Quantum-Si Inc (QSI) Institutional Ownership

Ownership Summary

Recent 13F filings as of December 2025 show that 128 institutional investors hold a position in Quantum-Si Inc (NASDAQ:QSI).

• The collective stake of institutional investors in Quantum-Si moved to 38.5% in December 2025, a shift up from the 37.0% reported for September 2025.
• In percentage terms, this reflects as a holdings change of 6.57% quarter on quarter, and an increase of 11.30% year over year.
• During the quarter, 63 institutions bought more Quantum-Si shares, 37 sold shares, and 28 of the 128 total investors held their position steady.
• The total number of shares held by institutions in Quantum-Si increased to 67.07Mn as of December 2025, a net change of up by 4.14Mn shares quarter on quarter, and up 13.48Mn shares year over year.
• BlackRock, Inc.'s holding of 13.05Mn shares as of December 31, 2025 makes it the primary institutional investor in Quantum-Si, owning 7.49% of the stock.
• Among the most significant buyers of Quantum-Si during December 2025 were CITADEL ADVISORS LLC (2.27Mn), BlackRock, Inc. (1.73Mn), UBS Group AG (944.65K), VANGUARD GROUP INC (892.51K), TWO SIGMA INVESTMENTS, LP (868.33K).
• Leading sellers of Quantum-Si stock in December 2025 included MILLENNIUM MANAGEMENT LLC (2.48Mn), ARK Investment Management LLC (602.47K), ROYAL BANK OF CANADA (527.83K), Amova Asset Management Americas, Inc. (526.78K), Sumitomo Mitsui Trust Group, Inc. (526.78K).
• The top 10 institutional holders of Quantum-Si for the quarter ending December 2025 included BlackRock, Inc. (13.05Mn), VANGUARD GROUP INC (9.61Mn), ARK Investment Management LLC (7.02Mn), Amova Asset Management Americas, Inc. (4.69Mn), Sumitomo Mitsui Trust Group, Inc. (4.69Mn), GEODE CAPITAL MANAGEMENT, LLC (4.11Mn), STATE STREET CORP (3.56Mn), CITADEL ADVISORS LLC (2.68Mn), SUSQUEHANNA INTERNATIONAL GROUP, LLP (2.33Mn), NORTHERN TRUST CORP (2.21Mn).