Investors who own more than 5% of a class must file a Schedule 13D or 13G. Every filing since 12/18/2024, newest first.
| Issuer | % of Class | Filed | |||
|---|---|---|---|---|---|
|
Mereo BioPharma Group plc
13G/A
Amendment 2
MREO · 589492107
|
0.6% |
8/14/2026
Event 6/30/2026
|
|||
| EcoR1 Capital, LLC | 0.6% | ||||
| Oleg Nodelman | 0.6% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0.6% | ||||
|
Alto Neuroscience, Inc.
13G
ANRO · 02157Q109
|
5.8% |
7/20/2026
Event 7/13/2026
|
|||
| EcoR1 Capital, LLC | 5.8% | ||||
| Oleg Nodelman | 5.8% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 5.3% | ||||
|
Fulcrum Therapeutics, Inc.
13G
FULC · 359616109
|
9.0% |
6/25/2026
Event 6/17/2026
|
|||
| EcoR1 Capital, LLC | 9.0% | ||||
| Oleg Nodelman | 9.0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 8.4% | ||||
|
Fulcrum Therapeutics, Inc.
13G
FULC · 359616109
|
9.0% |
6/25/2026
Event 6/17/2026
|
|||
| EcoR1 Capital, LLC | 9.0% | ||||
| Oleg Nodelman | 9.0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 8.4% | ||||
|
Eloxx Pharmaceuticals, Inc.
13G
ELOX · 29014R301
|
9.9% |
6/16/2026
Event 6/9/2026
|
|||
| EcoR1 Capital, LLC | 9.9% | ||||
| Oleg Nodelman | 9.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 9.3% | ||||
|
iBio, Inc.
13G/A
Amendment 1
IBIO · 451033708
|
4.6% |
5/15/2026
Event 3/31/2026
|
|||
| EcoR1 Capital, LLC | 4.6% | ||||
| Oleg Nodelman | 4.6% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 4.3% | ||||
|
Mereo BioPharma Group plc
13G/A
Amendment 1
MREO · 589492107
|
8.4% |
5/15/2026
Event 3/31/2026
|
|||
| EcoR1 Capital, LLC | 8.4% | ||||
| Oleg Nodelman | 8.4% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 7.8% | ||||
|
Xencor Inc
13G/A
Amendment 6
XNCR · 98401F105
|
2.9% |
5/15/2026
Event 3/31/2026
|
|||
| EcoR1 Capital, LLC | 2.9% | ||||
| Oleg Nodelman | 2.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 2.8% | ||||
|
Voyager Therapeutics, Inc.
13G/A
Amendment 7
VYGR · 92915B106
|
0% |
5/15/2026
Event 3/31/2026
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Atara Biotherapeutics, Inc.
13G/A
Amendment 3
ATRA · 046513206
|
17.4% |
5/7/2026
Event 5/7/2026
|
|||
| EcoR1 Capital, LLC | 17.4% | ||||
| Oleg Nodelman | 17.4% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 16.2% | ||||
|
First Tracks Biotherapeutics, Inc.
13G
TRAX · 337185102
|
9.1% |
4/22/2026
Event 4/20/2026
|
|||
| EcoR1 Capital, LLC | 9.1% | ||||
| Oleg Nodelman | 9.1% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 8.5% | ||||
|
uniQure N.V.
13G/A
Amendment 1
QURE · N90064101
|
0% |
2/17/2026
Event 12/31/2025
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Tango Therapeutics, Inc.
13G/A
Amendment 3
TNGX · 87583X109
|
0% |
2/17/2026
Event 12/31/2025
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Xencor Inc
13G/A
Amendment 5
XNCR · 98401F105
|
6.4% |
2/17/2026
Event 12/31/2025
|
|||
| EcoR1 Capital, LLC | 6.4% | ||||
| Oleg Nodelman | 6.4% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 6.0% | ||||
|
Voyager Therapeutics, Inc.
13G/A
Amendment 6
VYGR · 92915B106
|
6.8% |
2/17/2026
Event 12/31/2025
|
|||
| EcoR1 Capital, LLC | 6.8% | ||||
| Oleg Nodelman | 6.8% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 6.4% | ||||
|
Aktis Oncology, Inc.
13D
AKTS · 01021M104
|
9.1% |
1/20/2026
Event 1/12/2026
|
|||
| EcoR1 Capital, LLC | 9.1% | ||||
| Oleg Nodelman | 9.1% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 8.2% | ||||
|
Mereo BioPharma Group plc
13G
MREO · 589492107
|
9.4% |
1/9/2026
Event 1/2/2026
|
|||
| EcoR1 Capital, LLC | 9.4% | ||||
| Oleg Nodelman | 9.4% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 8.8% | ||||
|
iBio, Inc.
13G
IBIO · 451033708
|
9.9% |
12/17/2025
Event 12/10/2025
|
|||
| EcoR1 Capital, LLC | 9.9% | ||||
| Oleg Nodelman | 9.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 9.3% | ||||
|
Zymeworks Inc.
13D/A
Amendment 7
ZYME · 98985Y108
|
30.7% |
11/19/2025
Event 11/16/2025
|
|||
| EcoR1 Capital, LLC | 30.7% | ||||
| Oleg Nodelman | 30.7% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 28.8% | ||||
|
HilleVax, Inc.
13G/A
Amendment 1
HLVX · 43157M102
|
0% |
11/14/2025
Event 9/30/2025
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Tectonic Therapeutic, Inc.
13G/A
Amendment 2
TECX · 878972108
|
0% |
11/14/2025
Event 9/30/2025
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Atara Biotherapeutics, Inc.
13G/A
Amendment 2
ATRA · 046513206
|
9.9% |
11/14/2025
Event 9/30/2025
|
|||
| EcoR1 Capital, LLC | 9.9% | ||||
| Oleg Nodelman | 9.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 9.3% | ||||
|
Voyager Therapeutics, Inc.
13G/A
Amendment 5
VYGR · 92915B106
|
6.8% |
11/14/2025
Event 9/30/2025
|
|||
| EcoR1 Capital, LLC | 6.8% | ||||
| Oleg Nodelman | 6.8% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 6.4% | ||||
|
Neurogene Inc.
13G/A
Amendment 1
NGNE · 64135M105
|
9.9% |
11/14/2025
Event 9/30/2025
|
|||
| EcoR1 Capital, LLC | 9.9% | ||||
| Oleg Nodelman | 9.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 8.6% | ||||
|
Apellis Pharmaceuticals, Inc.
13G/A
Amendment 2
APLS · 03753U106
|
2.7% |
11/14/2025
Event 9/30/2025
|
|||
| EcoR1 Capital, LLC | 2.7% | ||||
| Oleg Nodelman | 2.7% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 2.5% | ||||
|
Adaptimmune Therapeutics PLC
13G/A
Amendment 2
ADAPY · 00653A107
|
4.2% |
8/19/2025
Event 8/15/2025
|
|||
| EcoR1 Capital, LLC | 4.2% | ||||
| Oleg Nodelman | 4.2% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 4.0% | ||||
|
Kura Oncology, Inc.
13G/A
Amendment 3
KURA · 50127T109
|
4.8% |
8/14/2025
Event 6/30/2025
|
|||
| EcoR1 Capital, LLC | 4.8% | ||||
| Oleg Nodelman | 4.8% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 4.5% | ||||
|
ORIC Pharmaceuticals, Inc.
13G
ORIC · 68622P109
|
6.9% |
8/5/2025
Event 7/29/2025
|
|||
| EcoR1 Capital, LLC | 6.9% | ||||
| Oleg Nodelman | 6.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 6.5% | ||||
|
Galapagos NV
13D/A
Amendment 3
LKFT · 36315X101
|
13.2% |
7/28/2025
Event 7/24/2025
|
|||
| EcoR1 Capital, LLC | 13.2% | ||||
| Oleg Nodelman | 13.2% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 12.4% | ||||
| EcoR1 Capital Fund, L.P. | 0.8% | ||||
|
HilleVax, Inc.
13G
HLVX · 43157M102
|
5.8% |
7/24/2025
Event 7/17/2025
|
|||
| EcoR1 Capital, LLC | 5.8% | ||||
| Oleg Nodelman | 5.8% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 5.4% | ||||
|
Zymeworks Inc.
13D
ZYME · 98985Y108
|
30.7% |
6/27/2025
Event 6/26/2025
|
|||
| EcoR1 Capital, LLC | 30.7% | ||||
| Oleg Nodelman | 30.7% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 28.8% | ||||
|
Prothena Corp Public Ltd Co
13D/A
Amendment 6
PRTA · G72800108
|
0% |
5/29/2025
Event 5/27/2025
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Galapagos NV
13D/A
Amendment 2
LKFT · 36315X101
|
11.8% |
5/19/2025
Event 5/15/2025
|
|||
| EcoR1 Capital, LLC | 11.8% | ||||
| Oleg Nodelman | 11.8% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 11.1% | ||||
| EcoR1 Capital Fund, L.P. | 0.7% | ||||
|
iTeos Therapeutics, Inc.
13D
ITOS · 46565G104
|
27.9% |
5/16/2025
Event 5/15/2025
|
|||
| EcoR1 Capital, LLC | 27.9% | ||||
| Oleg Nodelman | 27.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 26.2% | ||||
|
Third Harmonic Bio, Inc.
13G/A
Amendment 2
THRD · 88427A107
|
0% |
5/15/2025
Event 3/31/2025
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Tectonic Therapeutic, Inc.
13G/A
Amendment 1
TECX · 878972108
|
5.0% |
5/15/2025
Event 3/31/2025
|
|||
| EcoR1 Capital, LLC | 5.0% | ||||
| Oleg Nodelman | 5.0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 4.7% | ||||
|
TScan Therapeutics, Inc.
13G/A
Amendment 1
TCRX · 89854M101
|
1.3% |
5/15/2025
Event 3/31/2025
|
|||
| EcoR1 Capital, LLC | 1.3% | ||||
| Oleg Nodelman | 1.3% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 1.2% | ||||
|
Mersana Therapeutics, Inc.
13G/A
Amendment 2
MRSN · 59045L106
|
0% |
5/15/2025
Event 3/31/2025
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Kalaris Therapeutics, Inc.
13G/A
Amendment 2
KLRS · 482929106
|
1.1% |
5/15/2025
Event 3/31/2025
|
|||
| EcoR1 Capital, LLC | 1.1% | ||||
| Oleg Nodelman | 1.1% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 1.0% | ||||
|
Immunome Inc.
13G/A
Amendment 1
IMNM · 45257U108
|
4.7% |
5/15/2025
Event 3/31/2025
|
|||
| EcoR1 Capital, LLC | 4.7% | ||||
| Oleg Nodelman | 4.7% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 4.4% | ||||
|
Arvinas, Inc.
13G/A
Amendment 3
ARVN · 04335A105
|
0% |
5/15/2025
Event 3/31/2025
|
|||
| EcoR1 Capital, LLC | 0% | ||||
| Oleg Nodelman | 0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 0% | ||||
|
Aligos Therapeutics, Inc.
13G/A
Amendment 4
ALGS · 01626L204
|
3.9% |
5/15/2025
Event 3/31/2025
|
|||
| EcoR1 Capital, LLC | 3.9% | ||||
| Oleg Nodelman | 3.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 3.7% | ||||
|
iTeos Therapeutics, Inc.
13G/A
Amendment 1
ITOS · 46565G104
|
14.9% |
5/13/2025
Event 5/13/2025
|
|||
| EcoR1 Capital, LLC | 14.9% | ||||
| Oleg Nodelman | 14.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 14.0% | ||||
|
iTeos Therapeutics, Inc.
13G
ITOS · 46565G104
|
6.9% |
5/8/2025
Event 5/1/2025
|
|||
| EcoR1 Capital, LLC | 6.9% | ||||
| Oleg Nodelman | 6.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 6.5% | ||||
|
Prothena Corp Public Ltd Co
13D/A
Amendment 5
PRTA · G72800108
|
9.9% |
5/6/2025
Event 5/2/2025
|
|||
| EcoR1 Capital, LLC | 9.9% | ||||
| Oleg Nodelman | 9.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 9.2% | ||||
|
Zymeworks Inc.
13D/A
Amendment 5
ZYME · 98985Y108
|
25.4% |
4/8/2025
Event 4/4/2025
|
|||
| EcoR1 Capital, LLC | 25.4% | ||||
| Oleg Nodelman | 25.4% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 23.9% | ||||
|
Zymeworks Inc.
13D/A
Amendment 4
ZYME · 98985Y108
|
24.2% |
3/17/2025
Event 3/13/2025
|
|||
| EcoR1 Capital, LLC | 24.2% | ||||
| Oleg Nodelman | 24.2% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 22.7% | ||||
|
Zymeworks Inc.
13D/A
Amendment 3
ZYME · 98985Y108
|
22.8% |
2/18/2025
Event 2/17/2025
|
|||
| EcoR1 Capital, LLC | 22.8% | ||||
| Oleg Nodelman | 22.8% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 21.4% | ||||
|
Allovir, Inc.
13G/A
Amendment 1
ALVR · 019818202
|
8.1% |
2/14/2025
Event 12/31/2024
|
|||
| EcoR1 Capital, LLC | 8.1% | ||||
| Oleg Nodelman | 8.1% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 7.7% | ||||
|
Eton Pharmaceuticals, Inc.
13G/A
Amendment 1
ETON · 29772L108
|
7.7% |
2/14/2025
Event 12/31/2024
|
|||
| EcoR1 Capital, LLC | 7.7% | ||||
| Oleg Nodelman | 7.7% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 7.2% | ||||
|
Atea Pharmaceuticals, Inc.
13G/A
Amendment 4
AVIR · 04683R106
|
4.0% |
2/14/2025
Event 12/31/2024
|
|||
| EcoR1 Capital, LLC | 4.0% | ||||
| Oleg Nodelman | 4.0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 3.7% | ||||
|
Tango Therapeutics, Inc.
13G/A
Amendment 2
TNGX · 87583X109
|
9.9% |
2/14/2025
Event 12/31/2024
|
|||
| EcoR1 Capital, LLC | 9.9% | ||||
| Oleg Nodelman | 9.9% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 9.3% | ||||
|
HOOKIPA Pharma Inc.
13G/A
Amendment 2
HOOK · 43906K209
|
4.0% |
2/14/2025
Event 12/31/2024
|
|||
| EcoR1 Capital, LLC | 4.0% | ||||
| Oleg Nodelman | 4.0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 3.8% | ||||
|
Aadi Bioscience, Inc.
13G/A
Amendment 1
WHWK · 00032Q104
|
1.4% |
2/14/2025
Event 12/31/2024
|
|||
| EcoR1 Capital, LLC | 1.4% | ||||
| Oleg Nodelman | 1.4% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 1.3% | ||||
|
Zymeworks Inc.
13D/A
Amendment 2
ZYME · 98985Y108
|
22.4% |
1/13/2025
Event 1/10/2025
|
|||
| EcoR1 Capital, LLC | 22.4% | ||||
| Oleg Nodelman | 22.4% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 21.0% | ||||
|
Prothena Corporation plc
13D/A
Amendment 4
PRTA · G72800108
|
21.5% |
1/3/2025
Event 12/31/2024
|
|||
| EcoR1 Capital, LLC | 21.5% | ||||
| Oleg Nodelman | 21.5% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 20.2% | ||||
|
Zymeworks Inc.
13D/A
Amendment 1
ZYME · 98985Y108
|
21.3% |
12/23/2024
Event 12/19/2024
|
|||
| EcoR1 Capital, LLC | 21.3% | ||||
| Oleg Nodelman | 21.3% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 20.1% | ||||
|
Mersana Therapeutics, Inc.
13G/A
Amendment 1
MRSN · 59045L106
|
10.0% |
12/23/2024
Event 12/19/2024
|
|||
| EcoR1 Capital, LLC | 10.0% | ||||
| Oleg Nodelman | 10.0% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 9.4% | ||||
|
uniQure N.V.
13G
QURE · N90064101
|
7.5% |
12/17/2024
Event 12/10/2024
|
|||
| EcoR1 Capital, LLC | 7.5% | ||||
| Oleg Nodelman | 7.5% | ||||
| EcoR1 Capital Fund Qualified, L.P. | 7.0% | ||||