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): May 17, 2016

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:

On May 17, 2016, Spire Inc. (“Spire”) issued and sold 2,185,000 shares of Spire’s common stock, par value $1.00 per share (the “Common Stock”), at a public offering price of $63.05 per share pursuant to an Underwriting Agreement, dated May 12, 2016, between Spire and Morgan Stanley & Co. LLC. The Common Stock has been issued pursuant to Spire’s Registration Statement on Form S-3 (Registration No. 333-190388) (as amended, the “Registration Statement”), which became effective upon filing with the Securities and Exchange Commission, and the related Prospectus dated June 3, 2014 and Prospectus Supplement dated May 12, 2016. A copy of the Underwriting Agreement and opinion related to the Common Stock are attached hereto as exhibits and are expressly incorporated by reference herein and into the Registration Statement.

The foregoing description of the terms of the Underwriting Agreement is qualified in its entirety by reference to the actual terms of the Underwriting Agreement, a copy of which is attached hereto as Exhibit 1.1.

The following exhibits are filed as part of this report:

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.

Exhibit Index