none, residence: 1307 Point Street, Baltimore, MD 21231
(c)	Citizenship: Maryland
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP No.: 55306N104
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 4129128
(b)	Percent of class: 6.2 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 4106485
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 4129128
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. T. Rowe Price Associates, Inc. hereby declares and affirms that the filing of Schedule 13G shall not be construed as an admission that Price Associates is the beneficial owner of the securities referred to, which beneficial ownership is expressly denied.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

T. Rowe Price Associates, Inc.

Signature:	Ellen York
Name/Title:	Vice President
Date:	08/14/2025

FAQ

How many MKS Inc (MKSI) shares does T. Rowe Price report owning?

The filing reports 4,129,128 shares beneficially owned.

What percentage of MKS Inc does that represent?

The reported amount represents 6.2% of the outstanding class.

How much voting and dispositive power does T. Rowe Price have over MKSI shares?

The filer reports sole voting power over 4,106,485 shares and sole dispositive power over 4,129,128 shares.

What type of filing was submitted for MKSI and when is the event date?

An Amendment No. 4 to Schedule 13G was filed, citing the date of the triggering event as 06/30/2025.

Does the filing indicate the shares were acquired to influence control of MKS Inc?

No; the filing contains a certification that the securities were acquired and are held in the ordinary course of business and not to change or influence control.

When was the Schedule 13G/A signed?

The signature block shows the filing was signed on 08/14/2025 by Ellen York, Vice President.