UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM SD

SPECIALIZED DISCLOSURE REPORT

MKS Instruments, Inc.

(Exact name of the registrant as specified in its charter)

Kathleen F. Burke (978) 645-5574

(Name and telephone number, including area code, of the person to contact in connection with this report.)

Check the appropriate box to indicate the rule pursuant to which this form is being filed, and provide the period to which the information in this form applies:

Section 1 – Conflict Minerals Disclosure

Item 1.01 – Conflict Minerals Disclosure and Report

Conflict Minerals Disclosure

MKS Instruments, Inc. (“MKS” or the “Company”) has determined that gold, columbite-tantalite (coltan), cassiterite and wolframite, including their derivatives, tantalum, tin and tungsten (“Conflict Minerals”), are necessary to the functionality or production of products manufactured or contracted to be manufactured by MKS.

MKS conducted in good faith a country of origin inquiry regarding Conflict Minerals in its products which was reasonably designed to determine if any of the Conflict Minerals originated in the Democratic Republic of the Congo or an adjoining country (“Covered Countries”), or from recycled or scrap sources.

MKS has determined that it is required to file, and has filed, a Conflict Minerals Report describing its reasonable country of origin inquiry and due diligence efforts on the source and chain of custody of the Conflict Minerals in its products. The Conflict Minerals Report is provided as Exhibit 1.01 to this Form SD and is publicly available on MKS’ website at https://www.mks.com/ConflictMineralsReport.

Item 1.02 – Exhibit

MKS’ Conflict Minerals Report for the calendar year ended December 31, 2023 is filed as Exhibit 1.01 to this Form SD.

Section 2 – Resource Extraction Issuer Disclosure

Item 2.01 – Resource Extraction Issuer Disclosure and Report

Not Applicable

Section 3 – Exhibits

Item 3.01 – Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the duly authorized undersigned.

Exhibit 1.01

MKS INSTRUMENTS, INC.

Conflict Minerals Report

For the Year Ended December 31, 2023

Special Note Regarding Forward-Looking Statements

This report contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). These forward-looking statements reflect management’s current opinions and are subject to certain risks and uncertainties that could cause actual results to differ materially from those stated. MKS assumes no obligation to update this information. Risks and uncertainties include, but are not limited to, those discussed in the section entitled “Risk Factors” found in the Company’s most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q, as filed with the Securities and Exchange Commission (the “SEC”).

Summary of the Conflict Minerals Rule

This report for the year ended December 31, 2023 is included to comply with Rule 13p-1 under the Exchange Act (the “Conflict Minerals Rule”), which was adopted by the SEC to implement reporting and disclosure requirements related to Conflict Minerals as directed by the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010. The Conflict Minerals Rule imposes certain reporting obligations on a company that files reports with the SEC under Sections 13(a) and 15(d) of the Exchange Act (a “public company”), whose manufactured products contain Conflict Minerals which are necessary to the functionality or production of its products. Conflict minerals are defined as gold, columbite-tantalite (“coltan”), cassiterite and wolframite, including their derivatives, tantalum, tin and tungsten (“Conflict Minerals”).

If a public company cannot establish that the Conflict Minerals originated from sources other than the Democratic Republic of the Congo or an adjoining country (the “Covered Countries”), or from recycled and scrap sources, it must submit a Form SD which describes the reasonable country of origin inquiry completed.

If a public company has reason to believe that any of the Conflict Minerals in its supply chain may have originated in the Covered Countries, or if it is unable to determine the country of origin of those Conflict Minerals, then that company must exercise due diligence on the Conflict Minerals’ source and chain of custody. The company must annually submit a report to the SEC that includes a description of those due diligence measures (“Conflict Minerals Report”).

This report has been prepared by management of MKS Instruments, Inc. (herein referred to as “MKS,” the “Company,” “we,” “us,” or “our”). The information in this report includes the activities of MKS and its subsidiaries.

Founded in 1961, MKS enables technologies that transform our world. MKS delivers foundational technology solutions to leading edge semiconductor manufacturing, electronics and packaging, and specialty industrial applications. MKS applies its broad science and engineering capabilities to create instruments, subsystems, systems, process control solutions and specialty chemicals technology that improve process performance, optimize productivity and enable unique innovations for many of the world’s leading technology and industrial companies. MKS’ solutions are critical to addressing the challenges of miniaturization and complexity in advanced device manufacturing by enabling increased power, speed, feature enhancement, and optimized connectivity. MKS’ solutions are also critical to addressing ever-increasing performance requirements across a wide array of specialty industrial applications. MKS employs approximately 10,000 individuals.

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MKS has three reportable segments: the Vacuum Solutions Division (“VSD”) segment, the Photonics Solutions Division (“PSD”) segment and the Materials Solutions Division (“MSD”) segment. The VSD segment delivers foundational technology solutions to leading edge semiconductor manufacturing, electronics and packaging and specialty industrial applications. VSD products are derived from MKS’ core competencies in pressure measurement and control, flow measurement and control, gas and vapor delivery, gas composition analysis, electronic control technology, reactive gas generation and delivery, power generation and delivery and vacuum technology. The PSD segment provides a broad range of instruments, components and subsystems to leading edge semiconductor manufacturing, electronics and packaging and specialty industrial applications. PSD products are derived from MKS’ core competencies in lasers, photonics, optics, temperature sensing, precision motion control and vibration control. The MSD segment develops leading process and manufacturing technologies for advanced surface modification, electroless and electrolytic plating, and surface finishing. Applying a comprehensive systems-and-solutions approach, MSD’s portfolio includes chemistry, equipment, software, and services for innovative and high-technology applications in our electronics and packaging and specialty industrial markets.

MKS has tens of thousands of products in its portfolio. MKS’ products are used in diverse markets, applications and processes. MKS serves the semiconductor, electronics and packaging, and specialty industrial markets.

Semiconductor Market

We are a critical solutions provider for semiconductor manufacturing. Our products are used in major semiconductor processing steps, such as deposition, etching, cleaning, lithography, metrology, and inspection. The semiconductor industry continually faces new challenges, as products become smaller, more powerful and highly mobile. Ultra-thin layers, smaller critical dimensions, new materials, 3D structures, and the ongoing need for higher yield and productivity drive the need for tighter process measurement and control, all of which MKS supports. We believe we are the broadest critical subsystem provider in the wafer fabrication equipment ecosystem and address over 85% of the market. We have characterized our broad and unique offering as Surround the Wafer^® to reflect the technology enablement we provide across almost every major process in semiconductor manufacturing today.

Electronics and Packaging Market

MKS is a foundational solutions provider for the electronics and packaging market. Our portfolio includes photonics components, laser drilling systems, electronics chemistries and plating equipment that are critical for the manufacturing of printed circuit boards (“PCBs”) and package substrates, and critical to wafer level packaging (“WLP”) applications. Similar to the semiconductor industry, the PCB, package substrate and WLP industries increasingly demand smaller features, greater density, and better performance. In addition, the electronics and packaging market also includes sales of our vacuum and photonics solutions for display manufacturing applications. We characterize our complementary offering of laser systems and chemistry solutions as Optimize the Interconnect^®, to reflect the unique technology enablement we provide at the interconnect level within PCBs, package substrates and WLPs.

Specialty Industrial Market

MKS’ strategy in specialty industrial is to leverage our domain expertise and proprietary technologies across a broad array of applications in industrial technologies, life and health sciences, and research and defense markets. Industrial technologies encompasses a wide range of diverse applications, including chemistries for functional coatings, surface finishing and wear resistance in the automobile industry, vacuum solutions for synthetic diamond manufacturing and photonics for solar manufacturing. Other applications include vacuum and photonics solutions for light emitting diode and laser diode manufacturing. Our products for life and health sciences are used in a diverse array of applications, including bioimaging, medical instrument sterilization, medical device manufacturing, analytical, diagnostic and surgical instrumentation, consumable medical supply manufacturing and pharmaceutical production. Our products for research and defense are sold to government, university and industrial laboratories for applications involving research and development in materials science, physical chemistry, photonics, optics and electronics materials. Our products are also sold for monitoring and defense applications including surveillance, imaging and infrastructure protection.

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Except for certain specific product lines (e.g. fittings, flanges, lenses, certain mirrors, tubing, certain chemistry products, etc.), many of the products MKS manufactures or contracts to manufacture include tin, gold, tantalum and/or tungsten. Additionally, MSD sells chemical solutions that themselves directly contain gold and tin (e.g. Aurotech^® and Stannatech^® products). As a result, Conflict Minerals are found in many MKS products.

Supply Chain

With such an extensive product portfolio, our supply chain is highly complex. In 2023, MKS and its subsidiaries purchased supplies from over 4,600 suppliers across the world. In addition to dealing with a very large number of suppliers, MKS deals with multiple tiers of suppliers. We are generally many steps removed from the mining of Conflict Minerals and the smelting and refining of raw ores. We do not buy raw ore or unrefined Conflict Minerals or make purchases from the Covered Countries. Except with respect to one supplier of gold that is also a smelter, we do not buy directly from smelters or refiners. The smelters and refiners are in the best position in our supply chain to know the origin of the ores. For these reasons, the process of mapping our end-to-end supply chain is extremely onerous.

In order to comply with the Conflict Minerals Rule, we rely on our direct suppliers to provide information on the origin of the Conflict Minerals contained in components and materials supplied to us, including sources of Conflict Minerals that are supplied to them from lower tier suppliers. Our outreach efforts for the past ten years are summarized below:

Despite having conducted a good faith reasonable country of origin inquiry, we are unable to determine the origin of all of the Conflict Minerals in our products. Due to the complexity of our broad product portfolio and supply chain, it will take additional time for many of our suppliers to verify the origin of the Conflict Minerals in the products they supply to us. We continue to engage with each of these suppliers and they in turn continue to engage with their suppliers. We hope that with additional time, these outreach efforts will result in greater transparency into

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our supply chain. In addition, Assent Compliance confirmed that certain Conflict Minerals in our products likely originated in the Covered Countries. For these reasons, we are required under the Conflict Minerals Rule to submit to the SEC a Conflict Minerals Report as an exhibit to Form SD. This report must include:

In accordance with The Organisation for Economic Co-operation and Development (OECD) Guidance and the Conflict Minerals Rule, this report is available on our website https://www.mks.com/ConflictMineralsReport.

Conflict Minerals Policy

We adopted the following Conflict Minerals Policy:

MKS Conflict Minerals Policy

In 2012, the U.S. Securities and Exchange Commission (the “SEC”) issued its final rule under Section 1502 of the 2010 Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Conflict Minerals Rule”) imposing new disclosure and related supply chain due diligence requirements for public companies regarding their use of “Conflict Minerals” in products they manufacture or contract to manufacture. The goal of this new rule is to curb the violent conflict and human rights abuses in the Democratic Republic of the Congo (“DRC”)¹ and adjoining countries that are being financed in part by the exploitation and trade of Conflict Minerals from that region.

The Conflict Minerals Rule defines “Conflict Minerals” as cassiterite (tin), columbite-tantalite (tantalum), wolframite (tungsten), their respective derivatives and gold (commonly referred to as the “3Ts&G”). MKS, being a global provider of instruments, systems, subsystems and process control solutions that measure, monitor, deliver, analyze, power and control critical parameters of advanced manufacturing processes to improve process performance and productivity for its customers, uses certain of these Conflict Minerals in the manufacturing of its products. MKS is committed to identifying any of its suppliers who source Conflict Minerals from the DRC region from conflict sources. We expect our suppliers to partner with us in this endeavor regardless of whether they are subject to the new Conflict Minerals Rule by providing us with all necessary declarations. We also expect our suppliers to pass this requirement on to their supply chain if they do not source directly from smelters, to determine the source of the Conflict Minerals. The process of mapping our end-to-end supply chain is onerous because MKS deals with multiple tiers and a very large number of suppliers. However, MKS is committed to this effort and should MKS discover at any time that any of its suppliers are sourcing materials from the DRC region from conflict sources, MKS will work with the supplier to end this practice and if the supplier refuses, MKS will work diligently to identify and partner with an alternative supplier.

If you have any questions regarding MKS’ Policy on Conflict Minerals, please contact us at conflictminerals_customer@mksinst.com.

MKS’ relevant Conflict Minerals Report can be found at https://www.mks.com/ConflictMineralsReport.

Our policy is publicly available on our website at https://www.mks.com/ConflictMineralsPolicy.

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Our due diligence process has been designed to conform generally with the framework in the OECD Due Diligence Guidance for Responsible Supply Chains of Minerals from Conflict-Affected and High-Risk Areas (OECD Guidance) and the related Supplements for gold and for tin, tantalum and tungsten.

Our due diligence process includes:

As described above, MKS has adopted a company policy which is posted on our website at https://www.mks.com/ConflictMineralsPolicy.

Internal Team

MKS has established a cross-functional team led by our Global Supply Chain Manager, who has 20 years of experience in chemical and supplier management. The team is responsible for implementing our Conflict Minerals compliance strategy. Senior management is briefed about the results of our due diligence efforts.

Supplier Engagement

With respect to the OECD requirement to strengthen engagement with suppliers, we have established, where practicable, long-term relationships with our numerous suppliers. We have communicated to our suppliers our expectations with respect to the Conflict Minerals Rule. In addition, we have incorporated our expectations with respect to our Conflict Mineral Policy and reporting obligation into the terms and conditions of our supplier contracts.

Maintain Records

We have developed an internal system for documenting the implementation, management and monitoring of our Conflict Minerals Program.

Because of our size, the complexity of our products, and the depth and breadth of our supply chain, it is difficult to identify suppliers upstream from our direct suppliers. In 2023, either directly or through our third-party service provider, Assent Compliance, we reached out to all of our direct suppliers for Relevant Products, representing 100% of our supplier spend for Relevant Products. We rely on these suppliers, whose components and materials contain Conflict Minerals, to provide us with information about the source of Conflict Minerals contained in the components and materials supplied to us. Our direct suppliers are similarly reliant upon information provided by their suppliers. Many of our direct suppliers and distributors either: (i) provided names of smelters or refiners that could not be verified using the Responsible Minerals Assurance Process Conformant Smelters & Refiners Lists, (ii) did not respond to our survey despite follow-up requests, (iii) responded to our survey with incomplete or inconsistent information, or (iv) responded to our survey with a form letter informing us that they would not be

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completing the survey due to a variety of reasons, including, but not limited to: (a) lack of resources, (b) the fact that only de minimis amounts of Conflict Minerals were contained in their products, and/or (c) the supplier was not itself subject to the Conflict Minerals Rule. In general, follow-up requests to these suppliers did not produce additional information unless we had leverage with a particular supplier due to the amount of our spend with such supplier. More time is still needed to determine all of the smelters/refiners used in our supply chain. MKS plans to continue its efforts to identify all of the Conflict Minerals’ smelters/refiners used in our supply chain through a combination of annual supplier surveys and direct follow-up supplier engagement.

MKS has a risk management plan through which the Conflict Minerals program is implemented, managed and monitored. Updates to this risk assessment are provided to senior management.

As part of our risk management plan, to ensure suppliers understand our expectations, in addition to the Conflict Minerals Policy that we publish on our website, we incorporate our expectations with respect to our Conflict Mineral Policy into the terms and conditions of our supplier contracts. Either directly or through our third-party service provider, Assent Compliance, we also requested information from our suppliers who represent 100% of our 2023 supplier spend for Relevant Products, and both Assent Compliance and MKS held individual follow-up calls with and/or sent emails to those suppliers whose survey responses were incomplete, unclear or seemed erroneous based on our knowledge of the materials we purchase from that supplier.

As described in our Conflict Minerals Policy, we will work with any of our suppliers whom we have reason to believe is supplying us with Conflict Minerals from sources that may support conflict in the DRC or any adjoining country to end this practice and if the supplier refuses, we will work diligently to identify and partner with an alternative supplier of Conflict Minerals that does not support such conflict.

Except with respect to one supplier of gold that is also a smelter, we do not have a direct relationship with Conflict Minerals smelters and refiners. We do not perform or direct audits of these entities within our supply chain. We rely on audits performed by industry groups like the Responsible Business Alliance’s Responsible Minerals Initiative.

This report is available on our website at https://www.mks.com/ConflictMineralsReport.

Request Information

We conducted a survey of those suppliers described above using the Responsible Minerals Initiative template, known as the Conflict Minerals Reporting Template. The template was developed to facilitate disclosure and communication of information regarding smelters that provide material to a company’s supply chain. It includes questions regarding a company’s Conflict Minerals policy, engagement with its direct suppliers, and a listing of the smelters the company and its suppliers use. In addition, the template contains questions about the origin of Conflict Minerals included in their products.

Survey Responses

Either directly or through our third-party service provider, Assent Compliance, we received responses from 72% of our worldwide suppliers (including 100% of our suppliers of Relevant Chemistry Products), representing 93% of our total supplier spend. We reviewed the responses against criteria developed to determine which required further engagement with our suppliers. The vast majority of our suppliers provided data at a company level (vs. a product level). In many of the responses received, (i) the responses were incomplete and/or contained

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inconsistencies within the data reported in the template and (ii) the identities of the smelters or refiners were not known. We continue to engage directly with these suppliers to provide revised or missing information. We are therefore not yet in a position to verify that all of the smelters or refiners in our supply chain are certified as conflict-free by the Responsible Business Alliance.

Efforts to Determine Mine or Location of Origin

In our supplier survey, we requested our suppliers to identify the smelter or refiner used in their respective supply chain. We have determined that seeking information about Conflict Minerals’ smelters and refiners in our supply chain represents the most reasonable effort we can make to determine the mines or locations of origin of the Conflict Minerals in our supply chain. Based on the information provided by MKS suppliers in 2023, Exhibit A includes 355 smelters and refiners used in our supply chain that were identified by Responsible Minerals Initiative as “Conformant,” “Active,” or “Known.” “Conformant” smelters and refiners are those smelters and refiners that have undergone a third-party audit, have systems in place to assure sourcing of only DRC conflict free materials, and are therefore identified as “Conformant” with Responsible Minerals Initiative’s Process Assessment Program. “Active” smelters are those that have agreed in writing to produce information and are actively progressing towards a third-party audit. “Known” smelters and refiners are known to Responsible Minerals Initiative but not currently classified as “Conformant” or “Active.” Despite our due diligence efforts, we know this list is incomplete as several of our suppliers either did not return a completed survey or returned an incomplete survey which did not include smelter or refiner names. We expect that with more time, more upstream suppliers will be in a better position to identify relevant smelters and refiners and will in turn pass that information further down the supply chain so that this list will be more complete.

To date, we have been informed that five of the smelters identified by our suppliers are located in Covered Countries but with further due diligence, we confirmed that all are on the Responsible Minerals Assurance Process Known Smelters & Refiners Lists. We are not aware of any other instance where we have reason to believe any of our suppliers are supplying us with Conflict Minerals from a source that may support conflict in the DRC or any adjoining country.

We intend to take the following steps in 2024 to expand and improve the due diligence conducted with respect to our supply chain:

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EXHIBIT A