Dear CMC Materials, Inc. Stockholder:

You are cordially invited to attend a special meeting of stockholders of CMC Materials, Inc., a Delaware corporation, which is referred to as CMC, to be held on March 3, 2022, virtually via the Internet at www.virtualshareholdermeeting.com/CCMP2022SM, at 8 a.m. Central Standard Time, which, including any adjournments or postponements thereof, is referred to as the special meeting. The purpose of the special meeting is to consider and vote on proposals relating to the proposed acquisition of CMC by Entegris, Inc., a Delaware corporation, which is referred to as Entegris. The acquisition will create a leader in electronic materials with a comprehensive electronic materials platform resulting from the addition of CMC’s leading Chemical Mechanical Planarization (“CMP”) and other products and technology to Entegris’ word-class solution set.

On December 14, 2021, Entegris, Yosemite Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Entegris, which is referred to as Merger Sub, and CMC, entered into an Agreement and Plan of Merger, which, as it may be amended from time to time, is referred to as the merger agreement, pursuant to which Entegris agreed to acquire CMC in a cash and stock transaction. Pursuant to the terms of the merger agreement, Merger Sub will merge with and into CMC, which transaction is referred to as the merger, with CMC surviving the merger as a wholly owned subsidiary of Entegris.

Upon successful completion of the merger, each issued and outstanding share of CMC common stock will be converted into the right to receive (i) $133.00 in cash, which amount is referred to as the cash consideration, and (ii) 0.4506 shares of Entegris common stock, which number is referred to as the exchange ratio, plus cash in lieu of any fractional shares. Clauses (i) and (ii) are collectively referred to as the merger consideration. The exchange ratio is fixed and will not be adjusted for changes in the market price of either Entegris common stock or CMC common stock between the dates of signing of the merger agreement and completion of the merger. Based on the closing price of Entegris common stock on the Nasdaq Global Select Market, which is referred to as the NASDAQ, on December 14, 2021, the last trading day before public announcement of the merger, of $143.22, the merger consideration represented approximately $197.53 in value for each share of CMC common stock. Based on the closing price of Entegris common stock on the NASDAQ on January 25, 2022, the last practicable trading day before the date of the accompanying proxy statement/prospectus, of $116.24, the merger consideration represented approximately $185.38 in value for each share of CMC common stock. The value of Entegris common stock at the time of completion of the merger could be greater than, less than or the same as the value of Entegris common stock on the date of the accompanying proxy statement/prospectus. We urge you to obtain current market quotations of Entegris common stock (trading symbol “ENTG”) and CMC common stock (trading symbol “CCMP”).

Based on (i) the estimated number of shares of Entegris common stock and CMC common stock issued and outstanding at the close of business on January 25, 2022, the latest practicable date before the date of this proxy statement/prospectus and (ii) the estimated number of shares of Entegris common stock issuable upon the exercise of any converted options, it is expected that CMC stockholders will own approximately 9% of the issued and outstanding shares of Entegris immediately following the completion of the merger. At the special meeting, CMC stockholders will be asked to consider and vote on (1) the proposal to adopt the merger agreement, which proposal is referred to as the merger agreement proposal, (2) the proposal to approve, on a non-binding advisory basis, specific compensatory arrangements between CMC and its named executive officers relating to the merger, which proposal is referred to as the compensation proposal and (3) the proposal to adjourn the special meeting to solicit additional proxies if there are not sufficient votes to approve the merger agreement proposal or to ensure that any supplement or amendment to the accompanying proxy statement/prospectus is timely provided to CMC stockholders, which proposal is referred to as the adjournment proposal. The board of directors of CMC unanimously recommends that CMC stockholders vote “FOR” each of the proposals to be considered at the special meeting.

Your vote is important. Whether or not you plan to attend the special meeting and regardless of the number of shares you own, your careful consideration of, and vote on, the proposal to adopt the merger agreement is important, and you are encouraged to vote promptly. The merger cannot be completed unless the merger agreement is adopted by stockholders holding a majority of the outstanding shares of CMC’s common stock entitled to vote on such matter. The failure to vote will have the same effect as a vote “AGAINST” the proposal to adopt the merger agreement.

The accompanying proxy statement/prospectus provides you with important information about the special meeting, the merger, and each of the proposals. We encourage you to read the entire document carefully, in particular the “Risk Factors” section beginning on page 27 for a discussion of risks relevant to the merger.

After reading the accompanying proxy statement/prospectus, please make sure to vote your shares promptly by completing, signing and dating the accompanying proxy card and returning it in the enclosed prepaid envelope or by voting by telephone or through the Internet by following the instructions on the accompanying proxy card. If you hold shares through an account with a bank, broker, trust or other nominee, please follow the instructions you receive from it to vote your shares.

Thank you in advance for your continued support and your consideration of this matter. We look forward to the successful completion of the merger.

Sincerely,

 

President and Chief Executive Officer

CMC Materials, Inc.

Neither the U.S. Securities and Exchange Commission nor any state securities commission has approved or disapproved of the merger or the Entegris common stock to be issued in the merger or determined if this proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

The accompanying notice of special meeting of stockholders and proxy statement/prospectus are dated January 28, 2022 and are first being mailed to the stockholders of CMC on or about January 28, 2022.

 

To the Stockholders of CMC Materials, Inc.:

On December 14, 2021, CMC Materials, Inc., which is referred to as CMC, and Entegris, Inc., which is referred to as Entegris, entered into an Agreement and Plan of Merger, which, as it may be amended from time to time, is referred to as the merger agreement, a copy of which is attached as Annex A to the accompanying proxy statement/prospectus.

NOTICE IS HEREBY GIVEN that a special meeting of holders of CMC common stock, which is referred to as the special meeting, will be held on March 3, 2022, virtually via the Internet at www.virtualshareholdermeeting.com/CCMP2022SM, at 8 a.m., Central Standard Time. In light of the ongoing developments related to the COVID-19 pandemic and to protect the health of CMC’s stockholders and the community, the special meeting will be held in a virtual-only format conducted via live audio webcast. You will be able to attend the special meeting by visiting www.virtualshareholdermeeting.com/CCMP2022SM, which is referred to as the special meeting website, and inserting the 16-digit control number included in your proxy card or voting instruction form provided by your bank, broker, trustee, nominee or other holder of record if you hold your shares of CMC common stock through an account with a bank, broker, trust or other nominee. You will be able to vote your shares electronically over the Internet and submit questions online during the meeting by logging onto the website listed above and using the control number. We are pleased to notify you of and invite you to the special meeting.

At the special meeting you will be asked to consider and vote on the following proposals:

CMC will transact no other business at the special meeting except such business as may properly be brought before the special meeting or any adjournment or postponement thereof. The accompanying proxy statement/prospectus, including the merger agreement attached thereto as Annex A, contains further information with respect to these matters.

Only holders of record of CMC common stock at the close of business on January 25, 2022, the record date for voting at the special meeting, which is referred to as the record date, are entitled to notice of and to vote at the special meeting and any adjournments or postponements thereof.

The board of directors of CMC, which is referred to as the CMC board of directors, has unanimously approved and declared advisable the merger agreement and the transactions contemplated by the merger agreement, including the merger, on the terms and subject to the conditions set forth in the merger agreement. The CMC board of directors unanimously recommends that CMC stockholders vote “FOR” the merger agreement proposal, “FOR” the compensation proposal and “FOR” the adjournment proposal.

Your vote is very important, regardless of the number of shares of CMC common stock you own. The merger cannot be completed unless the merger agreement is adopted by stockholders holding a majority of the outstanding shares of CMC’s common stock entitled to vote on such matters. Assuming a quorum is present, the approval of the merger agreement proposal requires the affirmative vote of a majority of the outstanding shares of CMC common stock entitled to vote on the merger agreement proposal.

Whether or not you plan to attend the special meeting via the special meeting website, we urge you to please promptly complete, sign, date and return the accompanying proxy card in the enclosed postage-paid envelope or authorize the individuals named on the accompanying proxy card to vote your shares by calling the toll-free telephone number or by using the Internet as described in the instructions included with the accompanying proxy card. If your shares are held in the name of a bank, broker, trustee or other nominee, please follow the instructions on the voting instruction card furnished by such bank, broker, trustee or other nominee.

If you have any questions about the merger, please contact CMC at (630) 499-2600 or write to CMC, Attn: Corporate Secretary, 870 North Commons Drive, Aurora, Illinois 60504.

If you have any questions about how to vote or direct a vote in respect of your shares of CMC common stock, you may contact CMC’s proxy solicitor, Innisfree M&A Incorporated, toll-free at (877) 750-8334 or call collect at (212) 750-5833.

By Order of the CMC Board of Directors,

 

William P. Noglows

Chairman of the Board

Aurora, Illinois

Dated: January 28, 2022

This proxy statement/prospectus incorporates important business and financial information about Entegris and CMC from other documents that Entegris and CMC have filed with the U.S. Securities and Exchange Commission, which is referred to as the SEC, and that are contained in or incorporated by reference into this proxy statement/prospectus. For a listing of documents incorporated by reference into this proxy statement/prospectus, please see the section entitled “Where You Can Find More Information” beginning on page 169. This information is available for you free of charge to review through the SEC’s website at www.sec.gov.

You may request copies of this proxy statement/prospectus and any of the documents incorporated by reference into this proxy statement/prospectus or other information, without charge, by telephone or written request directed to:

 Innisfree M&A Incorporated

501 Madison Avenue, 20th Floor

New York, New York 10022

Toll-Free: (877) 750-8334

Call Collect: (212) 750-5833

In order for CMC stockholders to receive timely delivery of the documents in advance of the special meeting of CMC stockholders to be held on March 3, 2022, which is referred to as the special meeting, you must request the information from CMC no later than February 24, 2022, which is the date that is five business days before the date of the special meeting.

The contents of the websites of the SEC, Entegris, CMC or any other entity are not being incorporated into this proxy statement/prospectus. The information about how you can obtain certain documents that are incorporated by reference into this proxy statement/prospectus at these websites is being provided only for your convenience.

This document, which forms part of a registration statement on Form S-4 filed with the SEC by Entegris, constitutes a prospectus of Entegris under Section 5 of the Securities Act of 1933, as amended, which is referred to as the Securities Act, with respect to the shares of common stock of Entegris to be issued to CMC stockholders pursuant to the Agreement and Plan of Merger, dated as of December 14, 2021, by and among CMC, Entegris and Yosemite Merger Sub, Inc. as it may be amended from time to time, which is referred to as the merger agreement. This document also constitutes a proxy statement of CMC under Section 14(a) of the Securities Exchange Act of 1934, as amended, which is referred to as the Exchange Act. It also constitutes a notice of meeting with respect to the special meeting.

Entegris has supplied all information contained or incorporated by reference into this proxy statement/prospectus relating to Entegris and Merger Sub, and CMC has supplied all such information relating to CMC. Entegris and CMC have both contributed to the information related to the merger contained in this proxy statement/prospectus.

You should rely only on the information contained in or incorporated by reference into this proxy statement/prospectus. Entegris and CMC have not authorized anyone to provide you with information that is different from that contained in or incorporated by reference into this proxy statement/prospectus. This proxy statement/prospectus is dated January 28, 2022 and you should not assume that the information contained in this proxy statement/prospectus is accurate as of any date other than such date unless otherwise specifically provided herein.

Further, you should not assume that the information incorporated by reference into this proxy statement/prospectus is accurate as of any date other than the date of the incorporated document. Neither the mailing of this proxy statement/prospectus to CMC stockholders nor the issuance by Entegris of shares of its common stock pursuant to the merger agreement will create any implication to the contrary.

This proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.

All references in this proxy statement/prospectus to “Entegris” refer to Entegris, Inc., a Delaware corporation. All references in this proxy statement/prospectus to “CMC” refer to CMC Materials, Inc., a Delaware corporation. All references in this proxy statement/prospectus to the “combined company” refer to Entegris immediately following completion of the merger and the other transactions contemplated by the merger agreement. All references in this proxy statement/prospectus to “Entegris common stock” refer to the common stock of Entegris, par value $0.01 per share, and all references in this proxy statement/prospectus to “CMC common stock” refer to the common stock of CMC, par value $0.001 per share.

The following are some questions that you, as a stockholder of CMC, may have regarding the merger and the other matters being considered at the special meeting of CMC’s stockholders, and brief answers to those questions. You are urged to carefully read this proxy statement/prospectus and the other documents referred to in this proxy statement/prospectus in their entirety because this section may not provide all the information that is important to you regarding these matters. Additional important information is contained in the annexes to, and the documents incorporated by reference into, this proxy statement/prospectus. You may obtain the information incorporated by reference in this proxy statement/prospectus, without charge, by following the instructions under the section entitled “Where You Can Find More Information” beginning on page 169.

In order to complete the merger, among other things, CMC stockholders must adopt the merger agreement in accordance with the Delaware General Corporation Law, which proposal is referred to as the merger agreement proposal.

CMC is holding a special meeting of its stockholders to obtain approval of the merger agreement proposal. CMC stockholders will also be asked to approve, on an advisory (non-binding) basis, the merger-related executive officer compensation payments that will or may be paid by CMC to its named executive officers in connection with the merger, which proposal is referred to as the compensation proposal, and to approve the proposal to adjourn the special meeting to solicit additional proxies if there are not sufficient votes at the time of the special meeting to approve the merger agreement proposal or to ensure that any supplement or amendment to this proxy statement/prospectus is timely provided to CMC stockholders, which proposal is referred to as the adjournment proposal.

Your vote is very important, regardless of the number of shares that you own. The approval of the merger agreement proposal is a condition to the obligations of CMC and Entegris to complete the merger. Neither the approval of the compensation proposal or the adjournment proposal are conditions to the obligations of CMC or Entegris to complete the merger.

Even if you plan to attend the special meeting virtually, CMC recommends that you vote your shares in advance as described below so that your vote will be counted if you later decide not to or become unable to attend the special meeting via the special meeting website. If your shares of CMC common stock are held in street name and you wish to vote your shares at the special meeting via the special meeting website, you must have your specific 16-digit control number, which is included on your proxy card or the voting instruction form from your bank, broker, trustee or other nominee. Please contact your bank, broker, trustee or other nominee to obtain further instructions.

As a CMC stockholder, if you do not return or submit your proxy or vote at the special meeting as provided in this proxy statement/prospectus, the effect will be the same as a vote “AGAINST” the merger agreement proposal, but will have no effect on the compensation proposal or the adjournment proposal. The CMC board of directors unanimously recommends that you vote “FOR” the merger agreement proposal, “FOR” the compensation proposal and “FOR” the adjournment proposal.

If the merger is completed, CMC will no longer be a public company and CMC common stock will be delisted from the NASDAQ, will be deregistered under the Exchange Act and will cease to be publicly traded. Entegris common stock will, after the effective time, constitute shares of the combined company. As referred to in this proxy statement/prospectus, the “effective time” means the date and time when the certificate of merger has been duly filed with and accepted by the Secretary of State of the State of Delaware, or such later date and time as may be agreed by Entegris and CMC in writing and specified in the certificate of merger.

Because each share of CMC common stock will be exchanged for cash and a fixed number of shares of Entegris common stock, the value of the merger consideration that CMC stockholders will receive in the merger will depend on the market price of shares of Entegris common stock at the time the merger is completed. The market price of shares of Entegris common stock that CMC stockholders receive after the merger is completed could be greater than, less than or the same as the market price of shares of Entegris common stock on the date of this proxy statement/prospectus or at the time of the special meeting. Accordingly, you should obtain current market quotations for Entegris common stock and CMC common stock before deciding how to vote with respect to the adoption of the merger agreement. Entegris common stock and CMC common stock are traded on the NASDAQ under the symbols “ENTG” and “CCMP,” respectively.

For more information regarding the merger consideration to be received by CMC stockholders if the merger is completed, see the section entitled “The Merger Agreement—Merger Consideration” beginning on page 70.

stock unit award), and (vii) each contingent right to receive the cash value of a share of CMC common stock held by select employees of CMC who primarily provide services in a jurisdiction other than the United States will vest in full and be cancelled and converted into the right to receive an amount equal to the sum of (x) the cash consideration and (y) the product (rounded to the nearest cent) obtained by multiplying (A) the exchange ratio by (B) the Entegris trading price (as defined below).

As referred to in this proxy statement/prospectus, the equity award exchange ratio refers to the sum of (i) the exchange ratio and (ii) the quotient (rounded to the fourth decimal place) of (x) the cash consideration divided by (y) the volume weighted average price per share of Entegris common stock on the NASDAQ, for the consecutive period of 10 trading days beginning on the 12th trading day immediately preceding the closing date and concluding at the close of trading on the second trading day immediately preceding the closing date. The amount in clause (y) is referred to as the Entegris trading price.

In considering the recommendations of the CMC board of directors, CMC stockholders should be aware that CMC’s directors and executive officers have interests in the merger that are different from, or in addition to, their interests as CMC stockholders. These interests may include, among others, the payment of severance benefits and acceleration of outstanding CMC equity awards upon certain terminations of employment or service, the payment of retention bonuses and Entegris and the surviving company’s agreement to indemnify CMC directors and officers against certain claims and liabilities. For a more complete description of these interests, see the information provided in the section entitled “Interests of CMC’s Directors and Executive Officers in the Merger” beginning on page 112.

Each holder of shares of CMC common stock of record on January 25, 2022 who has not yet received this proxy statement/prospectus will receive this proxy statement/prospectus and have the opportunity to vote on the matters described in this proxy statement/prospectus. Proxies delivered before the record date will be valid and effective so long as the holder providing the proxy is a holder on the record date. If you are not a holder of record on the record date, any proxy you deliver will not be counted. If you deliver a proxy before the record date and remain a holder on the record date, you do not need to deliver another proxy after the record date. If you deliver a proxy before the record date and do not revoke that proxy, your proxy will be deemed to cover the number of shares of CMC common stock you own on the record date even if that number is different from the number of shares of CMC common stock you owned when you executed and delivered your proxy card.

A “broker non-vote” occurs on an item when (a) a bank, broker or other nominee has discretionary authority to vote on one or more proposals to be voted on at a meeting of stockholders, but is not permitted to vote on other proposals without instructions from the beneficial owner of the shares and (b) the beneficial owner fails to provide the bank, broker or other nominee with such instructions. Because none of the proposals currently scheduled to be voted on at the special meeting are routine matters for which brokers may have discretionary authority to vote, CMC does not expect there to be any broker non-votes at the special meeting.

Proposal 2: Compensation proposal. Assuming a quorum is present, approval of the compensation proposal requires the affirmative vote of a majority of the votes cast at the special meeting on this proposal. Accordingly,

a CMC stockholder’s abstention from voting, a broker non-vote or the failure of a CMC stockholder to vote (including the failure of a CMC stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have no effect on the compensation proposal.

Proposal 3: Adjournment proposal. The special meeting may be adjourned to solicit additional proxies if there are not sufficient votes at the time of the special meeting to approve the merger agreement proposal or to ensure that any supplement or amendment to this proxy statement/prospectus is timely provided to CMC stockholders. Whether or not a quorum is present, the affirmative vote of a majority of the votes cast at the special meeting is required to adjourn the special meeting. Accordingly, a CMC stockholder’s abstention from voting, a broker non-vote or the failure of a CMC stockholder to vote (including the failure of a CMC stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have no effect on the adjournment proposal.

Shares in “street name.” If your shares of CMC common stock are held in street name and you wish to vote your shares at the special meeting via the special meeting website, you must have your specific 16-digit control number, which is included on your proxy card or the voting instruction form from your bank, broker, trustee or other nominee. Please contact your bank, broker, trustee or other nominee to obtain further instructions.

Even if you plan to attend the special meeting virtually via the special meeting website, CMC recommends that you vote your shares in advance as described below so that your vote will be counted if you later decide not to or become unable to attend the special meeting via the special meeting website.

Additional information on attending the special meeting can be found under the section entitled “The Special Meeting” on page 40.

Additional information on voting procedures can be found under the section entitled “The Special Meeting” on page 40.

If your shares of common stock in CMC are held by a bank, broker or other nominee, you are considered the beneficial owner of shares held in “street name,” and your bank, broker or other nominee is considered the stockholder of record with respect to those shares. Your bank, broker or other nominee will send you, as the beneficial owner, a package describing the procedure for voting your shares. You should follow the instructions provided by them to vote your shares. You are invited to attend the special meeting virtually via the special meeting website; however, you may not vote these shares at the special meeting unless you obtain a signed legal proxy, executed in your favor, from your bank, broker or other nominee that holds your shares, giving you the right to vote the shares at the special meeting.

For CMC stockholders, the effect of not instructing your bank, broker or other nominee how you wish to vote your shares will be the same as a vote “AGAINST” the merger agreement proposal, and will have no effect on, the compensation proposal (assuming a quorum is present) or the adjournment proposal.

Record Holders. For shares held directly, please complete, sign, date and return each proxy card (or cast your vote by telephone or the Internet as provided on each proxy card) or otherwise follow the voting instructions provided in this proxy statement/prospectus to ensure that all of your shares of CMC common stock are voted.

Shares in “street name.” For shares held in “street name” through a bank, broker or other nominee, you should follow the procedures provided by your bank, broker or other nominee to vote your shares.

Execution or revocation of a proxy will not in any way affect your right to attend the special meeting via the special meeting website. Written notices of revocation and other communications with respect to the revocation of proxies should be addressed to CMC by writing to: 870 North Commons Drive, Aurora, Illinois 60504, Attention: Corporate Secretary.

For more information, see the section entitled “The Special Meeting—Revocability of Proxies” beginning on page 42, as applicable.

For further information, see the section entitled “U.S. Federal Income Tax Consequences of the Merger” beginning on page 119.

chief executive officer, chief financial officer or general counsel of the other party certifying that the conditions described in clauses (x) and (y) of this section have been satisfied. No assurance can be given that the required stockholder, governmental and regulatory consents and approvals will be obtained or that the required conditions to closing will be satisfied, and, even if all required consents and approvals are obtained and the conditions are satisfied, no assurance can be given as to the terms, conditions and timing of such consents and approvals. Any delay in completing the merger could cause Entegris not to realize, or to be delayed in realizing, some or all the benefits that Entegris and CMC expect to achieve if the merger is successfully completed within its expected time frame. For a more complete summary of the conditions that must be satisfied or waived before completion of the merger, see the section entitled “The Merger Agreement—Conditions to the Completion of the Merger” beginning on page 92.

Innisfree M&A Incorporated

501 Madison Avenue, 20th Floor

New York, New York 10022

Toll-Free: (877) 750-8334

Call Collect: (212) 750-5833

If your shares are held for you by a bank, broker, trust or other nominee, you should also call your bank, broker, trust or other nominee for additional information.

The following table shows a summary of the unaudited pro forma condensed combined financial information about the financial condition and results of operations of the combined company, after giving effect to the merger and related debt financing transactions, which were prepared using the acquisition method of accounting with Entegris as the accounting acquirer of CMC. See the section entitled “The Merger—Accounting Treatment” beginning on page 67.

Entegris’ fiscal year ends on December 31, whereas CMC’s fiscal year ends on September 30. Due to this difference in year end, for the purpose of the unaudited pro forma condensed combined statement of operations for the twelve months ended December 31, 2020, the CMC financial results for the twelve months ended December 31, 2020, have been calculated by adding its financial results for the three months ended December 31, 2020 to its financial results for the twelve months ended September 30, 2020 and subtracting its financial results for the three months ended December 31, 2019. The unaudited pro forma condensed combined statement of operations, which is referred to as the pro forma statement of operations, for the twelve months ended December 31, 2020 combines the Entegris audited consolidated statement of operations for the year ended December 31, 2020 and the CMC financial results for the twelve months ended December 31, 2020. This gives effect to the merger as if it had been consummated on January 1, 2020. For the purpose of the unaudited pro forma condensed combined statements of operations for the nine months ended October 2, 2021, the CMC financial results for the nine months ended September 30, 2021 have been calculated by subtracting its financial results for the three months ended December 31, 2020 from its financial results for the twelve months ended September 30, 2021. The unaudited pro forma condensed combined statement of operations, which we refer to as the pro forma statement of operations, for the nine months ended October 2, 2021 combines the Entegris unaudited consolidated statement of operations for the nine-month period ended October 2, 2021, and the CMC financial results for the nine months ended September 30, 2021. This gives effect to the merger as if it had been consummated on January 1, 2020.

We refer to the unaudited pro forma condensed combined balance sheet and the unaudited pro forma condensed combined statements of operations as the pro forma financial statements.

The pro forma financial statements have been developed from and should be read in conjunction with the section entitled “Unaudited Pro Forma Condensed Combined Financial Statements” and the notes related thereto beginning on page 96 and with the historical consolidated financial statements of Entegris and CMC and related notes that have been filed with the SEC, certain of which are incorporated by reference into this proxy statement.

The pro forma financial statements have been prepared by management in accordance with SEC Regulation S-X Article 11, Pro Forma Financial Information for illustrative and informational purposes only. The pro forma financial statements are not necessarily indicative of what the combined company’s balance sheet or statement of operations actually would have been had the merger been completed as of the dates indicated. In addition, the pro forma financial statements do not purport to project the future financial position or operating results of the combined company. As a result of displaying amounts in thousands, rounding differences may exist in the tables in this section. Future results may vary significantly from the results reflected because of various factors, including those discussed in the section entitled “Risk Factors” beginning on page 27.

The pro forma financial statements have been prepared using the acquisition method of accounting under GAAP with Entegris being the accounting acquirer in the proposed merger of Entegris and CMC. See the section entitled “The Merger—Accounting Treatment” beginning on page 67. The transaction accounting adjustments are preliminary, based upon available information and made solely for the purpose of providing these pro forma financial statements. Differences between these preliminary estimates and the final acquisition accounting will occur and these differences could have a material impact on the accompanying pro forma financial statements and the future results of operations and financial position of the combined company.

The following table sets forth selected per share information for Entegris common stock on a historical basis for the year ended December 31, 2020 and nine-months ended October 2, 2021, selected per share information for CMC common stock on a historical basis for the twelve month period ended December 31, 2020 and nine-months ended October 2, 2021, selected per share information for the combined company’s common stock on a pro forma combined basis for the year ended December 31, 2020 and nine-months ended October 2, 2021 and selected per share information for CMC common stock on a pro forma equivalent basis for the 12 month period ended December 31, 2020 and nine-month period ended October 2, 2021. The per share information reflects the Entegris common stock and CMC common stock issued and outstanding (excluding any shares that are held in treasury).

The combined company’s pro forma combined earnings per share was calculated in the section entitled “Notes to the Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page 96.

The following table sets forth, for the calendar periods indicated, the high and low sales prices per share of Entegris common stock and per share of CMC common stock as reported on the NASDAQ, respectively, as well as the dividends declared with respect to shares of Entegris stock and CMC stock. The shares of Entegris common stock are traded on the NASDAQ under the symbol “ENTG,” and the shares of CMC common stock are traded on the NASDAQ under the symbol “CCMP.”

The following table sets forth the closing sale price per share of Entegris common stock and per share of CMC common stock as reported on the NASDAQ, respectively, on December 14, 2021, the last trading day before the public announcement of the merger agreement, and on January 25, 2022, the latest practicable date before the date of this proxy statement/prospectus. The table also shows the implied value of the merger consideration as of the same two dates. This implied value was calculated by multiplying the closing sale price of a share of Entegris common stock as of the specified date by the exchange ratio of 0.4506 and adding $133.00, the cash component of the merger consideration.

The market prices of shares of Entegris common stock and CMC common stock have fluctuated since the date of the announcement of the merger agreement and will continue to fluctuate from the date of this proxy statement/prospectus to the dates of the special meeting and the closing date. No assurance can be given concerning the market prices of shares of Entegris common stock or CMC common stock before completion of the merger or shares of Entegris common stock after completion of the merger. The exchange ratio is fixed in the merger agreement, but the market price of shares of Entegris common stock (and therefore the value of the merger consideration when received by CMC stockholders upon completion of the merger) could be greater than, less than or the same as shown in the table above. Accordingly, CMC stockholders are advised to obtain current market quotations for shares of Entegris common stock and CMC common stock in connection with deciding how to vote on the proposal to adopt the merger agreement.

Entegris currently pays a quarterly dividend on shares of Entegris common stock and last declared a dividend of $0.08 per share on October 13, 2021, that was paid on November 17, 2021, to stockholders of record as of October 27, 2021. Under the terms of the merger agreement, Entegris is not permitted to establish a record date for, declare, set aside for payment or pay any dividend between signing and closing without CMC’s consent other than regular quarterly cash dividends in the ordinary course of business.

CMC currently pays a quarterly dividend on shares of CMC common stock and last declared a dividend of $0.46 per share on December 7, 2021, which will be paid on or about January 28, 2022, to stockholders of record as of December 22, 2021. Under the terms of the merger agreement, other than the payment of the dividend declared by CMC on December 7, 2021, CMC is not permitted to establish a record date for, declare, set aside for payment or pay any dividend between signing and closing without Entegris’ consent, except that CMC may declare and pay a quarterly dividend of $0.46 per share in March 2022 and, if the closing does not occur by December 14, 2022, CMC may declare and pay quarterly dividends in an amount not to exceed $0.46 per share in a manner consistent with CMC’s past practice.

This registration statement on Form S-4, of which this proxy statement/prospectus forms a part, and the documents to which CMC and Entegris refer you in this registration statement, as well as oral statements made or to be made by Entegris and CMC, include certain “forward-looking statements” within the meaning of, and subject to the safe harbor created by, Section 27A of the Securities Act, Section 21E of the Exchange Act and the Private Securities Litigation Reform Act of 1995, which are referred to as the safe harbor provisions. Statements included in or incorporated by reference into this registration statement, of which this proxy statement/prospectus forms a part, that are not historical facts are forward-looking statements, including statements about the beliefs and expectations of the management of each of Entegris and CMC. Words such as “believe,” “continue,” “could,” “expect,” “anticipate,” “intends,” “estimate,” “forecast,” “project,” “should,” “may,” “will,” “would” or the negative thereof and similar expressions are intended to identify such forward-looking statements that are intended to be covered by the safe harbor provisions. Entegris and CMC caution investors that any forward-looking statements, including statements related to anticipated results of operations, business strategies of Entegris, CMC and the combined company, anticipated benefits of the proposed transaction, the anticipated impact of the proposed transaction on Entegris’ and CMC’s business and future financial and operating results, the expected amount and timing of synergies from the proposed transaction, the anticipated closing date for the proposed transaction and other aspects of CMC’s and Entegris’ operations or operating results, are only predictions and involve known and unknown risks and uncertainties, many of which are beyond Entegris’ and CMC’s control, and could cause actual results to differ materially from those indicated in such forward-looking statements, which speak only as of the date of this proxy statement/prospectus. These factors and risks include, but are not limited to, (i) weakening of global and/or regional economic conditions, generally or specifically in the semiconductor industry, which could decrease the demand for Entegris’ and CMC’s products and solutions; (ii) the parties’ ability to meet rapid demand shifts; (iii) the parties’ ability to continue technological innovation and introduce new products to meet customers’ rapidly changing requirements; (iv) Entegris’ and CMC’s ability to protect and enforce intellectual property rights; (v) operational, political and legal risks of Entegris’ and CMC’s international operations; (vi) the increasing complexity of certain manufacturing processes; (vii) raw material shortages, supply and labor constraints and price increases; (viii) changes in government regulations of the countries in which Entegris and CMC operate; (ix) the fluctuation of currency exchange rates; (x) fluctuations in the market price of Entegris’ stock; (xi) the level of, and obligations associated with, Entegris’ and CMC’s indebtedness; (xii) the impact of public health crises, such as pandemics (including coronavirus (COVID-19)) and epidemics and any related company or government policies and actions to protect the health and safety of individuals or government policies or actions to maintain the functioning of national or global economies and markets; and (xiii) other risk factors and additional information. In addition, risks that could cause actual results to differ from forward-looking statements include: the inherent uncertainty associated with financial or other projections; the prompt and effective integration of CMC’s businesses and the ability to achieve the anticipated synergies and value-creation contemplated by the proposed transaction; the risk associated with CMC’s ability to obtain the approval of the proposed transaction by its stockholders required to consummate the proposed transaction and the timing of the closing of the proposed transaction, including the risk that the conditions to the transaction are not satisfied on a timely basis or at all and the failure of the transaction to close for any other reason; the risk that a regulatory consent or authorization that may be required for the proposed transaction is not obtained or is obtained subject to conditions that are not anticipated; unanticipated difficulties or expenditures relating to the transaction, the outcome of any legal proceedings related to the merger, the response and retention of business partners and employees as a result of the announcement and pendency of the transaction; and the diversion of management time on transaction-related issues. Investors are cautioned not to place undue reliance on these forward-looking statements.

All subsequent written or oral forward-looking statements attributable to Entegris or CMC or any person acting on its or their behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. Neither CMC nor Entegris is under any obligation, and each expressly disclaims any obligation, to update, alter, or otherwise revise any forward-looking statements, whether written or oral, that may be made from time to time, whether as a result of new information, future events or otherwise, except as may be required by law.

In deciding whether to vote for the adoption of the merger agreement, CMC stockholders are urged to carefully consider all the information included or incorporated by reference in this proxy statement/prospectus, which is listed in the section entitled “Where You Can Find More Information” beginning on page 169. CMC stockholders should also read and consider the risks associated with each of the businesses of Entegris and CMC because these risks will also affect the combined company. The risks associated with the business of Entegris can be found in Entegris’ Annual Report on Form 10-K for the fiscal year ended December 31, 2020 and the risks associated with the business of CMC can be found in CMC’s Annual Report on Form 10-K for the year ended September 30, 2021, as such risks may be updated or supplemented in each company’s subsequently filed Quarterly Reports on Form 10-Q or Current Reports on Form 8-K (excluding any information and exhibits furnished under Item 2.02 or 7.01 thereof), each of which are incorporated by reference into this proxy statement/prospectus. In addition, CMC stockholders are urged to carefully consider the following material risks relating to the merger, the business of Entegris, the business of CMC and the business of the combined company. Entegris stockholders will not vote on the merger.

Upon completion of the merger, each share of CMC common stock outstanding immediately before the merger will be converted into and become exchangeable for $133 in cash and 0.4506 shares of Entegris common stock. This exchange ratio is fixed in the merger agreement and will not be adjusted for changes in the market price of either Entegris common stock or CMC common stock. The market prices of Entegris common stock and CMC common stock have fluctuated before and after the date of the announcement of the merger agreement and will continue to fluctuate from the date of this proxy statement/prospectus to the date of the special meeting, respectively, and the date the merger is consummated, and the market price of the common stock of Entegris will continue to fluctuate thereafter.

Because part of the value of the merger consideration will depend on the market price of Entegris common stock at the time the merger is completed, CMC stockholders will not know or be able to determine at the time of the special meeting the market value of the merger consideration they would receive upon completion of the merger.

Stock price changes may result from a variety of factors, including, among others, general market and economic conditions, changes in Entegris’ or CMC’s respective businesses, operations and prospects, reductions or changes in U.S. and foreign government spending or budgetary policies, market assessments of the likelihood that the merger will be completed, interest rates, general market, industry and economic conditions and other factors generally affecting the respective prices of Entegris’ or CMC’s common stock, federal, state and local legislation, governmental regulation and legal developments in the industry segments in which CMC or Entegris operate, and the timing of the merger and receipt of required regulatory approvals.

Many of these factors are beyond Entegris’ and CMC’s control, and neither Entegris nor CMC are permitted to terminate the merger agreement solely due to a decline in the market price of the common stock of the other party. You are urged to obtain current market quotations for Entegris common stock and CMC common stock in determining whether to vote for the adoption of the merger agreement. In addition, see the section entitled “Comparative Per Share Market Price Data and Dividend Information” beginning on page 24.

The merger is subject to a number of conditions that must be satisfied, including the approval by CMC stockholders of the merger agreement proposal, or waived (to the extent permissible), in each case before the completion of the merger. These conditions are described in the section entitled “The Merger Agreement—Conditions to the Completion of the Merger” beginning on page 92. These conditions to the completion of the merger, some of which are beyond the control of Entegris and CMC, may not be satisfied or waived in a timely manner or at all, and, accordingly, the merger may be delayed or not completed.

Additionally, either Entegris or CMC may terminate the merger agreement under certain circumstances, including, among other reasons, if the merger is not completed by December 14, 2022 (which date may be extended to March 14, 2023, under certain circumstances). In addition, if the merger agreement is terminated under certain circumstances specified in the merger agreement, CMC may be required to pay Entegris a termination fee of

$187 million, including certain circumstances in which the CMC board of directors effects an adverse recommendation change (as defined in the section entitled “The Merger Agreement—No Change of Recommendation—Permitted Change of Recommendation” beginning on page 83) or CMC enters into an agreement with respect to a superior proposal following the termination of the merger agreement. See the section entitled “The Merger Agreement—Termination of the Merger Agreement” beginning on page 93 and the section entitled “The Merger Agreement—Termination Fees” beginning on page 94 for a more complete discussion of the circumstances under which the merger agreement could be terminated and when a termination fee may be payable by CMC.

Whether or not the merger is completed, the announcement and pendency of the merger could cause disruptions in the businesses of Entegris and CMC. If the merger is not completed for any reason, including as a result of a failure to obtain the required CMC vote or the failure to obtain the requisite regulatory approvals, the ongoing businesses of Entegris and CMC may be adversely affected. Entegris and CMC may be subject to a number of risks, including the following:

Upon consummation of the merger, Entegris stockholders and CMC stockholders will both hold shares of common stock in Entegris. Entegris’ businesses differ from those of CMC, and CMC’s businesses differ from those of Entegris, and, accordingly, the results of operations of Entegris following the merger will be affected by some factors that are different from those currently or historically affecting the results of operations of Entegris and those currently or historically affecting the results of operations of CMC. The results of operations of Entegris following the merger may also be affected by factors different from those that currently affect or have historically affected either Entegris or CMC. For a discussion of the businesses of each of Entegris and CMC and some important factors to consider in connection with those businesses, see the section entitled “The Parties to the Merger” beginning on page 39 and the documents and information included elsewhere in this proxy statement/prospectus or incorporated by reference into this proxy statement/prospectus and listed under the section entitled “Where You Can Find More Information” beginning on page 169.

Upon consummation of the merger, the rights of CMC stockholders, who will become stockholders of Entegris following the merger, will be governed by the certificate of incorporation and bylaws of Entegris. The rights associated with CMC common stock are different from the rights that will be associated with the common stock of Entegris. See the section entitled “Comparison of Stockholders’ Rights” beginning on page 122 for a discussion of these rights.

From and after the date of the merger agreement and before completion of the merger, the merger agreement restricts Entegris and CMC from taking specified actions without the consent of the other party (with CMC being restricted from taking a broader set of specified actions than Entegris) and requires that the business of each company and its respective subsidiaries be conducted in all material respects in the ordinary course of business consistent with past practice. These restrictions may prevent Entegris or CMC from making appropriate changes to their respective businesses or organizational structures or from pursuing attractive business opportunities that may arise before the completion of the merger, and could have the effect of delaying or preventing other strategic transactions. Adverse effects arising from the pendency of the merger could be exacerbated by any delays in consummation of the merger or termination of the merger agreement. See the section entitled “The Merger Agreement—Conduct of Business Before the Effective Time” beginning on page 76.

The merger is subject to a number of conditions to closing as specified in the merger agreement. These closing conditions include, among others, approval for listing on the NASDAQ of the shares of Entegris common stock to be issued pursuant to the merger agreement, the expiration or earlier termination of any applicable waiting period, and the receipt of approvals under, U.S. and foreign antitrust and competition laws in China, Japan, Singapore, South Korea, and Taiwan, the absence of governmental restraints or prohibitions preventing the consummation of the merger in certain jurisdictions, the effectiveness of the registration statement on Form S-4 registering the Entegris common stock issuable pursuant to the merger agreement and the absence of any stop order or proceedings by the SEC with respect thereto. The obligation of each of CMC and Entegris to consummate the merger is also conditioned on, among other things, the absence of a material adverse effect on the other party, the truth and correctness of the representations and warranties made by the other party on the date of the merger agreement and on the closing date (subject to certain materiality qualifiers), and the performance by the other party in all material respects of its obligations under the merger agreement. No assurance can be given that the required stockholder, governmental and regulatory consents and approvals will be obtained or that the required conditions to closing will be satisfied, and, if all required consents and approvals are obtained and the conditions are satisfied, no assurance can be given as to the terms, conditions and timing of such consents and approvals. Any delay in completing the merger could cause Entegris not to realize, or to be delayed in realizing, some or all the benefits that Entegris and CMC expect to achieve if the merger is successfully completed within its expected time frame. For a more complete summary of the conditions that must be satisfied or waived before completion of the merger, see the section entitled “The Merger Agreement—Conditions to the Completion of the Merger” beginning on page 92.

The completion of the merger is subject to the receipt of antitrust clearance in the United States and in China, Japan, Singapore, South Korea, and Taiwan.

With respect to the United States, under the HSR Act, the merger may not be completed until notification and report forms have been filed with the FTC and the DOJ and the applicable waiting period has expired or been terminated. A transaction requiring notification under the HSR Act may not be completed until the expiration of a 30-calendar-day waiting period following the parties’ filing of their respective HSR notifications or the early

termination of that waiting period. If the FTC or DOJ issues a Second Request before the expiration of the initial waiting period, the parties must observe a second 30-day waiting period, which would begin to run only after both parties have substantially complied with the Second Request, unless the waiting period is terminated earlier or the parties otherwise agree to extend the waiting period. Entegris and CMC each filed an HSR notification with the FTC and the DOJ on December 29, 2021 and the initial waiting period is scheduled to expire at 11:59 p.m., Eastern Time, on January 28, 2022.

At any time before or after consummation of the merger, notwithstanding the expiration or termination of the applicable waiting period under the HSR Act, the DOJ or the FTC, or any state, could take such action under the antitrust laws as it deems necessary or desirable in the public interest, including seeking to enjoin the completion of the merger, seeking divestiture of substantial assets of the parties or requiring the parties to license, or hold separate, assets or terminate existing relationships and contractual rights. Private parties may also seek to take legal action under the antitrust laws under certain circumstances.

The merger is also subject to clearance or approval by antitrust authorities in certain other jurisdictions. With respect to China and Japan, Entegris and CMC jointly submitted the initial notifications with SAMR and the JFTC, respectively, on January 7, 2022. With respect to Singapore, South Korea and Taiwan, Entegris and CMC submitted the initial notifications to the CCCS, the KFTC and the TFTC, respectively, on January 10, 2022. The approvals are currently pending in these applicable jurisdictions. The merger cannot be completed until Entegris and CMC obtain approval to consummate the merger or applicable waiting periods have expired or been terminated in each applicable jurisdiction. Entegris and CMC, in consultation and cooperation with each other, will file notifications, as required with antitrust authorities in certain other jurisdictions, as promptly as practicable after the date of the merger agreement. The relevant antitrust authorities could take such actions under the applicable antitrust laws as they deem necessary or desirable, including seeking divestiture of substantial assets of the parties or requiring the parties to license, or hold separate, assets or terminate existing relationships and contractual rights. For a more complete summary of the efforts Entegris and CMC must make to obtain regulatory approvals, see the section entitled “The Merger Agreement—Regulatory Approvals” beginning on page 66. There is no assurance that Entegris and CMC will obtain all required antitrust clearances or approvals on a timely basis, if at all. Each of Entegris and CMC is required under the merger agreement to defend or contest any action asserted in any court, agency or other proceeding by any person or entity (including any governmental antitrust entity) seeking to delay, restrain, prevent, enjoin or otherwise prohibit consummation of the merger. In addition, each of Entegris and CMC is required under the merger agreement to take, effect or agree to any regulatory action (as defined in the section entitled “The Merger Agreement—Reasonable Best Efforts” beginning on page 84) if such regulatory action is required to obtain regulatory clearance or approval or expiration or termination of the applicable waiting periods, although no such regulatory action is required if it is not conditioned upon the closing of the merger or if such regulatory action, individually or in the aggregate with any other regulatory action, would reasonably be expected to have a material adverse effect on Entegris and its subsidiaries (including the surviving corporation and its subsidiaries), taken as a whole after giving effect to the merger, but measured on a scale relative to the size of CMC and its subsidiaries, taken as a whole, before the merger. For a description of the parties’ obligations with respect to regulatory approvals related to the merger, see the section entitled “The Merger Agreement—Reasonable Best Efforts” beginning on page 84.

Failure to obtain the necessary clearance in any of these jurisdictions could substantially delay or prevent the consummation of the merger in certain jurisdictions, which could negatively impact both Entegris and CMC.

The success of the merger will depend in part on the retention of personnel critical to the business and operations of Entegris following the merger due to, for example, their technical skills or management expertise. Competition for qualified personnel can be intense.

Current and prospective employees of Entegris and CMC may experience uncertainty about their future role with Entegris and CMC until strategies with regard to these employees are announced or executed, which may impair Entegris’ and CMC’s ability to attract, retain and motivate key management, sales, marketing, technical and other personnel before and following the merger. Employee retention may be particularly challenging during the pendency of the merger, as employees of Entegris and CMC may experience uncertainty about their future roles with Entegris following the merger. If Entegris and CMC are unable to retain personnel, including Entegris’ and CMC’s key management, who are critical to the successful integration and future operations of the companies, Entegris and CMC could face disruptions in their operations, loss of existing customers or loss of sales to existing customers, loss of key

information, expertise or know-how, and unanticipated additional recruitment and training costs. In addition, the loss of key personnel could diminish the anticipated benefits of the merger.

If key employees of Entegris or CMC depart, the integration of the companies may be more difficult and Entegris’ business following the merger may be harmed. Furthermore, Entegris may have to incur significant costs in identifying, hiring and retaining replacements for departing employees and may lose significant expertise and talent relating to the business of each of Entegris or CMC, and Entegris’ ability to realize the anticipated benefits of the merger may be adversely affected. In addition, there could be disruptions to or distractions for the workforce and management associated with activities of labor unions or integrating employees into Entegris. No assurance can be given that Entegris will be able to attract or retain key employees of Entegris and CMC to the same extent that those companies have been able to attract or retain their own employees in the past.

The merger will happen only if the stated conditions are met, including the adoption of the merger agreement by CMC stockholders and the receipt of the requisite regulatory approvals, among other conditions. Many of the conditions are outside the control of Entegris and CMC, and both parties also have certain rights to terminate the merger agreement. Accordingly, there may be uncertainty regarding the completion of the merger. This uncertainty may cause customers, suppliers, vendors, strategic partners or others that deal with Entegris or CMC to delay or defer entering into contracts with Entegris or CMC or making other decisions concerning Entegris or CMC or seek to change or cancel existing business relationships with Entegris or CMC, which could negatively affect their respective businesses. Any delay or deferral of those decisions or changes in existing agreements could have an adverse impact on the respective businesses of Entegris and CMC, regardless of whether the merger is ultimately completed.

In addition, the merger agreement restricts Entegris, CMC and their respective subsidiaries from making certain acquisitions and taking other specified actions until the merger occurs without the consent of the other parties. These restrictions may prevent Entegris and CMC from pursuing attractive business opportunities or strategic transactions that may arise before the completion of the merger. See the section entitled “The Merger Agreement—Conduct of Business Before the Effective Time” beginning on page 76 for a description of the restrictive covenants to which each of Entegris and CMC is subject.

Goldman Sachs rendered an oral opinion to the CMC board of directors on December 14, 2021, subsequently confirmed in writing by delivery of Goldman Sachs’ opinion dated as of December 15, 2021, to the effect that, as of such date, and based upon and subject to the assumptions, procedures, factors, qualifications and limitations set forth in its written opinion, the merger consideration to be paid to the holders of CMC common stock in the merger was fair, from a financial point of view, to such holders.

CMC has not obtained, nor will it obtain, an updated opinion regarding the fairness, from a financial point of view, of the merger consideration as of the date of this proxy statement/prospectus or before the completion of the merger from Goldman Sachs. Goldman Sachs’ opinion was necessarily based on economic, monetary, market and other conditions as in effect on, and the information made available to Goldman Sachs, as applicable, only as of the date of the opinion of Goldman Sachs and does not address the fairness of the merger consideration, from a financial point of view, at the time the merger is completed. Changes in the operations and prospects of Entegris or CMC, general economic, monetary, market and other conditions and other factors that may be beyond the control of Entegris and CMC, and, in the case of CMC, on which the opinion of Goldman Sachs was based, may alter the value of Entegris or CMC or the prices of shares of Entegris common stock or CMC common stock by the time the merger is completed. The opinion of Goldman Sachs does not speak as of any date other than the respective dates of such opinions. The recommendation of the CMC board of directors that CMC stockholders vote “FOR” the merger agreement proposal, “FOR” the compensation proposal and “FOR” the adjournment proposal are each made as of the date of this proxy statement/prospectus. For a description of the opinion that CMC received from Goldman Sachs, its financial advisor, see the section entitled “The Merger—Opinion of CMC’s Financial Advisor” beginning on page 57.

When considering the recommendations of the CMC board of directors with respect to the proposals described in this proxy statement/prospectus, CMC stockholders should be aware that the directors and executive officers of CMC have interests in the merger that are different from, or in addition to, those of CMC stockholders generally. These interests include the potential for continued employment of certain executive officers of CMC by Entegris, the treatment in the merger of outstanding equity, equity-based and incentive awards, severance arrangements, other compensation and benefit arrangements, and the right to continued indemnification of former CMC directors and officers by Entegris and the surviving company.

CMC stockholders should be aware of these interests when they consider the recommendations of the CMC board of directors that they vote to adopt the merger agreement. The CMC board of directors was aware of these interests when it approved and declared advisable the merger agreement, the merger and the transactions contemplated thereby on the terms and subject to the conditions set forth in the merger agreement, determined that the merger agreement, the merger and the transactions contemplated by the merger agreement were advisable, fair to and in the best interests of, CMC and CMC stockholders and recommended that CMC stockholders adopt the merger agreement. The interests of CMC directors and executive officers are described in more detail in the section entitled “Interests of CMC’s Directors and Executive Officers in the Merger” beginning on page 112.

Entegris or CMC may determine to waive, in whole or part, one or more of the conditions of its obligations to consummate the merger. Entegris and CMC currently expect to evaluate the materiality of any waiver and, in the case of CMC, its effect on CMC stockholders, in light of the facts and circumstances at the time to determine whether any amendment of this proxy statement/prospectus or any re-solicitation of proxies or voting cards is required in light of such waiver. Any determination whether to waive any condition to the merger or as to re-soliciting stockholder approval or amending this proxy statement/prospectus as a result of a waiver will be made by Entegris or CMC, as applicable, at the time of such waiver based on the facts and circumstances as they exist at that time.

The merger agreement contains “no shop” provisions that restrict CMC’s ability to, among other things (each as described under the section entitled “The Merger Agreement—No Solicitation of Acquisition Proposals” beginning on page 80):

Furthermore, there are only limited exceptions to the requirement under the merger agreement that the CMC board of directors may not adversely withhold, withdraw, qualify or modify the CMC recommendation, as applicable (as defined in the section entitled “The Merger Agreement—Representations and Warranties” beginning on page 74). Although the CMC board of directors is permitted to effect an adverse recommendation change, after complying with certain procedures set forth in the merger agreement, in response to a superior proposal or an intervening event, if it determines in good faith that a failure to do so would be inconsistent with its fiduciary duties, such an adverse recommendation change would in certain circumstances entitle Entegris to collect a termination fee from CMC in the amount of $187 million. For more information, see the sections entitled “The Merger Agreement—Termination of the Merger Agreement” beginning on page 93 and “The Merger Agreement— Termination Fees” beginning on page 94.

These provisions could discourage a potential competing acquirer from considering or proposing an acquisition or merger, even if it were prepared to pay consideration with a higher value than that implied by the merger consideration, or might result in a potential competing acquirer proposing to pay a lower per share price than it might otherwise have proposed to pay because of the added expense of the termination fee.

Entegris and CMC have incurred and expect to incur a number of non-recurring costs associated with combining the operations of the two companies, as well as transaction fees and other costs related to the merger. These costs and expenses include fees paid to financial, legal and accounting advisors, facilities and systems consolidation costs, severance and other potential employment-related costs, including retention and severance payments that may be made to certain Entegris employees and CMC employees, filing fees, printing expenses and other related charges. Some of these costs are payable by Entegris or CMC regardless of whether the merger is completed.

The combined company will also incur integration costs in connection with the merger. There are a large number of processes, policies, procedures, operations, technologies and systems that must be integrated in connection with the merger and the integration of the two companies’ businesses. Although Entegris and CMC expect that the elimination of duplicative costs, strategic benefits, additional income as well as the realization of other efficiencies related to the integration of the businesses may offset incremental transaction, merger-related and integration costs over time, any net benefit may not be achieved in the near term or at all. Many of these costs will be borne by Entegris or CMC even if the merger is not completed. While both Entegris and CMC have assumed that certain expenses would be incurred in connection with the merger and the other transactions contemplated by the merger agreement, there are many factors beyond their control that could affect the total amount or the timing of the integration and implementation expenses.

Litigation relating to the merger has been filed against CMC and the CMC board of directors, and it is possible that additional litigation by stockholders of Entegris or CMC may be filed against Entegris and the Entegris board of directors and/or CMC and the CMC board of directors in the future. Among other remedies, these claimants could seek damages and/or to enjoin the merger or the other transactions contemplated by the merger agreement. The outcome of any litigation is uncertain and any such lawsuits could prevent or delay the completion of the merger and result in substantial costs to Entegris, CMC and the combined company. Any such actions may create uncertainty relating to the merger and may be costly and distracting to management. Further, the defense or settlement of any lawsuit or claim that remains unresolved at the time the merger is completed may adversely affect the combined company’s business, financial condition and results of operations. For more information, see the section entitled “The Merger—Litigation Related to the Merger beginning on page 68.”

Upon completion of the merger, holders of CMC common stock will receive cash and Entegris common stock and become holders of Entegris common stock. The market price of Entegris common stock may fluctuate significantly following completion of the merger and holders of CMC common stock could lose the value of their investment in Entegris common stock. In addition, any significant price and volume fluctuations of the stock markets could have a material adverse effect on the market for, or liquidity of, the Entegris common stock, regardless of Entegris' actual operating performance. In addition, Entegris' business differs in important respects from that of CMC, and accordingly, the results of operations of the combined company and the market price of Entegris common stock after the completion of the merger may be affected by factors different from those currently affecting the independent results of operations of each of Entegris and CMC. For a discussion of the businesses of Entegris and CMC and of some important factors to consider in connection with those businesses, see the documents incorporated by reference into this proxy statement/prospectus and referred to under “Where You Can Find More Information” beginning on page 169.

As a result of the merger, Entegris may experience impacts on relationships with customers and suppliers that may harm Entegris’ business and results of operations. Certain customers or suppliers may seek to terminate or modify contractual obligations following the merger whether or not contractual rights are triggered as a result of the merger. There can be no guarantee that customers and suppliers will remain with or continue to have a relationship with Entegris or do so on the same or similar contractual terms following the merger. If any customers or suppliers seek to terminate or modify contractual obligations or discontinue the relationship with Entegris, then Entegris’ business and results of operations may be harmed. If certain of Entegris’ suppliers were to seek to terminate or modify an arrangement with Entegris, then Entegris may be unable to procure necessary supplies from other suppliers in a timely and efficient manner and on acceptable terms, or at all.

Entegris and CMC also have contracts with vendors, landlords, licensors and other business partners that may require Entegris or CMC, as applicable, to obtain consent from these other parties in connection with the merger. If these consents cannot be obtained, Entegris may suffer a loss of potential future revenue, incur costs, and lose rights that may be material to its business. In addition, third parties with whom Entegris or CMC currently have relationships may terminate or otherwise reduce the scope of their relationship with either party in anticipation of the merger. Any such disruptions could limit Entegris’ ability to achieve the anticipated benefits of the merger. The adverse effect of any such disruptions could also be exacerbated by a delay in the completion of the merger or by a termination of the merger agreement.

Entegris may be exposed to increased litigation from stockholders, customers, suppliers, consumers and other third parties due to the combination of Entegris’ business and CMC’s business following the merger. Such litigation may have an adverse impact on Entegris’ business and results of operations or may cause disruptions to Entegris’ operations.

The success of the merger will depend on, among other things, the ability of Entegris and CMC to combine their businesses in a manner that facilitates growth opportunities and realizes cost savings. Entegris and CMC have entered into the merger agreement because each believes that the merger and the other transactions contemplated by the merger agreement are fair to and in the best interests of its respective stockholders and that combining the businesses of Entegris and CMC will produce benefits and cost savings. See also the section entitled “Recommendation of the CMC Board of Directors; CMC’s Reasons for the Merger” beginning on page 54.

However, Entegris and CMC must successfully combine their respective businesses in a manner that permits these benefits to be realized. In addition, Entegris must achieve the anticipated growth and cost savings without adversely affecting current revenues and investments in future growth. If Entegris is not able to successfully achieve these objectives, the anticipated benefits of the merger may not be realized fully, or at all, or may take longer to realize than expected.

An inability to realize the full extent of the anticipated benefits of the merger and the other transactions contemplated by the merger agreement, as well as any delays encountered in the integration process, could have an adverse effect upon the revenues, level of expenses and operating results of Entegris, which may adversely affect the value of the common stock of Entegris after the completion of the merger.

In addition, the actual integration may result in additional and unforeseen expenses, and the anticipated benefits of the integration plan may not be realized. Actual growth and cost savings, if achieved, may be lower than what Entegris and CMC expect and may take longer to achieve than anticipated. If Entegris and CMC are not able to adequately address integration challenges, they may be unable to successfully integrate their operations or realize the anticipated benefits of the integration of the two companies.

Entegris and CMC have operated and, until the completion of the merger, will continue to operate independently. There can be no assurances that their businesses can be integrated successfully. It is possible that the integration process could result in the loss of key Entegris employees or key CMC employees, the loss of customers, the disruption of either company’s or both companies’ ongoing businesses, inconsistencies in standards, controls, procedures and policies, unexpected integration issues, higher than expected integration costs and an overall post-completion integration process that takes longer than originally anticipated. Specifically, the following issues, among others, must be addressed in integrating the operations of Entegris and CMC in order to realize the anticipated benefits of the merger so Entegris performs as expected and have an adverse impact on the Entegris common stock:

In addition, at times the attention of certain members of either company’s or both companies’ management and resources may be focused on completion of the merger and the integration of the businesses of the two companies and diverted from day-to-day business operations or other opportunities that may have been beneficial to such company, which may disrupt each company’s ongoing business and the business of Entegris after the merger.

The unaudited pro forma combined financial statements and unaudited pro forma per share data included in this proxy statement/prospectus are presented for illustrative purposes only, contain a variety of adjustments, assumptions and preliminary estimates and are not necessarily indicative of what Entegris’ actual financial position or results of operations would have been had the merger been completed on the dates indicated. Entegris’ actual results and financial position after the merger may differ materially and adversely from the unaudited pro forma financial data included in this proxy statement/prospectus. The unaudited pro forma combined financial information does not reflect the effect of any divestitures that may be required in connection with the merger. For more information, see the sections entitled “Comparative Historical and Unaudited Pro Forma Per Share Data” beginning on page 23 and “Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page 96.

While presented with numeric specificity, the Entegris and CMC unaudited prospective financial information provided in this proxy statement/prospectus is based on numerous variables and assumptions (including, but not limited to, those related to industry performance and competition, general business, the specialty materials and related industries, and economic, market and financial conditions and additional matters specific to Entegris’ or CMC’s business, as applicable) that are inherently subjective and uncertain and are beyond the control of the respective management teams of Entegris and CMC. As a result, actual results may differ materially from the unaudited prospective financial information. Important factors that may affect actual results and cause these unaudited prospective financial information to not be achieved include, but are not limited to, risks and uncertainties relating to Entegris’ or CMC’s business, as applicable (including each company’s ability to achieve strategic goals, objectives and targets over applicable periods), industry performance, general business and economic conditions. For more information see the section entitled “The Merger—Certain Unaudited Prospective Financial Information” beginning on page 63.

The success of the merger will depend in part on Entegris’ ability to retain the talents and dedication of the professionals currently employed by Entegris and CMC. It is possible that these employees may decide not to remain with Entegris or CMC, as applicable, while the merger is pending, or with Entegris after the merger is consummated. If key employees terminate their employment, or if an insufficient number of employees are retained to maintain effective operations, Entegris’ business activities may be adversely affected and management’s attention may be diverted from successfully integrating Entegris and CMC to hiring suitable replacements, all of which may cause Entegris’ business to suffer. In addition, Entegris and CMC may not be able to locate suitable replacements for any key employees that leave either company or offer employment to potential replacements on reasonable terms.

Entegris expects to incur a substantial amount of debt in connection with the merger and has entered into the commitment letter providing for the $895 million bridge facility and $4 billion term facility. Entegris expects to use a portion of the proceeds from the facilities to repay and terminate both Entegris’ and CMC’s existing credit facilities (or amend or otherwise refinance, Entegris’ existing revolving credit facility) substantially concurrently with the completion of the merger. Accordingly, as of September 30, 2021, the combined company would have had approximately $5.6 billion of total debt, after giving pro forma effect to the merger, the refinancing of Entegris’ and CMC’s existing credit facilities and the adjustments set forth under the section entitled “Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page 96.

Following the merger, Entegris’ substantial indebtedness could have adverse effects on Entegris’ financial condition and results of operations, including:

Entegris’ ability to make scheduled payments of the principal of, and to pay interest on or to refinance its indebtedness following the merger will depend on, among other factors, the combined company’s financial positions and performance, as well as prevailing market conditions and other factors beyond its control. The combined business may not continue to generate cash flow from operations in the future sufficient to service Entegris’ debt and make necessary capital expenditures and meet its other liquidity needs. If Entegris is unable to generate such cash flow, it may be required to adopt one or more alternatives, such as selling assets, restructuring debt or obtaining additional equity capital or debt refinancing on terms that may be onerous. The combined company may not be able to engage in any of these activities or engage in these activities on desirable terms, which could result in a default on its debt obligations which, if not cured or waived, could accelerate Entegris’ repayment obligations under all of its outstanding debt which could have a material adverse effect on Entegris’ business, results of operations or financial condition.

In addition, the level and quality of Entegris’ earnings, operations, business and management, among other things, will impact the determination of Entegris’ credit ratings. A decrease in the ratings assigned to Entegris by the ratings agencies may negatively impact Entegris’ access to the debt capital markets and increase Entegris’ cost of borrowing. There can be no assurance that Entegris will be able to obtain any future financing on acceptable terms or at all. In addition, there can be no assurance that Entegris will be able to maintain the current credit worthiness or prospective credit ratings of Entegris or CMC. Any actual or anticipated changes or downgrades in such credit ratings may have a negative impact on the liquidity, capital position or access to capital markets of Entegris.

The agreements that will govern the indebtedness of Entegris following the merger, including the indebtedness to be incurred pursuant to the commitment letter (or any indebtedness that may refinance or replace the bridge facility as set forth in the commitment letter), will contain various affirmative and negative covenants. Such covenants may, subject to certain significant exceptions, restrict the ability of Entegris and certain of its subsidiaries after the merger to, among other things, incur liens, incur debt, engage in mergers, consolidations and acquisitions, transfer assets outside the ordinary course of business, make loans or other investments, pay dividends, repurchase equity interests, make other payments with respect to equity interests, repay or repurchase subordinated debt and engage in affiliate transactions. In addition, such agreements may also contain financial covenants that would require Entegris to maintain certain financial ratios under certain circumstances. The ability of Entegris and its subsidiaries to comply with these provisions after the merger may be affected by events beyond their control. Failure to comply with these covenants could result in an event of default, which, if not cured or waived, could accelerate Entegris’ repayment obligations under all of its outstanding debt, which could have a material adverse effect on Entegris’ business, results of operations or financial condition.

Whether any dividends are declared or paid to stockholders of Entegris following the merger, and the amounts of any such dividends that are declared or paid, are uncertain and depend on a number of factors. If dividends are paid to stockholders of Entegris after the merger, they may not be of the same amount as paid by Entegris or CMC to their respective stockholders before the merger. The board of directors of Entegris will have the discretion to determine the dividend policy of Entegris, which may be impacted by any of the following factors:

Entegris stockholders have no contractual or other legal right to dividends that have not been declared.

Upon consummation of the merger, each CMC stockholder will become a stockholder of Entegris with a percentage ownership of Entegris following the merger that is smaller than such stockholder’s percentage ownership of CMC immediately before the merger. Based on (i) the estimated number of shares of Entegris common stock and CMC common stock issued and outstanding at the close of business on January 25, 2022, the latest practicable date before the date of this proxy statement/prospectus and (ii) the estimated number of shares of Entegris common stock issuable upon the exercise of any converted options, it is expected that CMC stockholders will own approximately 9% of the issued and outstanding shares of Entegris immediately following the completion of the merger. Consequently, former CMC shareholders will have less influence over the management and policies of Entegris than they currently have over the management and policies of CMC.

Entegris’ business will continue to be subject to the risks described in the section entitled “Risk Factors” in Entegris’ Annual Report on Form 10-K for the fiscal year ended December 31, 2020 and in other documents incorporated by reference into this proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 169 for the location of information incorporated by reference into this proxy statement/prospectus.

CMC’s business will continue to be subject to the risks described in the section entitled “Risk Factors” in CMC’s Annual Report on Form 10-K for the year ended September 30, 2021 and in other documents incorporated by reference into this proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 169 for the location of information incorporated by reference into this proxy statement/prospectus.

870 North Commons Drive

Aurora, Illinois 60504

(630) 499-2600

CMC, headquartered in Aurora, Illinois, is a leading global supplier of consumable materials primarily to semiconductor manufacturers. CMC’s products play a critical role in the production of advanced semiconductor devices, helping to enable the manufacture of smaller, faster and more complex devices by its customers. CMC is also a leading provider of performance materials to pipeline operators. CMC’s mission is to create value by delivering high-performing and innovative solutions that solve its customers’ challenges.

CMC common stock is listed on the NASDAQ under the ticker symbol “CCMP.”

For more information about CMC, please visit CMC’s website at https://www.cmcmaterials.com. The information contained on CMC’s website or accessible through it (other than the documents incorporated by reference herein) does not constitute a part of this proxy statement/prospectus or any other report or document on file with or furnished to the SEC. Additional information about CMC is included in the documents incorporated by reference into this proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 169.

129 Concord Road

Billerica, Massachusetts 01821

(978) 436-6500

Entegris, Inc., a Delaware corporation, is a leading global developer, manufacturer and supplier of microcontamination control products, specialty chemicals and advanced materials handling solutions for manufacturing processes in the semiconductor and other high-technology industries. Entegris operates in three segments: Specialty Chemicals and Engineered Materials, Microcontamination Control and Advanced Materials Handling.

Entegris common stock is listed on the NASDAQ under the ticker symbol “ENTG.”

For more information about Entegris, please visit Entegris’ website at http://www.entegris.com. The information contained on Entegris’ website or accessible through it (other than the documents incorporated by reference herein) does not constitute a part of this proxy statement/prospectus or any other report or document on file with or furnished to the SEC. Additional information about Entegris is included in the documents incorporated by reference into this proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 169.

c/o Entegris, Inc.

129 Concord Road

Billerica, Massachusetts 01821

(978) 436-6500

Yosemite Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Entegris, was formed solely for the purpose of facilitating the merger. Merger Sub has not carried on any activities or operations to date, except for those activities incidental to its formation and undertaken in connection with the transactions contemplated by the merger agreement. By operation of the merger, Merger Sub will be merged with and into CMC, with CMC surviving the merger as a wholly owned subsidiary of Entegris.

This proxy statement/prospectus is first being mailed on or about January 28, 2022 and constitutes notice of the special meeting in conformity with the requirements of the DGCL and the amended and restated bylaws of CMC, which are referred to as the CMC bylaws.

This proxy statement/prospectus is being provided to CMC stockholders as part of a solicitation of proxies by the CMC board of directors for use at the special meeting and at any adjournments or postponements of the special meeting. CMC stockholders are encouraged to read the entire document carefully, including the annexes to and documents incorporated by reference into this document, for more detailed information regarding the merger agreement and the transactions contemplated by the merger agreement.

The special meeting will be held virtually via the Internet on March 3, 2022, at 8:00 a.m., Central Standard Time. In light of the ongoing developments related to the COVID-19 pandemic and to protect the health of CMC’s stockholders and the community, the special meeting will be held in a virtual-only format conducted via live audio webcast. Only holders of CMC common stock as of the close of business on the record date are entitled to receive notice of, and vote at, the special meeting via the special meeting website or any adjournment or postponement thereof. CMC stockholders will be able to attend the special meeting via the special meeting website or by proxy, submit questions and vote their shares electronically during the meeting by visiting the special meeting website at www.virtualshareholdermeeting.com/CCMP2022SM. CMC stockholders will need the control number found on their proxy card or voting instruction form in order to access the special meeting website.

At the special meeting, you will be asked to consider and vote on the following proposals:

The CMC board of directors unanimously recommends that CMC stockholders vote:

After careful consideration, the CMC board of directors unanimously (1) determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are advisable, fair to and in the best interests of CMC and its stockholders; (2) approved and adopted the merger agreement, the merger and the other transactions contemplated by the merger agreement; (3) directed that the merger agreement be submitted for adoption at a meeting of CMC stockholders; and (4) resolved to recommend that CMC stockholders vote in favor of the adoption of the merger agreement.

See also the section entitled “The Merger—Recommendation of the CMC Board of Directors; CMC’s Reasons for the Merger” beginning on page 54.

The record date to determine who is entitled to receive notice of and to vote at the special meeting or any adjournments or postponements thereof is January 25, 2022. As of the close of business on January 25, 2022, the latest practicable date before the date of this proxy statement/prospectus, there were 28,575,038 shares of CMC

common stock issued and outstanding and entitled to vote at the special meeting. Each CMC stockholder is entitled to one vote for any matter properly brought before the special meeting for each share of CMC common stock such holder owned at the close of business on the record date. Only CMC stockholders of record at the close of business on the record date are entitled to receive notice of and to vote at the special meeting and any and all adjournments or postponements thereof.

A quorum of stockholders is necessary to conduct the special meeting. The presence, including by proxy, of the holders of a majority of the shares of CMC common stock entitled to vote at the special meeting is necessary to constitute a quorum. Shares of CMC common stock represented at the special meeting and entitled to vote, but not voted, including shares for which a stockholder directs an “abstention” from voting and broker non-votes, will be counted for purposes of determining a quorum. If a quorum is not present, the special meeting will be postponed or adjourned until the holders of the number of shares of CMC common stock required to constitute a quorum attend.

Under the NASDAQ rules, banks, brokers or other nominees who hold shares in “street name” for a beneficial owner of those shares typically have the authority to vote in their discretion on “routine” proposals when they have not received instructions from beneficial owners. However, banks, brokers or other nominees are not allowed to exercise their voting discretion with respect to the approval of matters that the NASDAQ determines to be “non-routine.” Generally, a broker non-vote occurs on an item when (a) a bank, broker or other nominee has discretionary authority to vote on one or more “routine” proposals to be voted on at a meeting of stockholders, but is not permitted to vote on other “non-routine” proposals without instructions from the beneficial owner of the shares and (b) the beneficial owner fails to provide the bank, broker or other nominee with such instructions. Under the NASDAQ rules, “non-routine” matters include the merger agreement proposal (Proposal 1), the compensation proposal (Proposal 2) and the adjournment proposal (Proposal 3). Because none of the proposals to be voted on at the special meeting are routine matters for which brokers may have discretionary authority to vote, CMC does not expect any broker non-votes at the special meeting. As a result, if you hold your shares of CMC common stock in “street name,” your shares will not be represented and will not be voted on any matter unless you affirmatively instruct your bank, broker or other nominee how to vote your shares in one of the ways indicated by your bank, broker or other nominee. It is therefore critical that you cast your vote by instructing your bank, broker or other nominee on how to vote. The NASDAQ rules governing brokers’ discretionary authority will not permit brokers to exercise discretionary authority regarding any of the proposals to be voted on at the special meeting.

Except for the adjournment proposal, the vote required to approve all of the proposals listed herein assumes the presence of a quorum.

As of January 25, 2022, the latest practicable date before the date of this proxy statement/prospectus, CMC directors and executive officers, and their affiliates, as a group, owned and was entitled to vote 257,269 shares of CMC common stock, collectively representing less than 1.0% of the total outstanding shares of CMC common stock. Although none of them has entered into any agreement obligating them to do so, CMC currently expects that all of its directors and executive officers will vote their shares “FOR” the merger agreement proposal, “FOR” the compensation proposal and “FOR” the adjournment proposal. See also the section entitled “Interests of CMC’s Directors and Executive Officers in the Merger” beginning on page 112 and the arrangements described in Part III of CMC’s Annual Report on Form 10-K for the year ended September 30, 2021 and CMC’s Definitive Proxy Statement on Schedule 14A for CMC’s annual meeting filed with the SEC on January 19, 2021, both of which are incorporated into this proxy statement/prospectus by reference.

If you are a stockholder of record, you may vote by proxy through the Internet, by telephone or by mail, or by voting at the special meeting via the special meeting website. For shares held through a bank, broker or other nominee in “street name” instead of as a registered holder, you may vote by submitting your voting instructions to your bank, broker or other nominee. In most instances, you will be able to do this over the Internet, by telephone or by mail as indicated below. Please refer to the information from your bank, broker or other nominee on how to submit voting instructions. If you do not provide voting instructions to your bank, broker or other nominee, your shares of CMC common stock will not be voted on any proposal as your bank, broker or other nominee does not have discretionary authority to vote on any of the proposals to be voted on at the special meeting; see the section entitled “The Special Meeting—Quorum; Abstentions and Broker Non-Votes” beginning on page 41.

Unless revoked, all proxies representing shares entitled to vote that are delivered pursuant to this solicitation will be voted at the special meeting and, where a choice has been specified on the proxy card, will be voted in accordance with such specification. If you are a stockholder of record, proxies submitted over the Internet, by telephone or by mail as described above must be received by 11:59 p.m., Eastern Time, on March 2, 2022. To reduce administrative costs and help the environment by conserving natural resources, CMC asks that you vote through the Internet or by telephone, both of which are available 24 hours a day.

Notwithstanding the above, if you hold your shares in “street name” and you submit voting instructions to your bank, broker or other nominee, your instructions must be received by the bank, broker or other nominee before the deadline set forth in the information from your bank, broker or other nominee on how to submit voting instructions.

If you deliver a proxy pursuant to this proxy statement/prospectus, but do not specify a choice with respect to any proposal set forth in this proxy statement/prospectus, your underlying shares of CMC common stock will be voted on such uninstructed proposal in accordance with the recommendation of the CMC board of directors. CMC does not expect that any matter other than the proposals listed above will be brought before the special meeting and the CMC bylaws provide that the only business that may be conducted at the special meeting are those proposals brought before the meeting pursuant to this proxy statement/prospectus.

Any stockholder giving a proxy has the right to revoke it, including any proxy card you may have previously submitted, before the proxy is voted at the special meeting by any of the following actions:

Attendance virtually at the special meeting will not in and of itself constitute revocation of a proxy. A revocation or later-dated proxy received by CMC after the vote will not affect the vote. CMC’s corporate secretary’s mailing address is: 870 North Commons Drive, Aurora, Illinois 60504, Attention: Corporate Secretary. If the special meeting is postponed or adjourned, it will not affect the ability of holders of CMC common stock of record as of the record date to exercise their voting rights or to revoke any previously granted proxy using the methods described above; however, if a new record date is set for an adjourned meeting, a new quorum will be required to be established.

CMC is soliciting proxies to provide an opportunity to all CMC stockholders to vote on agenda items, whether or not the stockholders are able to attend the special meeting or an adjournment or postponement thereof. In addition to the solicitation of proxies by mail, CMC will request that banks, brokers and other nominee record holders send proxies and proxy material to the beneficial owners of CMC common stock and secure their voting instructions, if necessary. CMC may be required to reimburse those banks, brokers and other nominees on request for their reasonable expenses in taking those actions.

CMC has also retained Innisfree to assist in soliciting proxies and in communicating with CMC stockholders and estimates that it will pay them a fee of approximately $25,000 plus reimbursement for certain fees and expenses. CMC also has agreed to indemnify Innisfree against various liabilities and expenses that relate to or arise out of its solicitation of proxies (subject to certain exceptions). Proxies may be solicited on behalf of CMC or by CMC directors, officers and other employees in person, by mail, by telephone, by facsimile, by messenger, via the Internet or by other means of communication, including electronic communication. Directors, officers and employees of CMC will not be paid any additional amounts for their services or solicitation in this regard.

The special meeting may be accessed via the special meeting website, where CMC stockholders will be able to listen to the special meeting, submit questions and vote online.

You are entitled to attend the special meeting via the special meeting website only if you were a stockholder of record as of the close of business on the record date, or you held your shares beneficially in the name of a bank, broker, trustee or other nominee as of the record date, or you hold a valid proxy for the special meeting. If you were a stockholder of record at the close of business on the record date and wish to attend the special meeting via the special meeting website, you will need the control number on your proxy card. If a bank, broker, trustee or other nominee is the record owner of your shares of CMC common stock, you will need to obtain your specific control number and further instructions from your bank, broker, trustee or other nominee.

You may submit questions during the live audio webcast of the special meeting via the special meeting website. To ensure the special meeting is conducted in a manner that is fair to all stockholders, CMC may exercise discretion in determining the order in which questions are answered and the amount of time devoted to any one question. CMC reserves the right to edit or reject questions it deems inappropriate, redundant or not relevant to the special meeting’s limited purpose.

Technical assistance will be available for stockholders who experience an issue accessing the special meeting. Contact information for technical support will appear on the special meeting website before the start of the special meeting.

SEC rules permit companies and intermediaries such as brokers to satisfy delivery requirements for proxy statements and notices with respect to two or more stockholders sharing the same address by delivering a single proxy statement or a single notice addressed to those stockholders. This process, which is commonly referred to as “householding,” provides cost savings for companies. Some brokers household proxy materials, delivering a single proxy statement or notice to multiple stockholders sharing an address unless contrary instructions have been received from the

affected stockholders. Once you have received notice from your broker that they will be householding materials to your address, householding will continue until you are notified otherwise or until you revoke your consent. If, at any time, you no longer wish to participate in householding and would prefer to receive a separate proxy statement or notice, or if your household is receiving multiple copies of these documents and you wish to request that future deliveries be limited to a single copy, please notify your broker. You can request prompt delivery of a copy of this proxy statement/prospectus by writing to: 870 North Commons Drive, Aurora, Illinois 60504, Attention: Corporate Secretary or by calling (630) 499-2600.

The CMC board of directors will appoint an independent inspector of election for special meeting. The inspector of election will, among other matters, determine the number of shares of CMC common stock represented at the special meeting to confirm the existence of a quorum, determine the validity of all proxies and ballots and certify the results of voting on all proposals submitted to CMC stockholders.

If a quorum is present at the special meeting but there are not sufficient votes at the time of the special meeting to approve the merger agreement proposal, then CMC stockholders may be asked to vote on the adjournment proposal.

At any subsequent reconvening of the special meeting at which a quorum is present, any business may be transacted that might have been transacted at the original meeting and all proxies will be voted in the same manner as they would have been voted at the original convening of the special meeting, except for any proxies that have been effectively revoked or withdrawn before the time the proxy is voted at the reconvened meeting.

If you need assistance voting or in completing your proxy card or have questions regarding the special meeting, please contact Innisfree, the proxy solicitation agent for CMC:

Innisfree M&A Incorporated

501 Madison Avenue, 20th Floor

New York, New York 10022

Stockholders may call toll free: (877) 750-8334

Banks and brokers may call collect: (212) 750-5833

CMC STOCKHOLDERS SHOULD CAREFULLY READ THIS PROXY STATEMENT/PROSPECTUS IN ITS ENTIRETY FOR MORE DETAILED INFORMATION CONCERNING THE MERGER AGREEMENT AND THE MERGER. IN PARTICULAR, CMC STOCKHOLDERS ARE DIRECTED TO THE MERGER AGREEMENT, WHICH IS ATTACHED AS ANNEX A HERETO.

This proxy statement/prospectus is being furnished to you as a stockholder of CMC as part of the solicitation of proxies by the CMC board of directors for use at the special meeting to consider and vote upon a proposal to adopt the merger agreement and approve the transactions contemplated thereby, including the merger, which is attached as Annex A to this proxy statement/prospectus.

The CMC board of directors, after due and careful discussion and consideration, unanimously approved and declared advisable the merger agreement, the merger and the other transactions contemplated by the merger agreement and determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are advisable, fair to and in the best interests of CMC and its stockholders.

The CMC board of directors accordingly unanimously recommends that CMC stockholders adopt the merger agreement, as disclosed in this proxy statement/prospectus and particularly the related narrative disclosures in the sections of this proxy statement/prospectus entitled “The Merger” beginning on page 48 and “The Merger Agreement” beginning on page 69 and as attached as Annex A to this proxy statement/prospectus.

The merger between CMC and Entegris cannot be completed without the affirmative vote of a majority of the outstanding shares of CMC common stock entitled to vote thereon. A failure to vote, a broker non-vote or an abstention will have the same effect as a vote “AGAINST” the proposal to adopt the merger agreement.

IF YOU ARE A CMC STOCKHOLDER, THE CMC BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOU VOTE “FOR” THE MERGER AGREEMENT PROPOSAL (PROPOSAL 1).

Pursuant to Section 14A of the Exchange Act and Rule 14a-21(c) thereunder, CMC is seeking a non-binding, advisory stockholder approval of the compensation of CMC’s named executive officers that is based on or otherwise relates to the merger as disclosed in the section entitled “Interests of CMC’s Directors and Executive Officers in the Merger—Quantification of Potential Payments and Benefits to CMC’s Named Executive Officers” beginning on page 117. The compensation proposal gives CMC stockholders the opportunity to vote, on a non-binding, advisory basis, on the merger-related compensation that will or may be paid or become payable to CMC’s named executive officers.

The CMC board of directors encourages you to read carefully the named executive officer merger-related compensation information disclosed in this proxy statement/prospectus, and, accordingly, CMC is asking CMC stockholders to vote “FOR” the adoption of the following resolution, on a non-binding, advisory basis:

“RESOLVED, that the compensation that will or may be paid or become payable to CMC’s named executive officers, in connection with the merger, and the agreements or understandings pursuant to which such compensation will or may be paid or become payable, in each case as disclosed pursuant to Item 402(t) of Regulation S-K in “Interests of CMC’s Directors and Executive Officers in the Merger—Quantification of Payments and Benefits to CMC’s Named Executive Officers” is hereby APPROVED.”

The vote on the compensation proposal is a vote separate and apart from the votes on the merger agreement proposal and the adjournment proposal. Accordingly, if you are a CMC stockholder, you may vote to approve the merger agreement proposal and/or the adjournment proposal and vote not to approve the compensation proposal, and vice versa. The approval of the compensation proposal is not a condition to the completion of the merger. Because the vote on the compensation proposal is advisory only, it will not affect the obligation of CMC to pay or provide the compensation contemplated by the compensation agreements and arrangements. Accordingly, if the merger is completed, the merger-related compensation will be paid to CMC’s named executive officers to the extent payable in accordance with the terms of the compensation agreements and arrangements even if CMC stockholders fail to approve the advisory vote regarding merger-related compensation.

The CMC board of directors unanimously recommends a vote “FOR” the advisory compensation proposal.

The affirmative vote of a majority of the votes cast at the special meeting on the compensation proposal is required to approve the compensation proposal (meaning the number of votes cast at the special meeting “FOR” the compensation proposal must exceed votes cast “AGAINST” in order for the compensation proposal to be approved). A failure to vote, a broker non-vote or an abstention will have no effect on the outcome of the compensation proposal.

IF YOU ARE A CMC STOCKHOLDER, THE CMC BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOU VOTE “FOR” THE COMPENSATION PROPOSAL (PROPOSAL 2).

The special meeting may be adjourned to another time and place if necessary to permit solicitation of additional proxies if there are not sufficient votes to approve the merger agreement proposal or to ensure that any supplement or amendment to this proxy statement/prospectus is timely provided to CMC stockholders.

CMC is asking its stockholders to authorize the holder of any proxy solicited by the CMC board of directors to vote in favor of any adjournment of the special meeting to solicit additional proxies if there are not sufficient votes to approve the merger agreement proposal or to ensure that any supplement or amendment to this proxy statement/prospectus is timely provided to CMC stockholders.

The CMC board of directors unanimously recommends that CMC stockholders approve the proposal to adjourn the special meeting, if necessary.

Whether or not a quorum is present, the affirmative vote of a majority of the votes cast at the special meeting on the adjournment proposal is required to approve the adjournment proposal (meaning the number of votes cast at the special meeting “FOR” the adjournment proposal must exceed votes cast “AGAINST” in order for the adjournment proposal to be approved). A failure to vote, a broker non-vote or an abstention will have no effect on the outcome of the adjournment proposal.

IF YOU ARE A CMC STOCKHOLDER, THE CMC BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOU VOTE “FOR” THE ADJOURNMENT PROPOSAL (PROPOSAL 3).

The following is a description of material aspects of the merger. While Entegris and CMC believe that the following description covers the material terms of the merger, the description may not contain all the information that is important to you. You are encouraged to read carefully this entire proxy statement/prospectus, including the text of the merger agreement attached to this proxy statement/prospectus as Annex A, for a more complete understanding of the merger. In addition, important business and financial information about each of Entegris and CMC is included in or incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information” beginning on page 169.

Entegris, Merger Sub and CMC have entered into the merger agreement, which provides for the merger of Merger Sub with and into CMC, with CMC surviving the merger as a wholly owned subsidiary of Entegris.

At the effective time, each issued and outstanding share of CMC common stock (other than excluded shares) will be converted into the right to receive (i) $133.00 in cash, which is referred to as the cash consideration, and (ii) 0.4506 of a share of Entegris common stock, which is referred to as the exchange ratio, plus cash in lieu of any fractional shares, which are collectively referred to as the merger consideration. Excluded shares are shares of CMC common stock owned by CMC, Entegris or any of their respective subsidiaries immediately before the effective time and shares of CMC common stock as to which dissenters’ rights have been properly perfected.

No fractional shares of Entegris common stock will be issued upon the conversion of shares of CMC common stock pursuant to the merger agreement. Each holder of shares of CMC common stock who would otherwise have been entitled to receive a fraction of a share of Entegris common stock (after aggregating all shares represented by the certificates and book-entry shares delivered by such holder) will receive, in lieu thereof and upon surrender thereof, a cash payment representing such holder’s proportionate interest, if any, in the proceeds from the sale by the exchange agent (reduced by any fees of the exchange agent attributable to such sale) in one or more transactions of shares of Entegris common stock equal to the excess of (i) the aggregate number of shares of Entegris common stock to be delivered to the exchange agent with respect to the stock portion of the merger consideration over (ii) the aggregate number of whole shares of Entegris common stock to be distributed to the holders of shares of CMC common stock, which is referred to as the excess shares. Holders of CMC common stock who would otherwise have been entitled to receive a fraction of a share of Entegris common stock will not be entitled to dividends, voting rights or any other rights in respect of such fractional shares.

The exchange ratio is fixed, which means that it will not change between now and the date of the merger, regardless of whether the market price of either Entegris common stock or CMC common stock changes. Therefore, the value of the merger consideration will depend on the market price of Entegris common stock at the effective time. The market price of Entegris common stock has fluctuated since the date of the announcement of the merger agreement and will continue to fluctuate from the date of this proxy statement/prospectus to the date of the special meeting, the date the merger is completed and thereafter. The market price of Entegris common stock, when received by CMC stockholders after the merger is completed, could be greater than, less than or the same as the market price of Entegris common stock on the date of this proxy statement/prospectus or at the time of the special meeting. Accordingly, you should obtain current market quotations for Entegris common stock and CMC common stock before deciding how to vote with respect to any of the proposals described in this proxy statement/prospectus. Entegris common stock and CMC common stock are traded on the NASDAQ under the symbols “ENTG” and “CCMP,” respectively.

The CMC board of directors and CMC’s senior management regularly review and assess CMC’s business, operations and financial performance, industry conditions and related developments as they may impact CMC’s long-term strategic plans and objectives. As part of this ongoing evaluation, the CMC board of directors, together with CMC’s senior management, has from time to time considered various potential financial and strategic opportunities to enhance stockholder value, including the evaluation of merger and acquisition transactions of various types and the potential benefits and risks of any such transactions. In addition, CMC’s senior management, from time to time, has engaged in discussions with representatives of other companies regarding such opportunities and updated the CMC board of directors regarding the content of such discussions.

On November 16, 2021 and November 17, 2021, the CMC board of directors held regularly scheduled board and committee meetings in person. At these meetings, the CMC board of directors discussed developments in the electronic materials and specialty chemicals sectors, including a presentation from Goldman Sachs, who has previously acted as a financial advisor to CMC, reviewed and discussed CMC’s standalone strategy and its strategic alternatives, including potential benefits and risks, and approved CMC’s fiscal 2022 capital and operating budget and various compensation and other ordinary course actions relating to CMC’s recently completed 2021 fiscal year.

On November 17, 2021, several hours after the CMC board of directors had concluded its meetings, David Li, the Chief Executive Officer of CMC, received an email from Bertrand Loy, the Chief Executive Officer of Entegris, asking for a call, to which Mr. Li agreed. Mr. Loy then called Mr. Li and expressed Entegris’ interest in exploring a potential acquisition of CMC and informing Mr. Li that he intended to send CMC a written acquisition proposal following the call. While Mr. Li and Mr. Loy had previously engaged in discussions regarding a potential combination between Entegris and CMC in 2016, no such discussions had occurred since that time prior to Mr. Loy’s outreach. Mr. Li stated that he would review any such proposal with the CMC board of directors. Shortly after the call, Mr. Li and William P. Noglows, chairman of the CMC board of directors, received an email from Mr. Loy attaching a preliminary, non-binding indication of interest in Entegris acquiring CMC for $190 per share in cash which is referred to as the November 17 Proposal Letter. The November 17 Proposal Letter indicated that Entegris had obtained a “highly confident” letter from Morgan Stanley to finance the transaction and was prepared to move quickly to a signed transaction. Mr. Li provided a copy of the November 17 Proposal Letter to the CMC board of directors.

On November 18, 2021, Mr. Noglows received a call from Mr. Loy regarding the November 17 Proposal Letter. After a brief discussion, Mr. Noglows indicated that, as Mr. Li had stated, the CMC board of directors would review the November 17 Proposal Letter and get back to Mr. Loy with a response.

On November 22, 2021, the CMC board of directors met by videoconference together with CMC’s senior management and CMC’s outside legal advisor Wachtell, Lipton, Rosen & Katz, which is referred to as, Wachtell Lipton, to review the November 17 Proposal Letter. Representatives from Goldman Sachs and one other financial advisory firm, who also has previously acted as a financial advisor to CMC, each made separate presentations and respectively attended portions of the meeting. Mr. Li updated the CMC board of directors on the brief discussions that he and Mr. Noglows had with Mr. Loy regarding the November 17 Proposal Letter. CMC’s senior management provided its perspective on the strategic rationale for an Entegris acquisition of CMC, and its belief that the transaction had sound industrial logic. Representatives from Goldman Sachs and the other financial advisory firm each made separate presentations regarding the preliminary financial analysis of the Entegris offer, the ability of Entegris to increase its offer as well as an evaluation of other potential acquirors and related considerations. Representatives from Wachtell Lipton provided an overview of legal and fiduciary matters. CMC’s senior management and the CMC board of directors discussed the benefits and risks of the proposed transaction as compared to CMC continuing to pursue its stand-alone strategic plan and also reviewed CMC’s strategic alternatives, which had previously been reviewed at CMC’s regular board meetings the prior week. The CMC board of directors determined that the $190 all-cash offer from Entegris represented a strong initial offer that conveyed a high level of interest but did not fully value CMC and the potential synergies in a transaction. The CMC board of directors also expressed concerns regarding management engaging in a protracted diligence and transaction process due to various strategic initiatives in CMC’s business and the risk of disruption to the business. The CMC board of directors also expressed its view, which was informed by the prior discussions with Entegris in 2016, that a limited and focused diligence process would be important for maximizing price and deal certainty if management engaged with Entegris. The CMC board of directors discussed the potential benefits and risks of reaching out to other potential acquirors, including an evaluation of other potential acquirors by CMC’s senior management and the financial advisory firms and the likelihood of any such potential acquiror making a competitive offer that would be actionable on a comparable timeline and offer comparable closing certainty to the Entegris offer. Based on these discussions, the CMC board of directors determined that the risk of leaks, potentially jeopardizing the Entegris offer and disruption to the business outweighed any potential benefits of reaching out to other potential acquirors at this time, but that the CMC board of directors would retain the flexibility to do such outreach, and would revisit its determination, based on how the situation with Entegris progressed. The CMC board of directors concluded that CMC’s senior management should focus on determining whether a transaction with Entegris at a higher price would be actionable and directed CMC’s senior management to communicate to Entegris that CMC was not prepared to engage unless Entegris improved its

offer price. The CMC board of directors also discussed each of the two potential financial advisory firms that had presented to the CMC board of directors, including feedback from such firms regarding any prior or existing relationships between such firms and Entegris, and selected Goldman Sachs to act as financial advisor in connection with CMC’s evaluation of a potential transaction.

Following the CMC board meeting, Mr. Li called Mr. Loy and indicated that he had reviewed the November 17 Proposal Letter with the CMC board of directors. Mr. Li acknowledged that a combination of Entegris and CMC has sound industrial logic, but noted that CMC was unwilling to engage in transaction discussions unless Entegris improved its offer price. Mr. Loy informed Mr. Li that he would consider Mr. Li’s feedback and discuss it with the Entegris board of directors but he did not commit to improve Entegris’ offer price.

On November 23, 2021, Mr. Li received a call from Mr. Loy during which Mr. Loy informed Mr. Li that Entegris may be willing to increase its offer price if CMC provided certain non-public information in a limited diligence session with members of senior management from both companies that Entegris needed in order to evaluate whether, and to what extent, an increased offer price was supportable. Mr. Li reiterated that CMC was not prepared to engage in transaction discussions or share non-public information with Entegris unless Entegris increased its offer price.

On November 24, 2021, Mr. Li received a call from Mr. Loy during which Mr. Loy informed him that Entegris had considered his feedback and would be increasing its offer price for CMC and that he would be sending a revised proposal following the call. Mr. Loy also indicated that Entegris would not be willing to consider further increasing its offer price for CMC without receiving access to certain non-public information from CMC supporting a higher valuation of CMC. Mr. Loy also expressed his belief that Entegris’ revised offer price fully valued CMC so Mr. Loy did not believe Entegris would be willing to meaningfully increase its offer price. Mr. Li indicated that he would review Entegris’ revised proposal with the CMC board of directors once he received it. Following the call, Mr. Li and Mr. Noglows received Entegris’ revised, non-binding indication of interest in acquiring CMC for $194 per share in cash, which is referred to as the November 24 Proposal Letter.

On November 26, 2021, the CMC board of directors met via videoconference, together with CMC’s senior management and representatives of Goldman Sachs and Wachtell Lipton, to discuss the terms of the November 24 Proposal Letter. Mr. Li updated the CMC board of directors on the recent discussions with Mr. Loy. Representatives of Goldman Sachs reviewed with the CMC board of directors Goldman Sachs’ preliminary financial analysis regarding the updated proposal and Wachtell Lipton reviewed certain legal and fiduciary matters. The CMC board of directors discussed the November 24 Proposal Letter and concluded that CMC’s senior management should continue to seek a higher offer from Entegris. After weighing the benefits and risks of providing diligence information to Entegris at this stage, the CMC board of directors determined that a limited due diligence session with Entegris focused on value driving information would support CMC’s efforts to negotiate a higher offer price from Entegris and, accordingly, authorized limited due diligence with Entegris. The CMC board of directors also had another discussion regarding whether to reach out to any other potential acquirors at this time. The CMC board determined, based on the progress with Entegris to date and the factors considered at its prior meeting, that the risks of outreach continued to outweigh the potential benefits. The CMC board further determined that continuing to negotiate directly with Entegris, while maintaining the flexibility to conduct outreach to third parties and to engage with a third party if such third party submitted a better proposal than that received from Entegris, was the process that would position CMC to obtain the highest reasonable value for CMC’s stockholders.

On November 27, 2021, Mr. Li called Mr. Loy to discuss the November 24 Proposal Letter. Mr. Li indicated that CMC was willing to engage in a limited due diligence session with Entegris on the basis of the November 24 Proposal Letter, similar to the type of diligence session Mr. Loy had previously proposed, with a focus on value driving information such as CMC’s stand-alone operating and financial plan and potential transaction synergies. Mr. Li emphasized, however, that CMC was unlikely to support a transaction priced at $194 per share. Mr. Loy expressed his view that Entegris’ revised offer fully valued CMC, but agreed to proceed with the limited diligence session that Mr. Li was proposing. Mr. Loy also indicated discomfort in taking on additional leverage that would be associated with increased cash consideration, which Mr. Li interpreted as an indication that further increases in the offer price from Entegris may include a stock component. Following the call, CMC provided Entegris with an initial draft mutual non-disclosure agreement to facilitate further engagement between the parties. The proposed non-disclosure agreement included customary “standstill” restrictions but did not include so-called “don’t ask, don’t waive” provisions.

On November 28, 2021, Mr. Li and Mr. Loy spoke to further discuss the engagement process and Mr. Loy expressed his desire to receive more fulsome diligence information from CMC, again citing his concerns about further price increases without additional non-public information supporting the higher valuation. Mr. Loy also again highlighted the attractive premium already reflected in Entegris’ $194 offer price. Mr. Li continued to express that CMC was unlikely to support a transaction at that price, but that CMC was willing to provide diligence information, including selected financial projections and potential transaction synergies, to help support a higher valuation of CMC. Mr. Li and Mr. Loy spoke again later that day and discussed their continued interest in a potential transaction. Mr. Li expressed CMC’s openness to providing Entegris with an increased level of engagement and requested that Entegris provide CMC with a proposed timeline and next steps.

On November 28, CMC received from Entegris’ representatives a proposed timeline and outline of next steps, as well as an initial high -level diligence request list. The proposed timeline included CMC conducting a management meeting and providing key business information in an initial diligence phase followed by a confirmatory diligence phase and merger agreement negotiations. The proposed process also contemplated Entegris progressing its debt financing workstream with Morgan Stanley on a parallel path. Following discussion, Mr. Li and Mr. Loy agreed to tentatively proceed with the proposed work plan subject to confirmation from the CMC board of directors.

On November 30, 2021, the CMC board of directors again met via videoconference with CMC’s senior management and representatives of Goldman Sachs and Wachtell Lipton. Mr. Li updated the CMC board of directors on the recent discussions with Mr. Loy, including Mr. Loy’s comments on the revised offer price and leverage associated with additional cash consideration, as well as the proposed timeline and work plan. Following discussion, the CMC board of directors authorized Mr. Li to continue to proceed with the proposed next steps. The CMC board of directors also instructed Mr. Li to request a revised offer price from Entegris following the initial phase of diligence and prior to proceeding to the confirmatory diligence phase and merger agreement negotiations. The CMC board of directors also expressed its desire to accelerate the proposed timeline if CMC and Entegris reached agreement on valuation so as to avoid potential delay and transaction disruption resulting from the approaching holidays, and the CMC board reiterated its belief that a limited and focused diligence process would be important for maximizing deal certainty and negotiations with Entegris. The CMC board of directors also again discussed whether to reach out to any other potential acquirors but determined that the best process for obtaining the highest reasonable value for CMC stockholders was to continue engaging only with Entegris at this time to optimize those negotiations.

Later that day, Mr. Li confirmed CMC’s willingness to move forward with the proposed management meeting the following day and representatives of Skadden, Arps, Slate, Meagher and Flom, Entegris’ outside legal advisor, which is referred to as Skadden, and Wachtell Lipton had a call to discuss the proposed mutual non-disclosure agreement.

On the morning of December 1, 2021, CMC and Entegris entered into a mutual non-disclosure agreement, which included customary “standstill” restrictions but did not include so-called “don’t ask, don’t waive” provisions. Later the same day, members of CMC’s senior management met virtually with members of Entegris management and representatives from Morgan Stanley and Deloitte & Touche LLP, Entegris’ transaction accounting advisor, during which CMC’s senior management presented an overview of CMC’s business and CMC’s strategic plan, including management forecasts, as well as a discussion of potential synergies in connection with a potential transaction and responses to Entegris’ high priority diligence requests.

On December 2, 2021, Mr. Li and Mr. Loy had a call to follow-up on the prior day’s management meeting and further discussed certain information regarding CMC, the offer price and timeline to signing. Mr. Li expressed his view that the additional information provided in the December 1 management meeting provided support for an increased offer price and requested a revised offer from Entegris and, in light of potential delay and transaction disruption resulting from the approaching holidays, a commitment to work expediently towards a target announcement date no later than December 16, 2021 if the parties moved forward.

On December 3, 2021, Mr. Li and Mr. Noglows received a best and final, non-binding proposal to acquire CMC from Entegris for $200 per share, $133 of which would be paid in cash and $67 of which would be paid in Entegris common stock (based on a fixed exchange ratio to be determined based on Entegris’ five-day volume weighted average trading price ending one day prior to any affected trading or transaction announcement), which is referred to as the December 3 Proposal Letter. Mr. Li received a call from Mr. Loy prior to receiving the December 3 Proposal Letter, during which Mr. Loy emphasized that the December 3 Proposal Letter was Entegris’ best and final offer, including with respect to the cash and stock mix. Mr. Loy also expressed his willingness to target a December 16,

2021 transaction announcement. Mr. Li indicated that the CMC board of directors would review the December 3 Proposal Letter. Mr. Noglows also subsequently received a call from Mr. Loy, during which Mr. Loy further emphasized that the December 3 Proposal was Entegris’ best and final offer.

On December 4, 2021, the CMC board of directors met via a videoconference, at which representatives of CMC’s senior management, Goldman Sachs and Wachtell Lipton were present, to discuss the terms of the December 3 Proposal Letter from Entegris. Mr. Li updated the CMC board of directors on the recent discussions with Mr. Loy and the results of the December 1 management meeting. Management shared its assessment of the revised proposal, including its view that the offer did represent the best and final offer from Entegris. Representatives of Goldman Sachs reviewed with the CMC board of directors Goldman Sachs’ preliminary financial analysis regarding the offer set forth in the December 3 Proposal Letter and Wachtell Lipton discussed certain legal and fiduciary matters. The CMC board of directors discussed the proposed price as well as the proposed cash and stock mix, which differed from the prior all-cash proposals. The CMC board of directors discussed its view that the revised offer from Entegris set forth in the December 3 Proposal Letter provided a substantial premium to CMC stockholders that represented a superior alternative to CMC’s standalone plan and other potential alternatives. The CMC board of directors also discussed the pros and cons of the stock portion of the consideration, including that the CMC board of directors and CMC’s senior management believed there was a compelling strategic rationale for the transaction, that the stock consideration would provide CMC stockholders with the ability to participate in the synergies and value that the CMC board of directors and CMC’s senior management believed would be created in a combination of CMC and Entegris, the fact that the cash and stock offer with an implied value of $200 (based on a fixed exchange ratio to be determined based on Entegris’ five-day volume weighted average trading price ending one day prior to any affected trading or transaction announcement) was materially higher than the prior $194 cash offer and the repeated emphasis from Entegris that this was its best and final offer, including with respect to the stock and cash mix. The CMC board of directors also discussed that the value of the stock consideration would fluctuate with the Entegris stock price and the need for CMC to conduct diligence regarding Entegris. The CMC board of directors discussed the possible benefits and risks of a potential Entegris transaction with representatives of CMC’s senior management, Goldman Sachs and Wachtell Lipton and following these discussions authorized CMC’s senior management to proceed on the terms proposed in the December 3 Proposal Letter and to expeditiously negotiate definitive transaction agreements and complete due diligence, subject to further review and approval by the CMC board of directors. The CMC board of directors discussed with Wachtell Lipton the importance of certain terms to be negotiated in a merger agreement, including CMC termination rights relating to competing proposals and Entegris financing and regulatory commitments.

On December 4, following the CMC board meeting, Mr. Li called Mr. Loy to indicate that the CMC board of directors had agreed to move forward with a potential transaction with Entegris based on the terms of the December 3 Proposal Letter. Mr Li and Mr. Loy further discussed the transaction timing and access to diligence materials. In light of the proposed stock consideration in the December 3 Proposal Letter, Mr. Li and Mr. Loy also discussed the need for CMC to conduct due diligence on Entegris.

Later that day, CMC began providing Entegris with additional non-public diligence materials in a virtual data room. On December 5, 2021, Wachtell Lipton received a draft merger agreement from Skadden.

On December 6, CMC received access to certain non-public diligence materials in a virtual data room in connection with CMC’s diligence of Entegris. CMC also received a relationship disclosure memorandum from Goldman Sachs, which disclosure included certain investment banking relationships that Goldman Sachs had with each of CMC and Entegris.

Following these respective dates until the execution and delivery of the merger agreement, the parties engaged in mutual due diligence investigations of one another, including multiple due diligence discussions over video teleconference with CMC’s senior management and CMC’s representatives, on one hand, and Entegris’ senior management and Entegris’ representatives, on the other. Over the same period, Mr. Li regularly spoke with Mr. Loy to discuss, among other things, updates with respect to the overall process and the plan for retaining CMC talent between signing and closing.

On December 8, 2021, representatives of Wachtell Lipton furnished a revised draft of the merger agreement to Skadden.

Thereafter, Mr. Li and Mr. Loy, as well as representatives of Skadden and Wachtell Lipton, had multiple discussions regarding the terms of the proposed merger agreement, including CMC’s termination rights under the merger

agreement associated with competing acquisition proposals, the treatment of CMC’s dividends during the pendency of the transaction, as well as Entegris’ commitments regarding regulatory and financing related matters under the merger agreement. Representatives of Wachtell Lipton and Skadden exchanged several revised versions of the draft merger agreement reflecting the parties’ discussions. Wachtell Lipton also received a copy of the draft debt commitment letter between Entegris and Morgan Stanley from Skadden.

On December 13, 2021, the CMC board of directors held via videoconference a meeting, at which representatives of CMC’s senior management, Goldman Sachs and Wachtell Lipton were present. At this meeting, Mr. Li and representatives of Wachtell Lipton and Goldman Sachs provided the CMC board of directors with an update on the ongoing discussions and negotiations regarding the potential transaction with Entegris as well as the ongoing diligence investigations. Wachtell Lipton discussed certain legal and fiduciary matters, including a summary of the key transaction terms in the near final merger agreement, the expected timing of regulatory clearances and closing, and a summary of the key open issues that remained the subject of ongoing negotiations. The CMC board determined that CMC’s senior management and its advisors should proceed with finalizing the merger agreement. Mr. Li discussed with the CMC board of directors that he and Mr. Loy would be discussing communication plans later that afternoon and that the CMC board of directors would likely reconvene on December 14. After Goldman Sachs left the meeting, CMC’s senior management also reviewed with the CMC board of directors the terms of the proposed engagement letter with Goldman Sachs which had been substantially negotiated as well as the relationship disclosure memorandum from Goldman Sachs and the CMC Board authorized CMC’s senior management to finalize the engagement letter.

On December 13, 2021, Mr. Li and Mr. Loy spoke by telephone to discuss the communication plan for announcing the transaction in addition to the remaining unresolved issues in the merger agreement. In light of the expectation that the merger agreement would be signed the following day, after market close on December 13, 2021, representatives of Entegris and CMC agreed on a calculation of an exchange ratio of 0.4506 for the stock portion of the merger consideration, which represented $67 based on Entegris’ five-day average volume weighted average trading price ending on December 13, which together with the $133 of cash consideration, represented an implied value of $200 per share.

On December 14, 2021, a meeting of the CMC board of directors, at which representatives of CMC’s senior management, Goldman Sachs and Wachtell Lipton were present, was held via videoconference. Representatives of CMC’s senior management updated the CMC board of directors on the status of the negotiations with Entegris, including that the parties had substantially finalized the merger agreement and resolved all significant open substantive issues with respect to the terms of the potential transaction and discussed the results of their diligence investigation regarding Entegris and management’s views on the transaction. Thereafter, the CMC board of directors listened to a presentation by Mr. Loy regarding his perspective concerning the strategic rationale for the potential transaction. After Mr. Loy departed, representatives of Wachtell Lipton then reviewed with the CMC board of directors its fiduciary duties under applicable law and the material terms of the draft merger agreement. Representatives of Goldman Sachs then reviewed with the CMC board of directors Goldman Sachs’ financial analysis of the potential transaction with Entegris. Following further discussion, representatives of Goldman Sachs then delivered to the CMC board of directors Goldman Sachs’ oral opinion, subsequently confirmed in writing by delivery of Goldman Sachs’ opinion dated as of December 15, 2021, to the effect that, as of such date, and based upon and subject to the assumptions, procedures, factors, qualifications and limitations set forth in Goldman Sachs’ written opinion, the merger consideration to be paid to CMC stockholders pursuant to the merger agreement was fair, from a financial point of view, to CMC stockholders, as further described in the section entitled “—Opinion of CMC’s Financial Advisor” beginning on page 57.

After discussions, including as to the matters discussed below in the section entitled “—Recommendation of the CMC Board of Directors; CMC’s Reasons for the Merger” beginning on page 54 and the matters discussed at prior meetings, the CMC board of directors unanimously determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement were fair to, and in the best interests of, CMC and its stockholders, approved and declared advisable the merger agreement, the merger and the other transactions contemplated by the merger agreement, directed that the merger agreement be submitted for adoption at a meeting of CMC stockholders and resolved to recommend that CMC stockholders vote in favor of the adoption of the merger agreement.

Later in the evening on December 14, 2021, the Entegris board of directors met by videoconference and determined by unanimous vote of those directors present that the merger agreement and the transactions contemplated thereby, including the merger, were advisable and in the best interests of Entegris and its stockholders, and approved the merger agreement and the transactions contemplated thereby, including the merger.

Following the approval of the merger and the merger agreement by the Entegris board of directors and the CMC board of directors, Entegris and CMC finalized and executed the merger agreement on December 14, 2021, and in the morning of December 15, 2021, prior to the opening of trading, issued a joint press release announcing the execution of the merger agreement.

At a meeting held on December 14, 2021, the CMC board of directors unanimously:

In reaching its decision to approve and declare advisable the merger agreement, the merger and the other transactions contemplated by the merger agreement, the CMC board of directors, as described in the section entitled “—Background of the Merger” beginning on page 48, held a number of meetings, consulted with CMC’s senior management and its outside legal and financial advisors, Wachtell Lipton and Goldman Sachs, respectively, and considered the business, assets and liabilities, results of operations, financial performance, strategic direction and prospects of CMC and Entegris. At its meeting held on December 14, 2021, after due consideration and consultation with CMC’s senior management and outside legal and financial advisors, the CMC board of directors unanimously approved and declared advisable the merger agreement, the merger and the other transactions contemplated by the merger agreement and recommended that CMC stockholders vote in favor of the adoption of the merger agreement.

In making its determination, the CMC board of directors focused on a number of factors, including the following:

The CMC board of directors weighed these advantages and opportunities against a number of potentially negative factors in its deliberations concerning the merger agreement and the merger, including:

The CMC board of directors considered all these factors as a whole and, on balance, concluded that they supported a favorable determination to approve the merger agreement and to make its recommendations to CMC stockholders.

In addition, the CMC board of directors was aware of and considered the interests of its directors and executive officers that are different from, or in addition to, the interests of CMC stockholders generally, including the treatment of equity awards held by such directors and executive officers in the merger described in the section entitled “Interests of CMC’s Directors and Executive Officers in the Merger” beginning on page 112 and the obligation of the surviving company to indemnify CMC directors and officers against certain claims and liabilities.

The foregoing discussion of the information and factors that the CMC board of directors considered is not intended to be exhaustive, but rather is meant to include the material factors that the CMC board of directors considered. The CMC board of directors collectively reached the conclusion to approve the merger agreement, the merger and the other transactions contemplated by the merger agreement in light of the various factors described above and other factors that the members of the CMC board of directors believed were appropriate. In view of the complexity and wide variety of factors, both positive and negative, that the CMC board of directors considered in connection with its evaluation of the merger, the CMC board of directors did not find it practical, and did not attempt, to quantify, rank or otherwise assign relative or specific weights or values to any of the factors it considered in reaching its decision and did not undertake to make any specific determination as to whether any particular factor, or any aspect of any particular factor, was favorable or unfavorable to the ultimate determination of the CMC board of directors. In considering the factors discussed above, individual directors may have given different weights to different factors.

The foregoing description of CMC’s consideration of the factors supporting the merger is forward-looking in nature. This information should be read in light of the factors discussed in the section entitled “Cautionary Statement Regarding Forward-Looking Statements” beginning on page 26.

At a meeting of the CMC board of directors, Goldman Sachs rendered its oral opinion, which was subsequently confirmed by delivery of a written opinion, dated December 15, 2021, to the CMC board of directors that, as of such date and based upon and subject to the factors and assumptions set forth in Goldman Sachs’ written opinion, the merger consideration to be paid to the holders (other than Entegris and its affiliates) of shares of CMC common stock pursuant to the merger agreement was fair from a financial point of view to such holders.

The full text of the written opinion of Goldman Sachs, dated December 15, 2021, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex B. Goldman Sachs provided advisory services and its opinion for the information and assistance of the CMC board of directors in connection with its consideration of the merger. The Goldman Sachs opinion is not a recommendation as to how any holder of shares of CMC common stock should vote with respect to the merger proposal or any other matter.

In connection with rendering the opinion described above and performing its related financial analyses, Goldman Sachs reviewed, among other things:

Goldman Sachs also held discussions with members of the senior managements of CMC and Entegris regarding their assessment of the strategic rationale for, and the potential benefits of, the merger and the past and current business operations, financial condition and future prospects of Entegris and with members of CMC’s senior management regarding the past and current business operations, financial condition and future prospects of CMC; reviewed the reported price and trading activity for shares of CMC common stock and Entegris common stock; compared certain financial and stock market information for CMC and Entegris with similar information for certain other companies the securities of which are publicly traded; reviewed the financial terms of certain recent business combinations in the specialty chemicals industry; and performed such other studies and analyses, and considered such other factors, as it deemed appropriate.

For purposes of rendering its opinion, Goldman Sachs, with CMC’s consent, relied upon and assumed the accuracy and completeness of all of the financial, legal, regulatory, tax, accounting and other information provided to, discussed with or reviewed by, it, without assuming any responsibility for independent verification thereof. In that regard, Goldman Sachs assumed with CMC’s consent that the CMC prospective financial information have been reasonably prepared on a basis reflecting the best currently available estimates and judgments of CMC’s senior management. Goldman Sachs has not made an independent evaluation or appraisal of the assets and liabilities (including any contingent, derivative or other off-balance-sheet assets and liabilities) of CMC or Entegris or any of their respective subsidiaries and it has not been furnished with any such evaluation or appraisal. Goldman Sachs has assumed that all governmental, regulatory or other consents and approvals necessary for the consummation of the merger will be obtained without any adverse effect on CMC or Entegris or the expected benefits of the merger in any way meaningful to its analysis. Goldman Sachs has assumed that the merger will be consummated on the terms set forth in the merger agreement, without the waiver or modification of any term or condition the effect of which would be in any way meaningful to its analysis.

Goldman Sachs’ opinion does not address the underlying business decision of CMC to engage in the merger, or the relative merits of the merger as compared to any strategic alternatives that may be available to CMC; nor does it address any legal, regulatory, tax or accounting matters. Goldman Sachs was not requested to solicit, and did not solicit, interest from other parties with respect to an acquisition of, or other business combination with, CMC or any other alternative transaction. Goldman Sachs’ opinion addresses only the fairness from a financial point of view to the holders (other than Entegris and its affiliates) of CMC common stock, as of the date of the opinion, of the merger consideration to be paid to such holders pursuant to the merger agreement. Goldman Sachs’ opinion does not express any view on, and does not address, any other term or aspect of the merger agreement or merger or any term or aspect of any other agreement or instrument contemplated by the merger agreement or entered into or amended in connection with the merger, including the fairness of the merger to, or any consideration received in connection therewith by, the holders of any other class of securities, creditors, or other constituencies of CMC; nor as to the fairness of the amount or nature of any compensation to be paid or payable to any of the officers, directors or employees of CMC, or class of such persons, in connection with the merger, whether relative to the merger consideration to be paid to the holders (other than Entegris and its affiliates) of shares of CMC common stock

pursuant to the merger agreement or otherwise. Goldman Sachs’ opinion was necessarily based on economic, monetary, market and other conditions as in effect on, and the information made available to it as of, the date of the opinion and Goldman Sachs assumed no responsibility for updating, revising or reaffirming its opinion based on circumstances, developments or events occurring after the date of its opinion. Goldman Sachs does not express any opinion as to the prices at which shares of Entegris common stock or CMC common stock will trade at any time or, as to the potential effects of volatility in the credit, financial and stock markets on CMC or Entegris or the merger, or as to the impact of the merger on the solvency or viability of CMC or Entegris or the ability of CMC or Entegris to pay their respective obligations when they come due. Goldman Sachs’ opinion was approved by a fairness committee of Goldman Sachs.

The following is a summary of the material financial analyses delivered by Goldman Sachs to the CMC board of directors in connection with rendering the opinion described above. The following summary, however, does not purport to be a complete description of the financial analyses performed by Goldman Sachs, nor does the order of analyses described represent relative importance or weight given to those analyses by Goldman Sachs. Some of the summaries of the financial analyses include information presented in tabular format. The tables must be read together with the full text of each summary and are alone not a complete description of Goldman Sachs’ financial analyses. Except as otherwise noted, the following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before December 13, 2021 and is not necessarily indicative of current market conditions.

Implied Premium and Multiple Analysis. Goldman Sachs calculated and compared certain premia and multiples using various prices per share of CMC common stock and the implied value of the merger consideration to be paid by Entegris for each share of CMC common stock pursuant to the merger agreement. For purposes of its analysis, Goldman Sachs calculated an implied value of the merger consideration of $197.11, which is referred to as the implied merger consideration value, by multiplying the exchange ratio of 0.4506 pursuant to the merger agreement by $142.28, the closing price for the shares of Entegris common stock on December 13, 2021, and adding $133.00 of cash consideration pursuant to the merger agreement.

Goldman Sachs calculated the following:

The results of these calculations are as follows:

In addition, Goldman Sachs calculated an implied equity value for CMC by multiplying the implied merger consideration value by the number of fully diluted outstanding shares of CMC as provided by CMC’s senior management. Goldman Sachs then calculated an enterprise value for CMC by adding to the implied equity value calculated for CMC, the net debt of CMC as of September 30, 2021 per the latest Form 10-K of CMC for the 2021 fiscal year.

Based on the foregoing, Goldman Sachs calculated the implied enterprise value for CMC as a multiple of (i) historical earnings before interest, taxes, depreciation, and amortization and which is referred to as EBITDA, as adjusted for CMC for the twelve month period ending September 30, 2021, which is referred to as LTM, (ii) estimated EBITDA for CMC for the fiscal year ending September 30, 2022 as reflected in the median estimates published by the Institutional Brokers’ Estimate System, which is referred to as IBES estimates and (iii) estimated EBITDA for CMC for the fiscal year ending September 30, 2022 as reflected in the CMC prospective financial information.