MKSI SEC Filing News — MKS Inc.

Latest SEC filings for MKS Inc. (MKSI) explained in plain English. Covers insider buying and selling (Form 4), proposed insider sales (Form 144), material company events (8-K), and quarterly & annual reports (10-Q / 10-K). StrongBuyAnalytics provides navigation and brief excerpts or summaries; original filings remain at the SEC/source links and were authored by their filers, not StrongBuyAnalytics. Filing dates shown are source dates. Coverage and detection can be delayed or incomplete because of SEC availability, amendments, parsing, caching, or outages. Latest source filing date shown: 2026-09-02.

MKS Inc. provides foundational technology solutions to semiconductor manufacturing, electronics and packaging, and specialty industrial applications in the United States, China, South Korea, Japan, Taiwan, Singapore, and internationally. The company operates through Vacuum Solutions Division (VSD), Photonics Solutions Division (PSD), and Material Solutions Division (MSD) segments. Its VSD segment provides foundational technology solutions, including pressure measurement and control, flow measure…
Sector: Technology Industry: Scientific & Technical Instruments Market Cap: $14.6B CIK: 1049502
20
Total Filings
0
Bullish Classifications
9
Bearish Classifications
10
Insider Transactions
1
Material Events (8-K)
1
Periodic Reports
Rule-based classifications for MKSI currently lean bearish. Of the 20 filing records displayed, 9 carry bearish classifications (such as insider sales or negative 8-K disclosures) versus 0 bullish. This does not necessarily signal fundamental deterioration — insiders sell for many reasons — but it is worth monitoring alongside the company's core financial metrics.
MKSI Filing Activity Snapshot 2026-05-28 — 2026-09-02
Insider Transactions (Form 4)
0 buys vs 9 sells
Net insider selling in this period — insiders sell for many reasons beyond conviction.
Largest Form 144 Filing
$3.02M
Lee John Tseng-Chung (Director, President & CEO) · 2026-08-17
10,000 shares · Form 4
Form 144 Notices
8
Proposed insider sales filed — Form 144 is a notice of intent, not a confirmed transaction. Actual sales are confirmed via Form 4.
Insider Transactions 10 · Forms 3, 4 and 5

A Form 4 is filed within two business days of a company insider — an officer, a director, or a holder of more than ten percent of the stock — changing their position in the shares. All 10 filings in this group are Form 4s for MKS Inc.

The difficulty with reading these filings as a group is that a single form type covers transactions that mean entirely different things. An executive spending their own money to buy stock and an executive having shares withheld to pay tax on a vesting grant both appear as a Form 4. Every filing below is therefore tagged with the nature of the underlying transaction, taken from the transaction code reported on the form itself.

Across the 10 insider filings shown, the breakdown is 9 open-market sale and 1 compensation award. 9 of them involved a discretionary open-market trade; the rest are compensation and administrative mechanics.

What each transaction type means

Open-market sale ×9
The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.
Compensation award ×1
Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.
Form 4 Open-market sale Insider Selling 2026-09-02

MKSI insider Mora Elizabeth (Director) sold 300 shares (~$75.3K)

Mora Elizabeth, listed as Director at MKS INC, reported an open-market sale of 300 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 300 $250.96 $75.3K
Filing: Form 4 (Insider Transaction) Insider: Mora Elizabeth (Director) Shares: 300 Est. Value: $75.3K
View on SEC EDGAR → Open Filing Document →
Form 4 Compensation award Tax / Compensation Filing 2026-08-18

MKSI insider Form 4 filed for equity award, exercise, or tax withholding

Donlan Renee Martel (EVP, GC & CCO) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code Nature Shares Price Value
A Compensation award derivative · Restricted Stock Unit 954 — —
Filing: Form 4 (Insider Transaction) Insider: Donlan Renee Martel (EVP, GC & CCO)
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-17

MKSI insider Lee John Tseng-Chung (Director, President & CEO) sold 10,000 shares (~$3.02M)

Lee John Tseng-Chung, listed as Director, President & CEO at MKS INC, reported an open-market sale of 10,000 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 10,000 $302.01 $3.02M
Filing: Form 4 (Insider Transaction) Insider: Lee John Tseng-Chung (Director, President & CEO) Shares: 10,000 Est. Value: $3.02M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-04

MKSI insider Williams John Edward (EVP & GM, PSD) sold 457 shares (~$131.8K)

Williams John Edward, listed as EVP & GM, PSD at MKS INC, reported an open-market sale of 457 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 457 $288.31 $131.8K
Filing: Form 4 (Insider Transaction) Insider: Williams John Edward (EVP & GM, PSD) Shares: 457 Est. Value: $131.8K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-06-16

MKSI insider Schreiner James Alan (EVP & COO) sold 3,500 shares (~$1.21M)

Schreiner James Alan, listed as EVP & COO at MKS INC, reported an open-market sale of 3,500 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 2,471 $345.52 $853.8K
S Open-market sale 812 $346.41 $281.3K
S Open-market sale 217 $347.00 $75.3K
Filing: Form 4 (Insider Transaction) Insider: Schreiner James Alan (EVP & COO) Shares: 3,500 Est. Value: $1.21M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-06-11

MKSI insider Schreiner James Alan (EVP & COO) sold 781 shares (~$247.9K)

Schreiner James Alan, listed as EVP & COO at MKS INC, reported an open-market sale of 781 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 781 $317.42 $247.9K
Filing: Form 4 (Insider Transaction) Insider: Schreiner James Alan (EVP & COO) Shares: 781 Est. Value: $247.9K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-06-08

MKSI insider McCarthy Michelle M (SVP & Chief Accounting Officer) sold 2,434 shares (~$767.3K)

McCarthy Michelle M, listed as SVP & Chief Accounting Officer at MKS INC, reported an open-market sale of 2,434 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 2,434 $315.23 $767.3K
Filing: Form 4 (Insider Transaction) Insider: McCarthy Michelle M (SVP & Chief Accounting Officer) Shares: 2,434 Est. Value: $767.3K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-06-02

MKSI insider Henry David Philip (EVP, Global Str Mktg & GM, MSD) sold 6,000 shares (~$1.89M)

Henry David Philip, listed as EVP, Global Str Mktg & GM, MSD at MKS INC, reported an open-market sale of 6,000 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 6,000 $314.43 $1.89M
Filing: Form 4 (Insider Transaction) Insider: Henry David Philip (EVP, Global Str Mktg & GM, MSD) Shares: 6,000 Est. Value: $1.89M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-06-02

MKSI insider Mora Elizabeth (Director) sold 300 shares (~$95.4K)

Mora Elizabeth, listed as Director at MKS INC, reported an open-market sale of 300 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 300 $318.02 $95.4K
Filing: Form 4 (Insider Transaction) Insider: Mora Elizabeth (Director) Shares: 300 Est. Value: $95.4K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-05-28

MKSI insider Donahue Joseph B (Director) sold 2,100 shares (~$688.7K)

Donahue Joseph B, listed as Director at MKS INC, reported an open-market sale of 2,100 MKSI shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 2,100 $327.95 $688.7K
Filing: Form 4 (Insider Transaction) Insider: Donahue Joseph B (Director) Shares: 2,100 Est. Value: $688.7K
View on SEC EDGAR → Open Filing Document →
Proposed Insider Sales 8 · Form 144

A Form 144 is a notice of intent to sell restricted or control securities. It is not a record that anything was sold. MKS Inc. has 8 such notices in this period.

The distinction matters because a Form 144 is frequently reported as though it were a completed insider sale. The filer may sell all of the shares covered, some of them, or none at all, and there is no obligation to update the notice either way. A sale that is actually executed by an officer or director shows up separately on a Form 4, which is the filing to check before treating a proposed sale as a real one.

Form 144 Proposed Insider Sale 2026-09-01

MKSI Form 144 filed for proposed insider sale by Mora Elizabeth (300 shares) ~$75.3K

Mora Elizabeth filed a Form 144 with the SEC indicating intent to sell MKSI (MKS INC) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Mora Elizabeth Shares: 300 Est. Value: $75.3K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-14

MKSI Form 144 filed for proposed insider sale by Lee John Tseng-Chung (10,000 shares) ~$3.02M

Lee John Tseng-Chung filed a Form 144 with the SEC indicating intent to sell MKSI (MKS INC) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Lee John Tseng-Chung Shares: 10,000 Est. Value: $3.02M
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-03

MKSI Form 144 filed for proposed insider sale by Williams John Edward (457 shares) ~$131.8K

Williams John Edward filed a Form 144 with the SEC indicating intent to sell MKSI (MKS INC) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Williams John Edward Shares: 457 Est. Value: $131.8K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-06-12

MKSI Form 144 filed for proposed insider sale by Schreiner James Alan (3,500 shares) ~$1.21M

Schreiner James Alan filed a Form 144 with the SEC indicating intent to sell MKSI (MKS INC) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Schreiner James Alan Shares: 3,500 Est. Value: $1.21M
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-06-10

MKSI Form 144 filed for proposed insider sale by Schreiner James Alan (781 shares) ~$247.9K

Schreiner James Alan filed a Form 144 with the SEC indicating intent to sell MKSI (MKS INC) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Schreiner James Alan Shares: 781 Est. Value: $247.9K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-06-05

MKSI Form 144 filed for proposed insider sale by McCarthy Michelle M (2,434 shares) ~$767.3K

McCarthy Michelle M filed a Form 144 with the SEC indicating intent to sell MKSI (MKS INC) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: McCarthy Michelle M Shares: 2,434 Est. Value: $767.3K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-06-01

MKSI Form 144 filed for proposed insider sale by Henry David Philip (6,000 shares) ~$1.89M

Henry David Philip filed a Form 144 with the SEC indicating intent to sell MKSI (MKS INC) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Henry David Philip Shares: 6,000 Est. Value: $1.89M
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-06-01

MKSI Form 144 filed for proposed insider sale by Mora Elizabeth (300 shares) ~$95.4K

Mora Elizabeth filed a Form 144 with the SEC indicating intent to sell MKSI (MKS INC) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Mora Elizabeth Shares: 300 Est. Value: $95.4K
View on SEC EDGAR → Open Filing Document →
Material Events 1 · Form 8-K

An 8-K reports a material event in the window between scheduled reports. There is 1 in this period for MKS Inc. Each 8-K names the item number it is filed under, and that number is the fastest way to tell a routine disclosure from a consequential one.

Item 2.02 is an earnings release, Item 5.02 is a change of directors or officers, and Item 1.01 or 2.01 covers a material agreement or a completed acquisition. Item 7.01 and Item 8.01 are the general-purpose disclosure items and carry no fixed meaning on their own.

Form 8-K Material Company Update 2026-08-05

MKSI filed 8-K — material company event

MKS INC filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)
View on SEC EDGAR → Open Filing Document →
Periodic Reports 1 · Forms 10-K and 10-Q

The periodic reports are where the audited and reviewed financial statements live. This period contains 1 quarterly report (10-Q) for MKS Inc.

The two are not equivalent in weight. A 10-K is audited by an external firm and includes the full risk factor disclosure, business description and management discussion; a 10-Q is unaudited, reviewed rather than examined, and much shorter. When a figure in a quarterly report is later revised, the annual report is usually where the correction appears.

An amended report — 10-K/A or 10-Q/A — restates or corrects something in the original filing, and is worth reading against the version it replaces.

Form 10-Q Quarterly Report 2026-08-06

MKSI filed Quarterly Report (10-Q)

MKS INC filed its quarterly report with the SEC. This report includes unaudited financial statements and management discussion for the quarter.

Filing: 10-Q (Quarterly Report)
View on SEC EDGAR → Open Filing Document →

How we classify MKS Inc.'s filings

Straight from EDGAR

Each displayed record links to an original source document. StrongBuyAnalytics provides navigation and brief excerpts or summaries, not the filing itself. Parsing may omit context or contain errors, so read the original document in full.

Transaction codes, not guesswork

The nature shown on each insider filing comes from the transaction code the filer entered on the form itself — P for an open-market purchase, A for a compensation award, F for shares withheld to pay tax, M for an option exercise. Where one filing contains several codes, the transaction table lists them line by line.

Why the distinction matters

Insider activity is routinely summarised as buying or selling, which flattens together decisions that mean very different things. Shares withheld for tax on a vesting grant are an automatic administrative step; shares bought on the open market are someone committing their own money at the current price.

What this page does not tell you

A filing records what happened, not why. Form 4 does not always disclose whether a sale was executed under a pre-arranged Rule 10b5-1 plan, and no single filing is a basis for a decision on MKSI. Read these alongside the fundamentals rather than in isolation.

Frequently Asked Questions — MKSI SEC Filings

More Tools for MKSI

MKSI Full Stock Analysis MKSI Live Chart Institutional Ownership Earnings Calendar Options Flow Scanner Semiconductor Demand Zone Tracker Sector Scanner Browse All Stocks

Want deeper MKSI analysis?

View valuation, growth metrics, the rule-based stock-page score, demand zones, peer comparison, and more — all on the MKSI stock analysis page.

MKSI Full Analysis
Publisher, sources & limitations — September 15, 2026. StrongBuyAnalytics provides navigation and brief excerpts or summaries for educational use. Original filings remain at SEC EDGAR or other displayed source links; StrongBuyAnalytics does not author them. Filing dates are source dates, not publication dates for this page. Coverage can be delayed, incomplete, amended, or unavailable because of SEC/source availability, parsing, caching, or outages. Verify every material statement in the original filing.
Data Sources · Methodology · AI Disclosure · Corrections Policy · Disclaimer