VSM Versum Materials Inc

Filed by Versum Materials, Inc.

pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-6

under the Securities Exchange Act of 1934

Subject Company: Versum Materials, Inc.

Commission File No.: 1-37664

Date: April 8, 2019

The following are excerpts from a Schedule 14D-9 previously filed by Versum Materials on March 29, 2019 and amended by Amendment No. 1 to Schedule 14D-9 filed by Versum Materials on April 8, 2019.

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Reasons for the Recommendation

The Versum Board unanimously recommends that Versum stockholders reject the Offer and not tender their Shares into the Offer.

In reaching its decision to make the recommendation described above, the Versum Board consulted with Versum’s senior management and its financial and legal advisors at Lazard, Citi and Simpson Thacher, and considered a number of factors, including its knowledge of the business, assets, and liabilities, results of operations, financial performance, strategic direction and prospects of each of Versum and Entegris, as well as the risks in achieving those prospects, and the anticipated effects of the transaction contemplated by the Entegris Merger Agreement, on the one hand, and the transaction contemplated by the Offer, on the other hand. In recommending that Versum stockholders reject the Offer and not tender their Shares into the Offer, the various factors that the Versum Board considered included, among others and not necessarily in order of relative importance, those described below.

The Offer does not constitute a superior proposal under the terms of the Entegris Merger Agreement.

The Versum Board determined that the Offer does not constitute a superior proposal as defined in the Entegris Merger Agreement. In reaching this determination, the Versum Board concluded that the Offer would not permit Versum stockholders the opportunity to share in the benefits expected from being stockholders of the combined company following the Entegris Merger. The Versum Board believes that the Entegris Merger will result in Versum stockholders having the ability to realize greater long-term value than in an all-cash acquisition of Versum by Merck.

The opportunity presented by the Entegris Merger includes the long-term benefits of enhanced scale and scope; diversified product and technology portfolio and an increased number of growth platforms within high-growth end-markets; the potential to compete more effectively; expected generation of cost synergies, including synergies related to selling, general and administrative expenses and supply chain synergies; expected realization of revenue growth synergies from cross-selling and product co-optimization, with further potential synergies relating to capital expenditures; expected treatment of the Entegris Merger as a tax-free reorganization for U.S. federal income tax purposes; ability to expand in key geographies; the expectation to enhance the resilience of the combined company’s business model, improve predictability of earnings and mitigating potential downside risks; the ability of the combined company to consider other value creating strategic opportunities at the right time; and the flexibility to invest, make acquisitions, and return capital to stockholders, while enjoying greater earnings stability and margin growth potential—all of which the Versum Board believes are unique to the planned merger of equals with Entegris. In this regard, the Versum Board noted that the Offer does not afford Versum stockholders any of these benefits and may have significant tax consequences for certain stockholders.

The Versum Board believes that the Offer Price is below the price that prospective acquirors would be willing to pay in a potential acquisition of Versum.

The Versum Board has not made a decision to sell Versum. However, the Versum Board believes, based on the financial analyses of Versum’s financial advisors and the premiums and financial multiples paid in relevant precedent transactions, that the Offer Price is substantially below the price that prospective acquirors would be willing to pay if the Versum Board were to decide to sell Versum, whether now or in the future. As described in more detail in the investor presentation filed by Versum with the SEC on April 1, 2019 and filed as Exhibit (a)(3) to this Statement, as amended by a second filing with the SEC on April 8, 2019 and filed as Exhibit (a)(4) to this Statement, both of which are incorporated herein by reference, the EV / LTM Adjusted EBITDA multiple for the Offer is 13.1x and the target LTM Adjusted EBITDA margin represented by the Offer is 33%, while recent strategic acquisitions of best-in-class speciality materials businesses reflect EV / LTM Adjusted EBITDA multiples ranging from 13.3x to 20.4x with target LTM Adjusted EBITDA margins ranging from 11% to 30%.

The Offer significantly undervalues Versum’s long-term prospects, in particular in light of the Entegris Merger.

The consideration in the Entegris Merger will consist wholly of shares of the combined company, received in a transaction expected to be treated as a tax-free reorganization for U.S. federal income tax purposes. Therefore, the Entegris Merger offers Versum stockholders the opportunity to participate in the long-term appreciation in the value of the combined company, while no similar opportunity is afforded by the Offer. The Versum Board determined that the Offer significantly undervalues Versum’s long-term prospects, in particular in light of the opportunity to share in the benefits expected from being stockholders of the Combined Company following the Entegris Merger, including the following:

The Offer is highly conditional and places Versum and its stockholders at substantial risk that it will never be consummated.

The Offer is highly conditional and Merck has reserved the ability to change the conditions of the Offer. All of the conditions to the Offer are for the sole benefit of Merck and its affiliates and may be asserted by Merck in its sole discretion regardless of the circumstances (including any action or omission by Merck) giving rise to any such conditions, or may be waived by Merck in its sole discretion in whole or in part at any time or from time to time before the Expiration Date. In other words, Merck claims that Merck may assert that a condition has not been satisfied, even if the failure of such condition to be satisfied was caused by Merck’s own action or inaction, and such determination will not be subject to challenge.

Moreover, Merck expressly reserves the right to make any change in the terms of, or conditions to, the Offer. Merck’s ability to change the conditions to the Offer at any time means that the Offer could become subject not only to modified conditions, but also to additional unknown conditions.

As described in “Item 2. Identity and Background of Filing Person—The Conditions to the Offer” above and in Annex A attached hereto, the Offer is subject to numerous conditions, including, among others, the following conditions:

In addition to the foregoing, Merck also does not need to consummate the Offer if any of the following conditions, among others, exists (even if subsequently cured, and regardless of whether Merck or Offeror causes or contributes to such conditions):

The Versum Board believes that these conditions to Merck’s obligation to consummate the Offer, many of which vest a great deal of discretion in Merck, create significant risks as to whether the Offer can be completed and as to the timing for completion. More specifically, many of the conditions to the Offer are broad and are subject to Merck’s sole discretion, and some conditions are not qualified by any materiality standard, making it possible for Merck to determine that a condition is not satisfied and decline to close the Offer (subject to compliance with the terms of the Offer and all relevant laws and regulations).

The effect of the foregoing is that Versum stockholders cannot be assured that Merck will consummate the Offer. Uncertainty as to the likelihood of consummation of the Offer is of particular concern because if the Entegris Merger Agreement was terminated and the Offer was not consummated, it is possible that neither Entegris nor any other third party would be interested in combining with Versum (in which case the trading prices of the Versum common stock on the NYSE could return to levels before the announcement of the Entegris transaction or lower) or, if interested, would be willing to pay consideration that is equivalent to or greater than the consideration Versum stockholders would receive in the Entegris Merger.

Merck has discretion to extend the Offer indefinitely.

Merck has stated that it may, in Merck’s sole discretion, extend the Offer from time to time for any reason. Versum stockholders have no assurance that they will ever receive payment for Shares tendered in a timely fashion. Merck has thus given itself broad discretion to disrupt Versum’s business indefinitely without any assurance as to when it may provide value to Versum stockholders.

Neither the HSR Condition, CFIUS Clearance nor the condition that all other required foreign antitrust or competition clearances have been obtained is satisfied as of the date of this Statement, and it is uncertain if and when these conditions will be satisfied. In particular, the CFIUS Clearance and the required foreign antitrust and competition clearances are unlikely to be obtained prior to the initial expiration date of the Offer.

Certain conditions to the Offer may not be capable of being, or are unlikely to be, satisfied.

The No Impairment Condition is drafted in extremely broad and general terms and, according to the terms of the Offer, Merck may decide in its reasonable judgment whether this condition has been met. Accordingly, even assuming that the numerous other conditions to the Offer could be satisfied, this condition creates uncertainty regarding whether Merck would consummate the Offer given that any number of otherwise insignificant events or circumstances could be deemed by Merck to impair Merck’s ability to acquire the shares of Versum common stock or to otherwise diminish the expected value to Merck of the acquisition of Versum, and thereby cause this condition not to be satisfied.

Merck has not made any commitment to extend the Offer long enough to permit the regulatory approval conditions to be satisfied.

Once the Offer expires on June 7, 2019, and if any condition to the Offer has not been satisfied, Merck is free to terminate the Offer and walk away from the Offer without purchasing any shares of Versum common stock. Even though Merck is likely aware that it will take several months for the required antitrust or competition clearances and CFIUS Clearance to be obtained, there is no commitment by Merck to extend and keep open the Offer until such conditions have been satisfied. Even if Merck continuously extends the Offer until the CFIUS Clearance and the required regulatory clearances have been obtained, Merck may adversely modify the terms of its Offer, including the price, in connection with any of these extensions of the Offer.

Entegris is bound by the Entegris Merger Agreement and cannot terminate the Entegris Merger Agreement and walk away from the Entegris Merger except under narrowly specified circumstances negotiated with Versum as set forth in the Entegris Merger Agreement. Merck, on the other hand, may elect to walk away from the Offer after any scheduled expiration date for the Offer and has not made any commitment to the contrary.

Other factors.

In addition to the factors set forth above, in reaching its determinations to recommend that Versum stockholders reject the Offer, the Versum Board considered various factors that weighed positively in favor of the Entegris Merger Agreement and the transactions contemplated by the Entegris Merger Agreement, including, among others:

The Versum Board also considered a number of potentially countervailing factors and risks, including, without limitation:

The Versum Board determined that overall these potential countervailing factors and risks associated with the Offer were outweighed by the other factors and risks considered by the Versum Board that weighed negatively against the Offer as described above, as well as by the benefits that the Versum Board expects Versum stockholders to realize as a result of the Entegris Merger. The Versum Board acknowledged that there can be no assurance about future results, including results considered or expected as disclosed in the foregoing reasons. The foregoing description is forward-looking in nature and should be read in light of the factors discussed in the section entitled “Item 8. Additional Information—Cautionary Statement Regarding Forward-Looking Statements” of this Statement.

ACCORDINGLY, BASED ON THE FOREGOING REASONS, THE VERSUM BOARD RECOMMENDS THAT HOLDERS OF SHARES OF VERSUM COMMON STOCK REJECT THE OFFER AND NOT TENDER ANY OF THEIR SHARES PURSUANT TO THE OFFER.

The foregoing discussion of the information and factors considered by the Versum Board is not meant to be exhaustive, but includes the material information, factors, and analyses considered by the Versum Board in reaching its conclusions and recommendations. The members of the Versum Board evaluated the various factors listed above in light of their knowledge of the business, financial condition, and prospects of Versum and Entegris and considered the advice of the Versum Board’s financial and legal advisors. In light of the number, complexity and variety of factors that the Versum Board considered, the members of the Versum Board did not find it practicable to assign relative weights to the foregoing factors. The recommendation of the Versum Board was made after considering the totality of the information and factors involved. Individual members of the Versum Board may have given different weight to different factors.

In light of the factors described above, the Versum Board has determined that the Offer is not in the best interests of Versum stockholders. Therefore, the Versum Board recommends that Versum stockholders reject the Offer and not tender any of their shares of Versum common stock to Merck pursuant to the Offer.