Welcome to our dedicated page for Spero Therapeuti SEC filings (Ticker: SPRO), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
The Spero Therapeutics, Inc. (Nasdaq: SPRO) SEC filings page on Stock Titan provides direct access to the company’s regulatory disclosures as filed with the U.S. Securities and Exchange Commission. Spero is a clinical-stage biopharmaceutical company headquartered in Cambridge, Massachusetts, focused on novel treatments for rare diseases and multi-drug resistant bacterial infections, and its filings offer detailed insight into this strategy.
Through periodic reports such as Forms 10-Q and 10-K, investors can review financial statements, including grant revenue, collaboration revenue related to its license agreement with GSK, research and development expenses for programs like tebipenem HBr and SPR720, general and administrative expenses, and net loss figures. These reports also discuss cash and cash equivalents and management’s views on the company’s funding runway, often referencing expected milestone payments from partners.
Current reports on Form 8-K, several of which are referenced in the input data, disclose material events such as quarterly operating results, the release of investor presentations, amendments to stock incentive plans, and outcomes of annual stockholder meetings. For example, Spero has filed 8-Ks to announce quarterly results, furnish press releases and investor decks, and report stockholder approval of increases to its 2017 Stock Incentive Plan share reserve.
Filings related to equity compensation and corporate governance detail inducement awards under the 2019 Inducement Equity Incentive Plan, amendments to long-term incentive plans, and advisory votes on executive compensation. Registration information confirms that Spero’s common stock is listed on The Nasdaq Global Select Market under the symbol SPRO.
On Stock Titan, these SEC documents are complemented by AI-powered summaries that highlight key points, such as changes in collaboration revenue with GSK, updates on the tebipenem HBr development program, and notable governance or compensation decisions. Users can quickly scan new 8-Ks, 10-Qs, and 10-Ks, then open the full filings for deeper review, making it easier to track Spero’s clinical progress, financial position, and corporate actions over time.
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.
Spero Therapeutics (SPRO) furnished materials related to its third-quarter update. The company provided a press release announcing results for the quarter ended September 30, 2025 and an investor presentation, both dated November 13, 2025.
The materials are furnished, not filed, which limits their legal exposure under the Exchange Act and Securities Act. The investor presentation is available on the company’s investor relations website.
Spero Therapeutics’ latest quarterly report shows a narrower loss and a sharper focus on its lead antibiotic candidate tebipenem HBr. For the quarter ended September 30, 2025, total revenue was $5.4 million, down from $13.5 million a year earlier as grant and collaboration revenue declined. Net loss improved to $7.4 million from $17.1 million, helped by lower research and development spending and collaboration milestone receipts.
At September 30, 2025, Spero held $48.6 million in cash and cash equivalents and stockholders’ equity of $26.5 million. Management believes this cash, combined with lower clinical spending after completing the pivotal PIVOT-PO trial, will fund operations for at least 12 months, but additional capital will be needed to carry products through approval and commercialization.
Strategically, Spero has ceased development of SPR206 and SPR720 and is now heavily dependent on tebipenem HBr and its license partnership with GSK. The PIVOT-PO Phase 3 trial in complicated urinary tract infections met its primary endpoint and was stopped early for efficacy, and GSK plans to file with the FDA in the fourth quarter of 2025. Key risks highlighted include continued operating losses, dependence on milestone and grant payments, manufacturing and regulatory uncertainties, stock price volatility, prior Nasdaq listing issues, and an ongoing SEC Wells Notice process related to the company’s 2022 tebipenem disclosures.
Spero Therapeutics (SPRO) reported an insider transaction on a Form 4. On 11/07/2025, a company executive sold 40,270 shares of common stock at $2.37 per share. The filing states this was a sell-to-cover to satisfy tax withholding upon the vesting of RSUs granted on November 13, 2023. Following the transaction, the executive beneficially owned 869,450 shares, held directly.