INXN InterXion Holding NV

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

Amendment No. 3

Tender Offer Statement under Section 14(d)(1) or 13(e)(1)

of the Securities Exchange Act of 1934

(Rule 14d-100)

InterXion Holding N.V.

(Name of Subject Company (Issuer))

Digital Intrepid Holding B.V.

(Name of Filing Person (Offeror))

An indirect subsidiary of

Digital Realty Trust, Inc.

(Name of Filing Person (Ultimate Parent of Offeror))

(Names of Filing Persons (identifying status as offeror, issuer or other person))

Ordinary shares, nominal value €0.10 per share

(Title of Class of Securities)

N47279109

(CUSIP Number of Class of Securities)

Andrew P. Power

Chief Financial Officer

Digital Realty Trust, Inc.

Four Embarcadero Center, Suite 3200

San Francisco, CA 94111

(415) 738-6500

(Name, address, and telephone number of person authorized to receive notices and communications on behalf of filing persons)

with copies to:

CALCULATION OF FILING FEE

Check the appropriate boxes below to designate any transactions to which the statement relates:

Check the following box if the filing is a final amendment reporting the results of the tender offer: ☒

If applicable, check the appropriate box(es) below to designate the appropriate rule provision(s) relied upon:

This Amendment No. 3 (this “Amendment”) amends and supplements the Tender Offer Statement on Schedule TO initially filed with the U.S. Securities and Exchange Commission (the “SEC”) on January 29, 2020, as amended by Amendment No. 1 to the Schedule TO filed with the SEC on February 28, 2020 and by Amendment No. 2 to the Schedule TO filed with the SEC on March 9, 2020 (together with any further amendments and supplements thereto, the “Schedule TO”) by Digital Realty Trust, Inc., a Maryland corporation (“DLR”), and Digital Intrepid Holding B.V. (formerly known as DN 39J 7A B.V.), a private limited liability company (besloten vennootschap met beperkte aansprakelijkheid) organized under the laws of the Netherlands and an indirect subsidiary of DLR (“Buyer”), relating to the offer by Buyer to exchange (the “offer”) shares of DLR common stock, par value $0.01 per share (“DLR common stock”), for all of the outstanding ordinary shares, nominal value €0.10 per share (the “INXN shares”), of InterXion Holding N.V., a public limited liability company (naamloze vennootschap) organized under the laws of the Netherlands (“INXN”), upon the terms and subject to the conditions set forth in the Exchange Offer Prospectus, dated January 29, 2020, filed as Exhibit (a)(3) to the Schedule TO (the “Exchange Offer Prospectus”) and the related letter of transmittal filed as Exhibit (a)(1)(A) to the Schedule TO. Capitalized terms used, but not otherwise defined, in this Amendment shall have the meanings ascribed to them in the Exchange Offer Prospectus. This Amendment is being filed to reflect certain updates as reflected below.

Items 1 and 4.

The Exchange Offer Prospectus and Items 1 and 4 of the Schedule TO, to the extent such Items incorporate by reference the information contained in the Exchange Offer Prospectus referenced below, are hereby amended and supplemented as follows:

The information set forth in the sections of the Exchange Offer Prospectus entitled “Summary” and “The Offer” are hereby amended and supplemented by inserting the following paragraphs at the end of the section:

“At 12:01 a.m. (New York City Time) on March 12, 2020, the subsequent offering period expired. American Stock Transfer & Company, LLC, the exchange agent, has advised Buyer that, as of the expiration time of the subsequent offering period, a total of 70,862,736 INXN shares, collectively representing approximately 92.26% of the total outstanding INXN shares, were validly tendered in the offer.

Buyer has accepted for payment and expects to promptly pay for all INXN shares validly tendered prior to the expiration time of the subsequent offering period.

The offer has concluded, and DLR and Buyer expect to consummate the post-offer reorganization pursuant to the purchase agreement as promptly as practicable.”

Note Regarding Forward-Looking Statements

DLR and INXN caution 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 and INXN. These forward-looking statements include, among other things, statements about 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 outcome of any legal proceedings, regulatory proceedings or enforcement matters that may be instituted relating to the combination; the costs incurred to consummate the combination; the possibility that the expected synergies from the 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 combination making it more difficult to maintain relationships with customers, employees, regulators or suppliers; the diversion of management time and attention on the combination; adverse changes in the markets in which DLR and INXN 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 INXN. 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) DLR’s filings with the SEC, including its Registration Statement on Form S-4 filed with the SEC on December 6, 2019, including Amendment No. 1 to its Registration Statement on Form S-4 filed with the SEC on January 7, 2020 and Amendment No. 2 to its Registration Statement on Form S-4 filed with the SEC on January 24, 2020, and its annual report on Form 10-K for the year ended December 31, 2019 and (ii) the documents INXN has filed with or furnished to 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 DLR’s management as of the date hereof. Except to the extent required by applicable law, DLR undertakes no obligation to update or revise any forward-looking statement.

SIGNATURES

After due inquiry and to the best of their knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: March 12, 2020