Spero Therapeutics Announces Inducement Grant Under Nasdaq Listing Rule 5635(c)(4)

CAMBRIDGE, Mass., Sept. 03, 2026 (GLOBE NEWSWIRE) -- Spero Therapeutics, Inc. (Nasdaq: SPRO), a clinical-stage biopharmaceutical company focused on advancing next-generation medicines in immunology and inflammation, today announced that the Compensation Committee of Spero's Board of Directors approved a grant, made on September 1, 2026, of an aggregate of 102,000 restricted stock unit awards (RSUs) and 67,600 stock options to new employees under the Spero Therapeutics, Inc. 2019 Inducement Equity Incentive Plan, as amended (2019 Inducement Plan). The stock options and RSUs are being granted as an inducement material to Spero's new employees in accordance with Nasdaq Listing Rule 5635(c)(4).

The 2019 Inducement Plan is used exclusively for the grant of equity awards to individuals who were not previously employees of Spero (or following a bona fide period of non-employment), as a material inducement for such individuals entering into employment with Spero, pursuant to Rule 5635(c)(4) of the Nasdaq Listing Rules.

The shares underlying the option vest as to 25% on September 1, 2027, with the remainder vesting in 36 equal monthly installments thereafter, subject to the employee's continued employment with Spero through the applicable vesting dates. The RSUs will vest in four equal annual installments beginning on September 1, 2027, subject to the employees' continued employment with Spero through the applicable vesting dates. The stock options and the RSUs are subject to the terms and conditions of the 2019 Inducement Plan and the stock option and the RSU agreement covering the grant.

About Spero Therapeutics Spero Therapeutics is a clinical-stage biopharmaceutical company focused on advancing next-generation medicines for patients with serious immune-mediated diseases. The company's lead program, SP001, is a third-generation, Fc-silent anti-CD40L monoclonal antibody being advanced first in IgG4-related disease, with potential for development in additional immunological & inflammatory diseases. For more information, visit www.sperotx.com

Investor Relations Contact: Shai Biran, PhD Spero Therapeutics [email protected]

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