UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 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): October 27, 2026

STAG INDUSTRIAL, INC.

(Exact name of registrant as specified in its charter)

100 Federal Street, 29th Floor

Boston, Massachusetts 02110

(Address of principal executive offices, zip code)

Registrant’s telephone number, including area code: (617) 574-4777

Not applicable

(Former name or former address, if changed since last report)

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:

Securities registered pursuant to Section 12(b) of the Act:

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 and 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. ¨

On October 27, 2026, STAG Industrial, Inc., a Maryland corporation (the “Company”), and its operating partnership, STAG Industrial Operating Partnership, L.P., a Delaware limited partnership (the “Operating Partnership”), entered into amendments (collectively, the “Amendments”) to (i) the note purchase agreement, dated as of December 18, 2014, as amended, among the Company, the Operating Partnership and the noteholders named therein, related to the outstanding $80 million of 4.42% senior unsecured notes, due December 30, 2026, and $20 million of 4.42% senior unsecured notes, due February 20, 2027, (ii) the note purchase agreement, dated as of April 10, 2018, among the Company, the Operating Partnership and the noteholders named therein, related to the $100 million of 4.27% senior unsecured notes, due June 13, 2028, and (iii) the note purchase agreement, dated as of July 8, 2021, among the Company, the Operating Partnership and the noteholders named therein, related to the $275.0 million of 2.80% senior unsecured notes, due September 29, 2031, and $50.0 million of 2.95% senior unsecured notes, due September 28, 2033. The Amendments provide for the release of the Company’s property-owning subsidiaries from their respective guaranty instruments if, among other conditions, the subsidiaries no longer guarantee other indebtedness. The other material terms of each of the note purchase agreements remain unchanged.

The foregoing description of the Amendments does not purport to be complete and is qualified in its entirety by reference to the Amendments, copies of which have been filed as Exhibits 10.1, 10.2 and 10.3 hereto, respectively.

The information set forth under Item 1.01 of this report is incorporated herein by reference.

(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.