Security key
59045L106
Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share (MRSN)
CUSIP: 59045L106
Q4 2024 13F Holders as of 31 Dec 2024
- Security type / class
- Equity / Common Stock, par value $0.0001 per share
- Total 13F shares
- 104,303,178
- Total 13F value
- $149,151,003
- Share change
- -16,105,576
- Put/Call ratio
- 587%
- SEC-reported price per share
- $1.43
- Number of holders
- 129
- Value change
- -$24,954,008
- Number of buys
- 52
- Number of sells
- 53
- Shares outstanding
- 4,992,318
Holder snapshot
7 signals
Open additional details 1 more signal available
Security identity
Names, identifiers, and filing context for this profile.
1 source field
Report period
Q4 2024
Institutions
129
Top holders
10
MRSN full security history
Ownership snapshot
Full 13F holder table
Newer quarter: Q4 2025
Mersana Therapeutics, Inc. SEC filings
Mersana Therapeutics, Inc. company facts
Broader feeds
Reporting periods
Holder history for CUSIP 59045L106
Recent filing periods:
Ownership snapshot
Top reported holders of MRSN - Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
Nextech Crossover I GP S....
Disclosed value leader
EcoR1 Capital, LLC
Comparable rows
15/15
Latest evidence
20 Dec 2024
13D/G
13F
3/4/5
Lead comparable stake: 10%
13D/G row: Nextech Crossover I GP S.a r.l.
Showing 1-6 of 15 holder rows.
Quick read
Nextech Crossover I GP S.a r.l. leads the comparable SEC ownership view at 10%.
15 of 15 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens Nextech Crossover I GP S.a r.l.'s linked filing trail.
Comparable ownership
Top 5
Nextech Crossover I GP S.a r.l.
10%
EcoR1 Capital, LLC
388%
Nextech Invest Ltd.
242%
Venrock Adviser, LLC
227%
Bain Capital Life Sciences Invest...
174%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-6 of 15 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Nextech Crossover I GP S.a r.l. |
13D/G
|
10%
|
$4,344,209
12,067,246 shares
|
$0 | 20 Dec 2024 |
| EcoR1 Capital, LLC |
13F
3/4/5
Company · 10%+ Owner
|
388%
|
$36,599,260
19,364,688 shares
|
— | 30 Sep 2024 |
| Nextech Invest Ltd. |
13F
Company
|
242%
|
$22,807,095
12,067,246 shares
|
— | 30 Sep 2024 |
| Venrock Adviser, LLC |
13F
Company
|
227%
|
$21,409,920
11,328,000 shares
|
— | 30 Sep 2024 |
| Bain Capital Life Sciences Investors, LLC |
13F
Company
|
174%
|
$16,374,342
8,663,673 shares
|
— | 30 Sep 2024 |
| BlackRock, Inc. |
13F
Company
|
173%
|
$16,295,319
8,621,861 shares
|
— | 30 Sep 2024 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
13F holder rows
Institutional holders as of Q4 2024
Investor-level positions for this CUSIP, loaded as an interactive table.
Institutions
129
Shares
104,303,178
Rows available
129
| Investor | Option | Weight % | Change % | SEC-reported value | * Price | Shares | Share Change | Activity | Report Period |
|---|
* SEC-reported price is the security price as of the portfolio date and can indicate the last known price at which the security was still held. The marker flags a reported price that did not pass the local price check.
Compare Q4 2024 vs Q4 2025 Across Filers
Q4 2025 holders
3
Q4 2024 holders
129
Holder diff
126
| Investor | Q4 2025 Shares | Q4 2024 Shares | Share Diff | Share Chg % | Q4 2025 value | Q4 2024 value | Value change | Value Chg % |
|---|
Trend: ostatnie 8 kwartałów (+ wybrane okresy porównania).
Quarterly Holders Trend
Quarterly Value Trend
Quarterly Shares Trend