SEC ends Spero Therapeutics (NASDAQ: SPRO) probe as director steps down

Rhea-AI Filing Summary

Spero Therapeutics reported two corporate updates. First, Ankit Mahadevia, MD, resigned from the Board of Directors, its Development Committee, and all officer and director roles at subsidiaries effective January 30, 2026, citing other professional commitments and no disagreements with the company or Board. The company plans to enter into a consulting agreement so he can continue supporting management.

Second, on January 20, 2026, Spero received a letter from the U.S. Securities and Exchange Commission stating the SEC has concluded its investigation and, based on information as of that date, does not intend to recommend an enforcement action against the company. The investigation had been previously disclosed in Spero’s periodic reports.

Positive

• SEC investigation concluded with no enforcement action: On January 20, 2026, the SEC informed Spero that, based on information as of that date, it does not intend to recommend an enforcement action, removing a previously disclosed regulatory uncertainty.

Negative

• None.

Insights

Regulatory and governance analyst

SEC ends its probe with no enforcement action while a director steps down but remains as consultant.

The SEC’s letter dated January 20, 2026 states it has concluded its investigation of Spero Therapeutics and does not intend to recommend an enforcement action. This removes a disclosed regulatory overhang that had been noted in the company’s periodic reports, clarifying its current standing with the SEC.

On governance, Ankit Mahadevia, MD, resigned from the Board, its Development Committee, and subsidiary roles effective January 30, 2026, due to other professional commitments and not due to disagreements. The intent to enter a consulting agreement suggests continuity of access to his experience, though details of scope or duration are not provided here.

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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): January 30, 2026

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, 14th 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))

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

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 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

(b) On January 30, 2026, Ankit Mahadevia, MD notified the Board of Directors (the “Board”) of Spero Therapeutics, Inc. (the “Company”) of his intention to resign from the Board, including from his service on the Development Committee of the Board and from all officer and director positions he holds with any and all subsidiaries of the Company, effective as of January 30, 2026. Dr. Mahadevia’s resignation is as a result of his other professional commitments and not the result of any dispute or disagreement with the Company or the Board on any matter relating to the Company’s operations, policies or practices. The Company thanks Dr. Mahadevia for his years of service since the inception of the Company. The Company and Dr. Mahadevia intend to enter into a consulting agreement, pursuant to which Dr. Mahadevia will be available to provide support to the Company’s management.

Item 8.01 Other Events.

On January 20, 2026, the Company received a letter (the “Letter”) from the U.S. Securities and Exchange Commission (the “SEC”) advising the Company that the SEC has concluded its investigation into the Company and that, based on the information as of the date of the Letter, the SEC does not intend to recommend an enforcement action against the Company at this time. The Letter was provided under the guidelines set out in the final paragraph of Securities Act Release No. 5310. The investigation was previously disclosed by the Company in its periodic reports under the Securities Exchange Act of 1934, as amended.

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: January 30, 2026				SPERO THERAPEUTICS, INC.
				By:		/s/ Esther Rajavelu
						Esther Rajavelu
						President & Chief Executive Officer

FAQ

What board change did Spero Therapeutics (SPRO) disclose in this 8-K?

Spero Therapeutics reported that Ankit Mahadevia, MD, resigned from the Board, the Development Committee, and all officer and director positions at subsidiaries effective January 30, 2026. The company notes his decision stems from other professional commitments, not any disagreement with management or the Board.

Why did Ankit Mahadevia resign from Spero Therapeutics (SPRO) board?

He resigned effective January 30, 2026, due to other professional commitments. The filing specifically states his departure is not the result of any dispute or disagreement with Spero or its Board regarding the company’s operations, policies, or practices, indicating an amicable transition.

Will Ankit Mahadevia continue working with Spero Therapeutics (SPRO)?

Yes. Spero and Dr. Mahadevia intend to enter into a consulting agreement. Under this arrangement, he will be available to provide support to the company’s management, allowing Spero to retain access to his experience even after his board and officer roles end.

What did the SEC communicate to Spero Therapeutics (SPRO) about its investigation?

On January 20, 2026, the SEC sent Spero a letter stating it has concluded its investigation and, based on information as of that date, does not intend to recommend an enforcement action. This letter was issued under guidelines in Securities Act Release No. 5310.

Was the SEC investigation into Spero Therapeutics (SPRO) previously disclosed?

Yes. Spero had previously disclosed the existence of the SEC investigation in its periodic reports under the Securities Exchange Act of 1934. The new letter updates that status, confirming the investigation’s conclusion without a recommendation for enforcement action against the company.

Does the SEC’s letter impose any enforcement action on Spero Therapeutics (SPRO)?

No. The SEC’s January 20, 2026 letter advises that, based on the information available as of that date, the SEC does not intend to recommend an enforcement action against Spero. The correspondence simply confirms the investigation’s conclusion under established SEC guidelines.