DIGITAL REALTY TRUST, INC. files 424B7: prospectus (424B)

PROSPECTUS SUPPLEMENT (To Prospectus dated

3,425,031 Digital Realty Trust, Inc.

Common Stock

This prospectus supplement relates to the potential resale from time to time by the selling stockholders identified in this prospectus supplement of some or all of 3,425,031 shares of our common stock, $0.01 par value per share (“common stock”). The registration of the shares of common stock covered by this prospectus supplement does not necessarily mean that any of the shares will be offered or sold by the selling stockholders. The selling stockholders acquired the shares of common stock on October 20, 2026 pursuant to the transactions contemplated in that certain share purchase agreement, by and among us, Digital Titan 2 (PTY) LTD and TDE Luxco (the “Purchase Agreement”). We issued the shares in reliance upon the exemption from registration afforded by Section 4(a)(2) of the Securities Act of 1933, as amended (the “Securities Act”), and are registering such shares pursuant to the Purchase Agreement. For information regarding the Selling Stockholders, please refer to the section entitled “Selling Stockholders” on page S-8 of this prospectus supplement.

We are not selling any shares of common stock under this prospectus supplement and will not receive any proceeds from the resale of shares by the selling stockholders, but we have agreed to pay certain registration expenses. See “Use of Proceeds.”

The selling stockholders identified in this prospectus supplement (which term as used herein includes their pledgees, donees, transferees, or other successors in interest), may offer the securities from time to time as they may determine directly or through underwriters, broker-dealers or agents and in one or more public or private transactions and at fixed prices, prevailing market prices, at prices related to prevailing market prices or at negotiated prices. If the securities are sold through underwriters, broker-dealers or agents, the selling stockholders will be responsible for underwriting discounts or commissions or agents’ commissions. See the sections entitled “Plan of Distribution” and “About this

Prospectus Supplement and the Prospectus” for more information.

We are organized and conduct our operations to qualify as a real estate investment trust (“REIT”), for U.S. federal income tax purposes. To assist us in complying with certain federal income tax requirements applicable to REITs, our charter contains certain restrictions relating to the ownership and transfer of our stock, including an ownership limit of 9.8% (by value or by number of shares, whichever is more restrictive) on the outstanding shares of our common stock.

Our common stock is listed on the New York Stock Exchange under the symbol “DLR”. The last reported sale price of our common stock on the New York

Stock Exchange on October 29, 2026 was $182.91 per share.

Investing in our common stock involves risks. See “ Risk Factors ” beginning on page

S- 6 of this prospectus supplement and the matters discussed in the documents incorporated by reference in this prospectus supplement and the accompanying prospectus.

Neither the U.S. Securities and Exchange Commission (the “SEC”) nor any state securities commission, nor any other regulatory body has approved

Name of Selling Stockholder Number Percentage Number Percentage

Instanz Australia Pty Ltd, in its capacity as trustee for the King Trust 314,248 * 314,248 — —

* less than 1%

(1) Represents (i) 2,015,745 shares of common stock owned by Berkshire Fund IX (OS), L.P. (“Berkshire Fund IX (OS)”), (ii) 825,745 shares of common stock owned by Berkshire Fund IX-A (OS), L.P. (“Berkshire Fund IX-A (OS)”) and (iii) 269,293 shares of common stock owned by Berkshire Investors (OS), L.P. (“Berkshire Investors (OS)” and together with Berkshire Fund IX (OS) and Berkshire Fund IX-A (OS), the “Berkshire Entities”). Ninth

Berkshire Associates (OS) LLC, a Delaware limited liability company (“9BA (OS)”), is the general partner of Berkshire Fund IX (OS) and Berkshire Fund IX-A (OS). The managing members of 9BA (OS) are over 25 Managing Directors and executives (the “Berkshire Principals”) of Berkshire Partners LLC, a Massachusetts limited liability company (“Berkshire Partners”). The general partner of Berkshire Investors (OS) is Seventh

Berkshire Associates GP (OS), Ltd., a Cayman Islands exempted company (“7BA (OS)”). The directors of 7BA (OS) are two of the Berkshire Principals. Berkshire Partners is the investment advisor to Berkshire Fund IX (OS) and Berkshire Fund IX-A (OS) (together, the “Funds”). The Berkshire Entities often

make acquisitions in, and dispose of, securities of an issuer on the same terms and conditions and at the same time. The Berkshire Principals make investment and voting decisions for the

Berkshire Entities by majority in voting interest. Berkshire Partners, the Berkshire Entities, 9BA (OS) and 7BA (OS) may be deemed to constitute a “group” for purposes of Section 13(d) of the Exchange Act, although they do not admit to being part of a group, nor have they agreed to act as part of a group. The address of all the entities and the managing members mentioned above is 200 Clarendon Street, 35th Floor, Boston, Massachusetts 02116-5021.

PLAN OF DISTRIBUTION

The selling stockholders, or their pledgees, donees, transferees, or any of their successors in interest selling the securities received from a named selling stockholder after the date of this prospectus supplement (all of whom may be selling stockholders), may sell the securities from time to time on any stock exchange or automated interdealer quotation system on which the securities are traded, in the over-the-counter market, in privately negotiated transactions or otherwise, at fixed prices that may be changed, at market prices prevailing at the time of sale, at prices related to prevailing market prices or at prices otherwise negotiated. The selling stockholders may sell the securities by one or more of the following methods, without limitation:

• block trades in which the broker or dealer so engaged will attempt to sell the securities as agent but may position and resell a portion of the block as principal to facilitate the transaction, or in crosses in which the same broker acts as agent on both sides;

• purchases by a broker or dealer as principal and resale by the broker or dealer for its own account pursuant to this prospectus supplement;

• privately negotiated transactions;

• short sales;

• through the writing of options on the securities, swaps or other derivatives, whether or not the options or such instruments are listed on an exchange;

• only upon our prior consent, one or more underwritten offerings on a firm commitment or best efforts basis or other purchases by underwriters, brokers, dealers, and agents who may receive compensation in the form of underwriting discounts, concessions or commissions from the selling stockholders and/or the purchasers of the securities for whom they may act as agent;