MKSI Form 144: Proposed sale of common stock

MKSI submitted a Form 144 notice reporting a proposed sale of common stock by an affiliate.

Rhea-AI Filing Summary

MKSI submitted a Form 144 notice reporting a proposed sale of common stock by an affiliate. The filing lists multiple plan-originated grants and vesting events and shows a recent disposition of 781 shares on 06/10/2026 for $247,905.02.

Insights

Securities Counsel

Form 144 notifies regulators of an affiliate's intended sale; reported past sale is an executed disposition.

The filing lists plan-originated issuances (ESPP purchases and restricted stock vesting) and includes a concrete past sale: $247,905.02 for 781 shares on 06/10/2026. This identifies the affiliate's recent market activity.

Timing and aggregate proposed sale amounts are not provided in the excerpt; cash‑flow treatment for future sales and any broker or distribution methods are not specified in the provided text.

Key Figures

Recent sale: 781 shares Proceeds shown: $247,905.02 ESPP purchase example: 83 shares +2 more

5 metrics

Recent sale 781 shares sale date <date>06/10/2026</date>

Proceeds shown $247,905.02 gross amount for 781-share sale on <date>06/10/2026</date>

ESPP purchase example 83 shares ESPP purchase dated <date>05/28/2021</date>

Restricted stock vesting examples 980; 1,105; 1,260 shares vesting dates <date>09/16/2021</date>, <date>02/15/2022</date>, <date>02/15/2024</date>

Brokerage account reference 3,500 (appears) line showing Fidelity Brokerage Services LLC with number 3500

Key Terms

Form 144, ESPP Purchase, Restricted Stock Vesting, Issuer

4 terms

Form 144 regulatory

"144: Securities To Be Sold"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

ESPP Purchase financial

"05/28/2021 | ESPP Purchase | Issuer"

Restricted Stock Vesting financial

"09/16/2021 | Restricted Stock Vesting | Issuer"

Restricted stock vesting is the timetable and conditions under which shares granted to employees or insiders become fully owned and can be sold, typically requiring continued work or meeting performance goals. It matters to investors because large blocks of shares can become tradable at once, which can change share supply and price, and because vesting aligns insiders’ incentives with the company’s long‑term performance—think of it like a timed unlock that both rewards and locks in key people.

Issuer regulatory

"ESPP Purchase | Issuer"

FAQ

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

What does MKSI's Form 144 report?

The Form 144 notifies the SEC of a proposed sale of MKSI common stock by an affiliate. The excerpt lists plan grants and a past disposition of 781 shares on 06/10/2026 for $247,905.02, which is recorded as a recent sale.

How many shares were sold recently according to the filing for MKSI?

The filing records a past sale of 781 shares on 06/10/2026. The transaction is shown with a gross amount of $247,905.02 in the extracted content and appears under "Securities Sold During The Past 3 Months."

Does the Form 144 show total shares being registered for sale for MKSI?

The provided excerpt does not state an aggregate registered offering amount. It lists multiple grant and vesting events and a single recent sale of 781 shares; no total proposed-sale aggregate is shown in the excerpt.

What types of share issuances are listed in the MKSI excerpt?

The excerpt lists ESPP purchases and multiple restricted stock vesting events with share counts (for example, 83; 980; 72; 1,105; 1,260). These entries are shown with their respective grant or vesting dates in the filing.

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

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Accepted by SEC EDGAR 06/12/2026 - 11:06 AM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001797189
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	MKS INC
SEC File Number	000-23621
Address of Issuer	2 TECH DRIVE ANDOVER MASSACHUSETTS 01810
Phone	978-645-5500
Name of Person for Whose Account the Securities are To Be Sold	Schreiner James Alan
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917	3500	1210370.16	67544129	06/12/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	05/28/2021	ESPP Purchase	Issuer			83	05/28/2021	Cash
Common	09/16/2021	Restricted Stock Vesting	Issuer			980	09/16/2021	Compensation
Common	11/30/2021	ESPP Purchase	Issuer			72	11/30/2021	Cash
Common	02/15/2022	Restricted Stock Vesting	Issuer			1105	02/15/2022	Compensation
Common	02/15/2024	Restricted Stock Vesting	Issuer			1260	02/15/2024	Compensation

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
James Schreiner 2 Tech Drive Andover MA 01810	Common	06/10/2026	781	247905.02

144: Remarks and Signature

Remarks
Date of Notice	06/12/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Emily Navaro, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for James Schreiner.
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)