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 13, 2025

SPERO THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Delaware

001-38266

46-4590683

(State or other jurisdiction

of incorporation)

(Commission
File Number)

(I.R.S. Employer
Identification No.)

675 Massachusetts Avenue, 14^th Floor

Cambridge, Massachusetts

02139

(Address of principal executive offices)

(Zip Code)

Registrant’s telephone number, including area code (857) 242-1600

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:

☐	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))

Title of each class

Trading

Symbol(s)

Name of each exchange

on which registered

Common Stock, $0.001 par value

SPRO

The Nasdaq Global Select Market

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 2.02

Results of Operations and Financial Condition.

On May 13, 2025, Spero Therapeutics, Inc. (the “Company”) issued a press release announcing its results for the first quarter ended March 31, 2025. A copy of the press release issued in connection with the announcement is furnished as Exhibit 99.1 to this Current Report on Form 8-K.

The information contained in this Item 2.02 and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing.

Item 9.01

Financial Statements and Exhibits

(d) Exhibits


Exhibit No.		Description

99.1		Press release issued by Spero Therapeutics, Inc. on May 13, 2025

104		Cover Page Interactive Data File (embedded within the Inline XBRL document and incorporated as Exhibit 101)

SIGNATURE

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.


Date: May 13, 2025	SPERO THERAPEUTICS, INC.

	By:	/s/ Esther Rajavelu
		Esther Rajavelu
		President and Chief Executive Officer, Chief Financial Officer, Chief Business Officer and Treasurer

Spero Therapeutics, Inc. 8-K