INXN InterXion Holding NV

Filed by InterXion Holding N.V.

Pursuant to Rule 425 under the Securities Act of 1933

Subject Company: InterXion Holding N.V.

Filer’s SEC File No.: 001-35053

Project Interxion - CEO email

From: David Ruberg, CEO

To: All Interxion employees

Subject: Interxion to combine with Digital Realty

Attachment: Press Release

Dear all,

Today we announced that Interxion has entered into a definitive agreement to combine with Digital Realty, a global company that develops and operates data centres across North America, Europe, Latin America, Asia and Australia. Together, we will create a leading global provider of data centre, colocation and interconnection solutions, significantly enhancing our ability to serve our customers on a global scale.

This is a transformational transaction for Interxion and one that could only have come about due to your consistent execution of our long-term strategies and your unrelenting commitment to our customers and culture, which has given us a leading role in the European market.

Digital Realty has a leading footprint in the data centre industry, and this deal will give our combined company’s customers a differentiated and superior European and global platform, providing them with the full spectrum of data centre offerings. It delivers significant strategic, product and customer benefits. You will be able to find out more about these benefits in the attached press release, as well as in the Q&A, which will be published on conneXion once we have met with all the country teams.

Please look for your invitation to the country meetings on Wednesday. These will be led by your local MD. Jan-Pieter Anten and Giuliano di Vitantonio will host meetings in the Netherlands and United Kingdom HQs respectively.

Leadership and next steps

Once the transaction closes, Digital Realty’s CEO, Bill Stein, will serve as CEO of the combined company. I will serve as the Chief Executive of the combined company’s Europe, Middle East & Africa (EMEA) business, which will be named “Interxion, a Digital Realty company” at the close of the transaction. My plan is to transition out of this role at some point within approximately one year of completion of the transaction.

As part of my role, I will lead the combined company’s efforts to organise and execute a programme to identify and develop high-value communities of interest across the combined company’s platform.

Digital Realty Chief Financial Officer, Andy Power, will serve as CFO of the combined company.

The deal is subject to the normal-course approval of Digital Realty and Interxion shareholders, as well as other customary closing conditions, and we anticipate it will close sometime in 2020.

If you have any questions or receive any inquiries from customers, partners or the press, please direct them to your local MD, functional VP or SMT member. We will continue to keep you updated on our progress over the coming weeks and months.

I am deeply proud of the company that Interxion has become and thank you all for everything you have done to drive us to this point. This deal is testament to your success, and I look forward to working with you and our colleagues at Digital Realty to come together to build the world’s pre-eminent data centre provider.

For now, let’s continue to work on business as usual, operating as two fully independent companies. We will continue our focus on delivering on our proven strategy, serving our customers, and working together as a team with courage and passion to deliver another strong year for Interxion.

Kind regards,

David Ruberg, CEO

Additional Information and Where to Find It

This communication is for information purposes only and does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any proxy, vote or approval with respect to the proposed transaction or otherwise, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. In connection with the proposed transactions, DLR intends to file a Registration Statement on Form S-4 with the U.S. Securities and Exchange Commission (the “SEC”), that will include a proxy statement of DLR, which also constitutes a prospectus of DLR. After the registration statement is declared effective by the SEC, DLR intends to mail a definitive proxy statement/prospectus to shareholders of DLR and DLR intends to cause its subsidiary to file a Tender Offer Statement on Schedule TO (the “Schedule TO”) with the SEC and soon thereafter InterXion intends to file a Solicitation/Recommendation Statement on Schedule 14D-9 (the “Schedule 14D-9”) with respect to the tender offer. The tender offer for the outstanding common stock of InterXion referred to in this document has not yet commenced. The solicitation and offer to purchase shares of InterXion’s common stock will only be made pursuant to the Schedule TO and related offer to purchase. This material is not a substitute for the proxy statement/prospectus, the Schedule TO, the Schedule 14D-9 or the Registration Statement or for any other document that DLR or InterXion may file with the SEC and send to DLR’s or InterXion’s shareholders in connection with the proposed transactions.

BEFORE MAKING ANY VOTING OR INVESTMENT DECISION OR DECISION WITH RESPECT TO THE TENDER OFFER, WE URGE INVESTORS OF DLR AND INTERXION TO READ THE REGISTRATION STATEMENT, PROXY STATEMENT/PROSPECTUS, SCHEDULE TO (INCLUDING AN OFFER TO PURCHASE, RELATED LETTER OF TRANSMITTAL AND OTHER OFFER DOCUMENTS) AND SCHEDULE 14D-9, AS EACH MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO TIME, AND OTHER RELEVANT DOCUMENTS FILED BY DLR AND INTERXION WITH THE SEC CAREFULLY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT DLR, INTERXION AND THE PROPOSED TRANSACTIONS.

Investors will be able to obtain free copies of the Registration Statement, proxy statement/prospectus, Schedule TO and Schedule 14D-9, as each may be amended from time to time, and other relevant documents filed by DLR and InterXion with the SEC (when they become available) at http://www.sec.gov, the SEC’s website, or free of charge from DLR’s website (http://www.digitalrealty.com) or by contacting DLR’s Investor Relations Department at (415) 848-9311. These documents are also available free of charge from InterXion’s website (http://www.interxion.com) or by contacting InterXion’s Investor Relations Department at (813) 644-9399.

Participants in the Solicitation

DLR, InterXion and their respective directors and certain of their executive officers and employees may be deemed, under SEC rules, to be participants in the solicitation of proxies from DLR’s and InterXion’s shareholders in connection with the proposed transactions. Information regarding the officers and directors of DLR is included in its definitive proxy statement for its 2019 annual meeting filed with the SEC on April 1, 2019. Information regarding the officers and directors of InterXion and their ownership of InterXion ordinary shares is set forth in InterXion’s Annual Report on Form 20-F, which was filed with the SEC on April 30, 2019. Additional information regarding the persons who may be deemed participants and their interests will be set forth in the Registration Statement and proxy statement/prospectus and other materials when they are filed with SEC in connection with the proposed transactions. Free copies of these documents may be obtained as described in the paragraphs above.

Forward-Looking Statements

InterXion cautions that statements in this communication that are forward-looking, and provide other than historical information, involve risks, contingencies and uncertainties that may impact actual results of operations of DLR, InterXion and the combined company. These forward-looking statements include, among other things, statements about anticipated satisfaction of closing conditions and completion of the proposed transactions contemplated by the purchase agreement between them. Although we believe that the expectations reflected in those forward-looking statements are reasonable, we can give no assurance that those expectations will prove to have been correct. Those statements are made by using various underlying assumptions and are subject to numerous risks, contingencies and uncertainties, including, among others: the ability of DLR and InterXion to obtain the regulatory and shareholder approvals necessary to complete the anticipated combination, on the anticipated timeline or at all; the risk that a condition to the closing of the anticipated combination may not be satisfied, on the anticipated timeline or at all or that the anticipated combination may fail to close; the outcome of any legal proceedings, regulatory proceedings or enforcement matters that may be instituted relating to the anticipated combination;

the costs incurred to consummate the anticipated combination; the possibility that the expected synergies from the anticipated combination will not be realized, or will not be realized within the expected time period; difficulties related to the integration of the two companies; disruption from the anticipated combination making it more difficult to maintain relationships with customers, employees, regulators or suppliers; the diversion of management time and attention on the anticipated combination; adverse changes in the markets in which DLR and InterXion operate or credit markets; and changes in the terms, scope or timing of contracts, contract cancellations, and other modifications and actions by customers and other business counterparties of DLR and InterXion. If one or more of these risks materialize, or if underlying assumptions prove incorrect, actual results may vary materially from those expected. You should not place undue reliance on forward looking statements. For a more complete discussion of these and other risk factors, please see (i) Parent’s filings with the SEC, including its annual report on Form 10-K for the year ended December 31, 2018 and subsequent quarterly reports on Form 10-Q and (ii) InterXion’s filings with the SEC, including its annual report on Form 20-F for the year ended December 31, 2018 and its subsequent reports on Form 6-K. This communication reflects the views of InterXion’s management as of the date hereof. Except to the extent required by applicable law, InterXion undertakes no obligation to update or revise any forward-looking statement.