683 Capital Management, LLC - 31 Dec 2025 SCHEDULE 13G/A Report for Mersana Therapeutics, Inc. Common Stock, par value $0.0001 per share (MRSN)

Filing Manager
683 Capital Management, LLC
Reporting Manager
683 Capital Management, LLC
Security
Mersana Therapeutics, Inc. Common Stock, par value $0.0001 per share
Symbol
MRSN
Shares outstanding
4,996,999 shares
Disclosed Ownership
351,289 shares
Ownership
7%
Form type
SCHEDULE 13G/A
Filing time
17 Feb 2026, 10:09:02 UTC
Date of event
31 Dec 2025
Previous filing
24 Nov 2025
SEC
View on sec.gov

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Quoteable Key Fact

"683 Capital Management, LLC disclosed 7% ownership in Mersana Therapeutics, Inc. Common Stock, par value $0.0001 per share (MRSN) on 31 Dec 2025."

Quick Takeaways

  • 683 Capital Management, LLC filed SCHEDULE 13G/A for Mersana Therapeutics, Inc. Common Stock, par value $0.0001 per share (MRSN).
  • Disclosed ownership: 7%.
  • Date of event: 31 Dec 2025.

What Changed

  • Previous schedule filing date: 24 Nov 2025.
  • Current filing was accepted on 17 Feb 2026, 10:09.

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 (3)

Name Ownership Shares Owned sole voting power shared voting power Signature Title CIK
683 Capital Management, LLC 7% 351,289 0 351,289 Ari Zweiman Managing Member
683 Capital Partners, LP 7% 351,289 0 351,289 Ari Zweiman Authorized Person
Ari Zweiman 7% 351,289 0 351,289 Ari Zweiman Self

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