Spero Therapeutics, Inc. (SPRO) Institutional Ownership

Ownership Summary

Spero Therapeutics, Inc. (NASDAQ:SPRO) has 56 institutional investors with active 13F positions as of December 2025.

• These investors held 37.8% of outstanding shares in December 2025, up from 20.0% in September 2025.
• Their total shares held in SPRO increased 93.33% from the prior quarter, while the number of investors in Spero Therapeutics increased 12.0% year over year.
• During the quarter, 32 of these 56 funds increased positions in SPRO, 11 reduced exposure, and 13 held steady.
• The aggregate institutional position in Spero Therapeutics amounted to 21.27Mn shares as of December 2025, up by 10.27Mn shares quarter on quarter, and up 5.2Mn shares year over year.
• As of December 31, 2025, the biggest holder of Spero Therapeutics is GSK plc at 9.19Mn shares, representing 16.33% of shares outstanding.
• The most significant purchases of SPRO for the quarter ending December 2025 came from GSK plc (9.19Mn), CITADEL ADVISORS LLC (397.86K), TWO SIGMA INVESTMENTS, LP (323.17K), SUSQUEHANNA INTERNATIONAL GROUP, LLP (293.7K), TWO SIGMA ADVISERS, LP (216.6K).
• The largest sales of SPRO for the quarter ending December 2025 came from Anson Funds Management LP (978.51K), RENAISSANCE TECHNOLOGIES LLC (173.24K), Informed Momentum Co LLC (64.36K), Morgan Stanley (43.06K), Assenagon Asset Management S.A. (18.36K).
• Business Quant data shows the 10 biggest positions in Spero Therapeutics as of December 2025 are held by GSK plc (9.19Mn), Pfizer Inc (2.36Mn), VANGUARD GROUP INC (2.08Mn), RENAISSANCE TECHNOLOGIES LLC (1.28Mn), Alphabet Inc. (889.98K), Anson Funds Management LP (625.06K), GEODE CAPITAL MANAGEMENT, LLC (529.2K), BlackRock, Inc. (433.62K), CITADEL ADVISORS LLC (397.86K), TWO SIGMA INVESTMENTS, LP (372.57K).