Ph.D. Jonathan M. Rothberg - 09 Sep 2025 SCHEDULE 13D/A Report for Quantum-Si Inc Class A common stock, par value $0.0001 per share, Class B common stock, par value $0.0001 per share (QSI)

Filing Manager
Ph.D. Jonathan M. Rothberg
Reporting Manager
ROTHBERG JONATHAN M.
Security
Quantum-Si Inc Class A common stock, par value $0.0001 per share, Class B common stock, par value $0.0001 per share
Symbol
QSI
Shares outstanding
19,937,500 shares
Disclosed Ownership
19,937,500 shares
Ownership
100%
Form type
SCHEDULE 13D/A
Filing time
11 Sep 2025, 17:04:02 UTC
Date of event
09 Sep 2025
Previous filing
31 Dec 2024
SEC
View on sec.gov

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Quoteable Key Fact

"Ph.D. Jonathan M. Rothberg disclosed 100% ownership in Quantum-Si Inc Class A common stock, par value $0.0001 per share, Class B common stock, par value $0.0001 per share (QSI) on 09 Sep 2025."

Quick Takeaways

  • Ph.D. Jonathan M. Rothberg filed SCHEDULE 13D/A for Quantum-Si Inc Class A common stock, par value $0.0001 per share, Class B common stock, par value $0.0001 per share (QSI).
  • Disclosed ownership: 100%.
  • Date of event: 09 Sep 2025.

What Changed

  • Previous schedule filing date: 31 Dec 2024.
  • Current filing was accepted on 11 Sep 2025, 17:04.

Why This Matters

  • This page explains what this Schedule 13D/13G filing tells you before manager-level rows.
  • You can verify ownership claims directly against the original SEC filing.

Official SEC Source

Backed by Schedule 13D/13G

Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.

See Original Filing

Reporting Managers (6)

Name Ownership Shares Owned sole voting power shared voting power Signature Title CIK
ROTHBERG JONATHAN M 7.8% 14,276,415 12,085,926 2,190,489 /s/ Jonathan M. Rothberg Jonathan M. Rothberg, Ph.D. 0001076352
ROTHBERG JONATHAN M. 100% 19,937,500 19,937,500 0 /s/ Jonathan M. Rothberg Jonathan M. Rothberg, Ph.D.
23rd Century Capital LLC 1% 1,917,067 1,917,067 /s/ Jonathan M. Rothberg Jonathan M. Rothberg, Ph.D., Member
2012 JMR Trust Common, LLC 0% /s/ Jonathan M. Rothberg Jonathan M. Rothberg, Ph.D., Manager
4C Holdings I, LLC 90% 17,943,750 17,943,750 /s/ Jonathan M. Rothberg Jonathan M. Rothberg, Ph.D., Manager
4C Holdings V, LLC 10% 1,993,750 1,993,750 /s/ Jonathan M. Rothberg Jonathan M. Rothberg, Ph.D., Manager

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