Spero Therapeutics, Inc. Common Stock (SPRO)

About Spero Therapeutics, Inc. Common Stock

Spero Therapeutics Inc is a clinical-stage biopharmaceutical firm. It focuses on identifying, developing, and commercializing novel treatments for MDR (Multi-drug-resistant) bacterial infections and rare diseases. The company's product candidate, tebipenem pivoxil hydrobromide or tebipenem HBr, is designed to be an oral carbapenem-class antibiotic for use in adults to treat MDR Gram-negative infections. It is also developing SPR720, a novel oral antibiotic designed for the treatment of a rare, orphan disease caused by pulmonary non-tuberculous mycobacterial infections, or NTM disease. It is also focused on SPR206, a next-generation polymyxin investigational product candidate being developed as an IV-administered medicine to treat MDR Gram-negative infections in the hospital.

Institutional ownership

In 13F filings for the quarter ended June 30, 2026, 59 institutions reported holding SPRO, with 21.5 million shares worth $47.5 million in aggregate. The largest reported holder was Gsk, with 9.2 million shares worth $20.3 million. Of the 5 largest holders listed below, 1 added shares, 1 reduced its position and 3 held their positions unchanged during the quarter.

Form 13F is a quarterly report that institutional investment managers with at least $100 million in qualifying securities file with the SEC. It lists long positions as of the last day of the quarter and is due within 45 days of quarter end, so these holdings describe that date rather than today.

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