MKS Inc. director awarded 781 RSUs of common stock

Donahue Joseph B reported acquisition or exercise transactions in this Form 4 filing.

Rhea-AI Filing Summary

Donahue Joseph B reported acquisition or exercise transactions in this Form 4 filing.

MKS Inc. director Joseph B. Donahue received a grant of 781.959 restricted stock units of common stock as compensation. These units vest in full on the day before the first annual meeting of shareholders after the grant date, or on the 13‑month anniversary if no meeting occurs. After this award, Donahue directly holds a total of 12,132.704 shares of MKS common stock, assuming settlement of vested units in shares. Each restricted stock unit represents the right to receive one share of MKS Inc. common stock when it vests, so this filing reflects equity-based compensation rather than an open-market purchase.

Insider Trade Summary

Grant/Award: 781.959 shares

Grant/Award 1 txn

Insider Donahue Joseph B

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	781.959	$0.00	$0.00

Holdings After Transaction: Common Stock — 12,132.704 shares (Direct)

Footnotes (2)

1. F1. These restricted stock units become fully vested on the day prior to the first annual meeting of shareholders following the date of grant (or if no such meeting is held within 13 months after the date of grant, on the 13 month anniversary of the date of grant).
2. F2. Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Inc.

Key Figures

RSU grant size: 781.959 units Post-transaction holdings: 12,132.704 shares RSU-to-share ratio: 1 unit : 1 share

3 metrics

RSU grant size 781.959 units Restricted stock units of common stock granted to director

Post-transaction holdings 12,132.704 shares Common stock held directly after the award

RSU-to-share ratio 1 unit : 1 share Each RSU represents right to one MKS Inc. share

Key Terms

restricted stock units, contingent right, annual meeting of shareholders

3 terms

restricted stock units financial

"These restricted stock units become fully vested on the day prior to the first annual meeting of shareholders following the date of grant"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

contingent right financial

"Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Inc."

annual meeting of shareholders financial

"day prior to the first annual meeting of shareholders following the date of grant"

A yearly gathering where a company’s owners (shareholders) vote on key items like electing the board, approving executive pay, and ratifying auditors, and receive updates on performance and strategy. Think of it as an annual town hall for owners: it matters to investors because outcomes and disclosures can affect leadership, corporate direction, dividend and governance policies, and therefore the company’s risk and potential return.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did MKS Inc. director Joseph B. Donahue report in this Form 4 for MKSI?

Joseph B. Donahue reported receiving 781.959 restricted stock units of MKS Inc. common stock as a compensation-related grant. Each unit represents a right to receive one share of common stock upon vesting, rather than an open-market stock purchase or sale.

How many MKS Inc. shares does Joseph B. Donahue hold after this Form 4 transaction?

After this grant, Joseph B. Donahue is shown holding 12,132.704 shares of MKS Inc. common stock directly. This figure reflects his position following the award and provides context for the relative size of the 781.959-unit restricted stock grant.

Is the MKS Inc. (MKSI) Form 4 transaction an open-market buy or sale?

The Form 4 shows a grant of restricted stock units, not an open-market buy or sale. The transaction is coded as an acquisition (grant/award), indicating equity compensation awarded to director Joseph B. Donahue rather than a discretionary market trade.

When do Joseph B. Donahue’s restricted stock units in MKS Inc. vest?

The restricted stock units become fully vested on the day before the first annual meeting of shareholders after the grant date. If no meeting occurs within 13 months, they vest on the 13‑month anniversary, according to the footnote terms in the filing.

What does each restricted stock unit in this MKS Inc. Form 4 represent?

Each restricted stock unit represents a contingent right to receive one share of MKS Inc. common stock. The units convert into shares once vesting conditions are met, so they function as deferred equity compensation rather than currently tradable shares.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/12/2026 - 03:07 PM EDT Learn about SEC filing dates

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^*

Donahue Joseph B

(Last) (First) (Middle)

C/O MKS INC.

2 TECH DRIVE

(Street)

ANDOVER MASSACHUSETTS 01810

(City) (State) (Zip)

UNITED STATES

(Country)

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

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/11/2026

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

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

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

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	05/11/2026		A(1)		781.959	A	(2)	12,132.704	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. These restricted stock units become fully vested on the day prior to the first annual meeting of shareholders following the date of grant (or if no such meeting is held within 13 months after the date of grant, on the 13 month anniversary of the date of grant).

2. Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Inc.

	/s/ M. Kathryn Rickards, attorney-in-fact	05/12/2026
	** 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.
* Form 4: SEC 1474 (03-26)