Spero Therapeutics SEC filings document the regulatory record of a clinical-stage biopharmaceutical company focused on immunology and inflammation. The filings identify SPRO common stock as listed on the Nasdaq Global Select Market and show the company’s headquarters in Cambridge, Massachusetts.
Quarterly reports on Form 10-Q provide Spero’s financial statements and notes, including disclosures on share-based compensation plans and at-the-market offering activity when applicable. Current reports on Form 8-K have covered operating results, license agreements, FDA approval disclosures for Utebzi, equity plan approvals, charter amendments, shelf registration activity and at-the-market sale agreements.
Spero’s DEF 14A proxy statement is relevant for governance matters submitted to stockholders, including equity plan information and annual meeting voting items. Registration-related filings and prospectus materials are also important because the company has used shelf registration and at-the-market structures to describe potential securities offerings.
Spero Therapeutics is asking stockholders to vote at its 2026 virtual annual meeting on June 23, 2026. The meeting will be held via live audio webcast, with holders of common stock as of April 24, 2026 entitled to vote.
Key items include electing two directors, ratifying PricewaterhouseCoopers LLP as auditor for 2026, an advisory vote on executive compensation, doubling authorized common stock from 120,000,000 to 240,000,000 shares, and approving the 2026 Stock Incentive Plan. As of the record date, 57,901,493 common shares were outstanding. The proxy also details board structure, committee responsibilities, insider ownership and comprehensive 2024–2025 compensation and severance arrangements for senior executives and directors.
Spero Therapeutics, Inc. is soliciting proxies for its 2026 annual meeting to be held virtually at 9:00 a.m. ET on June 23, 2026. The Board asks stockholders to elect two directors; ratify PwC as auditor; approve executive compensation (advisory); approve an amendment to increase authorized common stock from 120,000,000 to 240,000,000 shares; and adopt the 2026 Stock Incentive Plan.
Holders of record as of April 24, 2026 may vote. The proxy materials, including the 2025 Annual Report on Form 10-K, will be delivered under the SEC notice-and-access process.
Spero Therapeutics reported a strong turnaround for 2025, moving from a net loss in 2024 to net income. Total revenues rose to $66.8M for the year ended December 31, 2025, up from $48.0M, driven mainly by collaboration revenue, including from its tebipenem HBr partnership with GSK.
Full-year research and development expense fell to $38.5M from $96.8M, while general and administrative costs declined modestly to $21.2M. Net income attributable to common shareholders was $8.6M for 2025 versus a $68.6M loss in 2024, and fourth quarter diluted EPS reached $0.53.
Cash, cash equivalents and marketable securities were $40.3M as of December 31, 2025, and Spero estimates this will fund operations into 2028. Operationally, the company completed the global phase 3 trial of tebipenem HBr in cUTI, resubmitted its NDA, and highlighted an FDA PDUFA decision date of June 18, 2026.
Spero Therapeutics’ annual report centers on its pivot to a single lead asset, tebipenem HBr, for complicated urinary tract infections. Tebipenem is partnered with GSK, has completed a pivotal Phase 3 trial that met its primary endpoint, and is under FDA review with a PDUFA date of June 18, 2026.
The company has ceased development of SPR206 and SPR720 to focus resources on supporting GSK and exploring new clinical‑stage assets. The GSK license provides milestone potential exceeding $300.0 million plus tiered royalties, but Spero remains dependent on tebipenem’s regulatory and commercial success and has not generated product sales.
Spero Therapeutics officer Esther Rajavelu reported automatic sales of Spero Therapeutics common stock to cover taxes from restricted stock unit (RSU) vesting. On February 6, 2026, she sold 37,101 shares and 50,816 shares, each at $2.36 per share, in sell-to-cover transactions that were not discretionary trades. After these tax-related sales, she directly beneficially owned 1,012,091 Spero Therapeutics shares.
Spero Therapeutics Chief Operating Officer Timothy Keutzer reported an automatic sale of common stock tied to tax obligations. On 02/06/2026, 18,652 shares of common stock were sold at $2.36 per share to cover tax withholding arising from restricted stock unit (RSU) vesting.
After this transaction, Keutzer beneficially owned 742,506 shares of Spero Therapeutics common stock in direct form. The filing explains that the sale was a mandatory "sell to cover" transaction to fund taxes and was not a discretionary trade by the executive.
Spero Therapeutics Chief Operating Officer Timothy Keutzer reported new equity awards and related tax sales of common stock. On February 2, 2026, he received 68,000 restricted stock units that vest in four equal annual installments beginning February 2, 2027, contingent on continued service. He also received a stock option for 137,000 shares at $2.23 per share, vesting 25% on February 2, 2027, with the rest vesting in 36 monthly installments.
To cover tax withholding from RSU vesting, Keutzer had automatic “sell to cover” transactions of 18,891 shares at $2.20, 24,224 shares at $2.14, and 3,471 shares at $2.24, which the filing states were not discretionary trades. After these transactions, he directly owned 761,158 shares of common stock and 137,000 stock options.
Spero Therapeutics officer Esther Rajavelu reported new equity awards and a small tax-related share sale. On February 2, 2026, she received 249,000 RSUs that vest in four equal annual installments starting February 2, 2027, and a stock option for 498,000 shares at an exercise price of $2.23, vesting 25% on February 2, 2027 and monthly thereafter.
To cover tax withholding from RSU vesting, 18,442 common shares were automatically sold at $2.20 in a non-discretionary “sell to cover” transaction. After these transactions, she directly held 1,100,008 common shares and 498,000 stock options.
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.