Versum Materials (VSM) 8-K Versum Materials Announces Date for Special Meeting of Stockholders to Vote

Exhibit 99.1

News Release

Versum Materials Announces Date for Special Meeting of Stockholders to Vote

on the Merger Agreement with Merck KGaA, Darmstadt, Germany

Tempe, Arizona, May 8, 2019 (Businesswire) - Versum Materials, Inc. (NYSE: VSM), a leading specialty materials and equipment supplier to the semiconductor industry, today announced that it will hold a special meeting of its stockholders at its corporate headquarters, 8555 South River Parkway, Tempe, Arizona 85284, on June 17, 2019, beginning at 2:00 p.m., local time. At the special meeting, stockholders will be asked to take action to, among other things, adopt the Agreement and Plan of Merger, dated as of April 12, 2019 (the “merger agreement”), by and among Versum Materials, Merck KGaA, Darmstadt, Germany and EMD Performance Materials Holding, Inc. The board of directors of Versum Materials unanimously recommends that Versum Materials’ stockholders vote to adopt the merger agreement at the special meeting.

Only stockholders of record at the close of business on May 13, 2019 (the “record date”), will be entitled to receive notice of and to vote at the special meeting and any adjournments or postponements thereof. Under the terms of the merger agreement, each share of Versum Materials common stock, par value $1.00 per share (“Versum common stock”) issued and outstanding immediately prior to the effective time of the merger (other than shares of Versum common stock owned by Versum Materials, Merck KGaA, Darmstadt, Germany, and its subsidiaries or certain other excluded holders pursuant to the terms of the merger agreement) automatically will be converted into the right to receive $53.00 in cash, without interest and less any applicable withholding taxes.

The transaction is expected to close in the second half of 2019, subject to the approval of stockholders at the special meeting, regulatory clearances and the satisfaction of other customary closing conditions.

About Versum Materials

Versum Materials, Inc. (NYSE: VSM) is a leading global specialty materials company providing high-purity chemicals and gases, delivery systems, services and materials expertise to meet the evolving needs of the global semiconductor and display industries. Derived from the Latin word for “toward,” the name “Versum” communicates the company’s deep commitment to helping customers move toward the future by collaborating, innovating and creating cutting-edge solutions.

A global leader in technology, quality, safety and reliability, Versum Materials is one of the world’s leading suppliers of next-generation CMP slurries, ultra-thin dielectric and metal film precursors, formulated cleans and etching products, and delivery equipment that has revolutionized the semiconductor industry. Versum Materials reported fiscal year 2018 annual sales of about U.S. $1.4

billion, has approximately 2,300 employees and operates 14 major facilities in Asia and the North America. It is headquartered in Tempe, Arizona. Versum Materials had operated for more than three decades as a division of Air Products and Chemicals, Inc. (NYSE:APD).

For additional information, please visit http://www.versummaterials.com.

Cautionary Statement Regarding Forward-Looking Statements

This communication may contain forward-looking statements based on current assumptions and forecasts made by Versum Materials, Inc. (“Versum”) management. Various known and unknown risks, uncertainties and other factors could lead to material differences between the actual future results, financial situation, development or performance of the company and the estimates given here. These factors include the following: Merck KGaA, Darmstadt, Germany’s ability to successfully complete the proposed acquisition of Versum or realize the anticipated benefits of the proposed transaction in the expected time-frames or at all; Merck KGaA, Darmstadt, Germany’s ability to successfully integrate Versum’s operations into those of Merck KGaA, Darmstadt, Germany; such integration may be more difficult, time-consuming or costly than expected; the failure to obtain Versum’s stockholders’ approval of the proposed transaction; the failure of any of the conditions to the proposed transaction to be satisfied; revenues following the proposed transaction may be lower than expected; operating costs, customer loss and business disruption (including, without limitation, difficulties in maintaining relationships with employees, customers, clients or suppliers) may be greater than expected following the proposed transaction; the retention of certain key employees at Versum; risks associated with the disruption of management’s attention from ongoing business operations due to the proposed transaction; the outcome of any legal proceedings related to the proposed transaction; the impact of the proposed transaction on Versum’s credit rating; the parties’ ability to meet expectations regarding the timing and completion of the proposed transaction; delays in obtaining any approvals required for the proposed transaction or an inability to obtain them on the terms proposed or on the anticipated schedule; the impact of indebtedness incurred by Merck KGaA, Darmstadt, Germany, in connection with the proposed transaction; the effects of the business combination of Versum and Merck KGaA, Darmstadt, Germany, including the combined company’s future financial condition, operating results, strategy and plans; and other factors discussed in Merck KGaA, Darmstadt, Germany’s public reports which are available on the Merck KGaA, Darmstadt, Germany website at www.emdgroup.com or in Versum’s Annual Report on Form10-K filed with the U.S. Securities and Exchange Commission (the “SEC”) for the fiscal year ended on September 30, 2018 and Versum’s other filings with the SEC, which are available at http://www.sec.gov and Versum’s website at www.versummaterials.com. Except as otherwise required by law, Versum assumes no liability whatsoever to update these forward-looking statements or to conform them to future events or developments. Readers are cautioned not to place undue reliance on these forward-looking statements that speak only as of the date hereof.

Additional Important Information and Where to Find It

This communication relates to the proposed merger transaction involving Versum and Merck KGaA, Darmstadt, Germany. In connection with the proposed merger, Versum and Merck KGaA, Darmstadt, Germany intend to file relevant materials with the SEC, including Versum’s proxy statement on Schedule 14A (the “Proxy Statement”). This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval, and is not a substitute for the Proxy Statement or any other document that Versum or Merck KGaA, Darmstadt, Germany, may file with the SEC or send to Versum’s stockholders in connection with the proposed merger. STOCKHOLDERS OF VERSUM ARE URGED TO READ ALL RELEVANT DOCUMENTS FILED WITH THE SEC, INCLUDING THE PROXY STATEMENT, WHEN THEY BECOME AVAILABLE BECAUSE THEY

WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED MERGER. Investors and security holders will be able to obtain the documents (when available) free of charge at the SEC’s web site, http://www.sec.gov, or Versum’s website at http://investors.versummaterials.com or by phone at484-275-5907.

Participants in Solicitation

Versum, Merck KGaA, Darmstadt, Germany and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the holders of Versum common stock in respect of the proposed transaction. Information about the directors and executive officers of Versum is set forth in Versum’s Annual Report on Form 10-K for the fiscal year ended September 30, 2018, which was filed with the SEC on November 21, 2018, and the proxy statement for Versum’s 2019 annual meeting of stockholders, which was filed with the SEC on December 20, 2018. Information about the directors and executive officers of Merck KGaA, Darmstadt, Germany is set forth on Schedule I of the Schedule 14A filed by Merck KGaA, Darmstadt, Germany with the SEC on March 22, 2019. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the Proxy Statement and other relevant materials to be filed with the SEC in respect of the proposed transaction when they become available.

Versum Materials, Inc.

Investor Inquiries:

Soohwan Kim, CFA,602-282-0957

Soohwan.Kim@versummaterials.com

or

Media Inquiries:

Tiffany Elle,480-282-6475

Tiffany.Elle@versummaterials.com