Upstream Bio, Inc. (UPB) Institutional Ownership

Ownership Summary

Recent 13F filings as of September 2025 show that 96 institutional investors hold a position in Upstream Bio, Inc. (NASDAQ:UPB).

• These investors collectively held 83.0% of the company's total shares outstanding in September 2025, down from 89.9% in June 2025.
• Quarterly data indicates a -2.61% shift in institutional share volume, and the annual owner count reflects an unavailable change.
• Of these 96 institutional investors, 58 increased their holdings in Upstream Bio, while 27 of them reduced positions, and 11 investors maintained their exposure.
• Collectively, institutional investors decreased their stake in Upstream Bio to 44.75Mn shares as of September 2025, a change that is down by 1.20Mn shares quarter on quarter and down N/A shares year over year.
• FMR LLC's holding of 8.09Mn shares as of September 30, 2025 makes it the primary institutional investor in Upstream Bio, owning 15.00% of the stock.
• Among the most significant buyers of Upstream Bio during September 2025 were STATE STREET CORP (633.21K), MARSHALL WACE, LLP (577.47K), Integral Health Asset Management, LLC (575.00K), BlackRock, Inc. (507.20K), VANGUARD GROUP INC (271.72K).
• Leading sellers of Upstream Bio stock in September 2025 included Altshuler Shaham Ltd (1.98Mn), VR Adviser, LLC (1.13Mn), TCG Crossover Management, LLC (684.66K), Omega Fund Management, LLC (680.00K), Samsara BioCapital, LLC (481.08K).
• The top 10 institutional holders of Upstream Bio for the quarter ending September 2025 included FMR LLC (8.09Mn), ORBIMED ADVISORS LLC (5.69Mn), Decheng Capital LLC (3.29Mn), BlackRock, Inc. (2.60Mn), Enavate Sciences GP, LLC (2.46Mn), VANGUARD GROUP INC (2.44Mn), Bain Capital Life Sciences Investors, LLC (2.44Mn), TCG Crossover Management, LLC (2.12Mn), Altshuler Shaham Ltd (1.42Mn), Omega Fund Management, LLC (1.36Mn).