FRANKLIN STREET PROPERTIES CORP /MA/

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): October 9, 2025

Franklin Street Properties Corp.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code:(781)557-1300

(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 (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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 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.¨

As previously reported, on November 27, 2024, Franklin Street Properties Corp. (the “Company”) entered into a cooperation agreement (the “Cooperation Agreement”) with Converium Capital Inc., Converium Capital Master Fund LP and Converium PGEQ Multi-Strategy Fund L.P. (collectively, ‘‘Converium’’), and Erez REIT Opportunities LP and Erez Asset Management LLC (collectively, “Erez” and together with Converium, the “Stockholder Parties”). The Cooperation Agreement is set forth as Exhibit 10.1 to this current report and is incorporated herein by reference.

As also previously reported, pursuant to the Cooperation Agreement, the Company appointed Bruce J. Schanzer as a member of the Board of Directors of the Company (the “Board”) on November 27, 2024 and Mr. Schanzer was re-elected to the Board at the Company’s 2025