UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of Earliest Event Reported): February 27, 2018

CYRUSONE INC.

(Exact Name of Registrant as Specified in its Charter)

2101 Cedar Springs Road, Suite 900, Dallas, TX 75201

(Address of Principal Executive Office)

Registrant’s telephone number, including area code: (972) 350-0060

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

ITEM 1.01 — Entry into a Material Definitive Agreement.

On February 27, 2018, CyrusOne Inc., a Maryland corporation (the “Company”), CyrusOne GP, a Maryland statutory trust, and CyrusOne LP, a Maryland limited partnership (the “Operating Partnership”), entered into sales agreements (each, a “2018 Sales Agreement”, and collectively, the “2018 Sales Agreements”) with each of Barclays Capital Inc., Deutsche Bank Securities Inc., Goldman Sachs & Co. LLC, Jefferies LLC, KeyBanc Capital Markets Inc., Merrill Lynch, Pierce, Fenner & Smith Incorporated, Morgan Stanley & Co. LLC, Raymond James & Associates, Inc., RBC Capital Markets, LLC, Stifel, Nicolaus & Company, Incorporated and SunTrust Robinson Humphrey, Inc. (each, a “Sales Agent”, and collectively, the “Sales Agents”), pursuant to which the Company may issue and sell from time to time shares (the “Shares”) of its common stock, par value $0.01 per share (the “Common Stock”), having an aggregate gross sales price of up to $500,000,000 (the “Maximum Amount”), pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-211114) filed with the Securities and Exchange Commission on May 4, 2016.

Subject to the terms and conditions of the 2018 Sales Agreements, the Sales Agents will use their commercially reasonable efforts, consistent with their normal trading and sales practices and applicable law and regulations, to sell, on the Company’s behalf, the Shares that may be offered by the Company from time to time under the 2018 Sales Agreements. The sales, if any, of the Shares made under the 2018 Sales Agreements will be made by means of ordinary brokers’ transactions on the NASDAQ Global Select Market or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or, subject to specific instructions of the Company, at negotiated prices. The compensation payable to each Sales Agent for sales of Shares will be a mutually agreed commission that will not exceed, but may be lower than, 2.0% of the gross sales price of the Shares sold by such Sales Agent pursuant to the applicable 2018 Sales Agreement.

Under the terms of the 2018 Sales Agreements, the Company may also sell Shares to any Sales Agent as principal for its own account. If the Company sells Shares to any Sales Agent as principal, it will enter into a separate terms agreement (each, a “Terms Agreement”, and collectively, the “Terms Agreements”) setting forth the terms of such transaction with the applicable Sales Agent.

The Company intends to contribute the net proceeds from any sales of Shares pursuant to the 2018 Sales Agreements, and the Terms Agreements, if any, to the Operating Partnership in exchange for an equivalent number of newly issued operating partnership units in accordance with the partnership agreement of the Operating Partnership. The Operating Partnership intends to use the proceeds contributed by the Company for general corporate purposes, which may include funding future acquisitions, investments or capital expenditures related to recently signed leases, and repaying outstanding indebtedness.

The Company or any Sales Agent may at any time suspend an offering of Shares pursuant to the terms of the applicable 2018 Sales Agreement. The offering of Shares pursuant to any 2018 Sales Agreement will terminate upon the earlier of (i) the issuance and sale of the Shares having an aggregate gross sales price equal to the Maximum Amount under the 2018 Sales Agreements and the Terms Agreements, if any, and (ii) with respect to a particular 2018 Sales Agreement, the termination of such 2018 Sales Agreement by the Company or by the applicable Sales Agent as permitted therein.

The above summary is qualified in its entirety by reference to the Form of 2018 Sales Agreement, which is filed as Exhibit 1.1 hereto and incorporated herein by reference.

The opinion of Venable LLP, relating to the validity of the Common Stock offered and sold pursuant to the 2018 Sales Agreements, is filed herewith as Exhibit 5.1.

The Sales Agents and their respective affiliates have in the past performed commercial banking, investment banking and advisory services for the Company from time to time for which they have received customary fees and reimbursement of expenses and may, from time to time, engage in transactions with and perform services for the Company in the ordinary course of their business for which they may receive customary fees and reimbursement of expenses.

ITEM 1.02 — Termination of a Material Definitive Agreement.

The information included in Item 1.01 of this Current Report on Form 8-K is incorporated by reference into this Item 1.02. Concurrent with the Company’s entry into the 2018 Sales Agreements, the Company terminated the sales agreements (each, a “2017 Sales Agreement” and collectively, the “2017 Sales Agreements”), each dated as of November 2, 2017, among the Company, CyrusOne GP, the Operating Partnership and each of Barclays Capital Inc., Deutsche Bank Securities Inc., Jefferies LLC, KeyBanc Capital Markets Inc., Merrill Lynch, Pierce, Fenner & Smith Incorporated, Raymond James & Associates, Inc., Stifel, Nicolaus & Company, Incorporated and SunTrust Robinson Humphrey, Inc., in accordance with their terms. The terms of the 2017 Sales Agreements are substantially the same as the terms of the 2018 Sales Agreements. Pursuant to the terms of the 2017 Sales Agreements, the Company incurred no early termination penalties in connection with the termination thereof.

ITEM 9.01 — Financial Statements and Exhibits.

(d) Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.