EcoR1 Capital, LLC — SEC Form 4 filings
SEC reporting owner CIK 1587114. 26 Form 4 filings on record with FilingPulse; latest filed 2026-05-11.
Transaction summary — filings shown
Covers all 26 filings on record, filed 2024-08-16 to 2026-05-11. Counts and totals are arithmetic on values as filed — descriptive data, not a recommendation.
- Open-market purchases (code P, non-derivative): 45 legs across 19 filings — 12,494,112 shares, $152,565,487 total (shares × price as filed).
- Open-market sales (code S, non-derivative): 10 legs across 4 filings — 77,737,797 shares, $131,165,776 total (shares × price as filed).
- Other reported legs (grants, option exercises, tax withholding, gifts, derivative-security transactions, …): 16.
- Largest priced transaction: sale of 4,705,575 shares @ $13.81 ($64,999,990) in First Tracks Biotherapeutics, Inc., filed 2026-04-22.
By issuer — same filings
Open-market purchase/sale legs on non-derivative securities, grouped by issuer. Role is as filed on the newest filing for that issuer. Dollar totals cover priced legs only (shares × price as filed). Ordered by priced transaction value, largest first.
| Issuer | Role (as filed) | Filings | Purchases (P) | Sales (S) | Other legs |
|---|---|---|---|---|---|
| First Tracks Biotherapeutics, Inc. (TRAX) | 10% owner | 1 | — | 1 leg · 4,705,575 sh · $64,999,990 | — |
| Zymeworks Inc. (ZYME) | Director, 10% owner | 16 | 36 legs · 4,446,435 sh · $58,036,053 | — | 4 |
| PROTHENA CORP PUBLIC LTD CO (PRTA) | 10% owner | 1 | — | 3 legs · 6,279,684 sh · $50,839,807 | — |
| Aktis Oncology, Inc. (AKTS) | Director | 1 | 2 legs · 2,222,222 sh · $39,999,996 | — | 10 |
| iTeos Therapeutics, Inc. (ITOS) | 10% owner | 1 | 2 legs · 4,958,978 sh · $38,685,562 | — | — |
| ANAPTYSBIO, INC (ANAB) | Director, 10% owner | 2 | 4 legs · 359,070 sh · $11,099,620 | — | — |
| Tango Therapeutics, Inc. (TNGX) | 10% owner | 1 | — | 3 legs · 2,700,000 sh · $8,435,743 | — |
| Adaptimmune Therapeutics PLC (ADAP) | 10% owner | 1 | — | 3 legs · 64,052,538 sh · $6,890,236 | — |
| Atara Biotherapeutics, Inc. (ATRA) | 10% owner | 1 | 1 leg · 507,407 sh · $4,744,255 | — | — |
| Mersana Therapeutics, Inc. (MRSN) | 10% owner | 1 | — | — | 2 |
Form 4 filings — EcoR1 Capital, LLC
| Filed | Form | Issuer | Reported transactions | Source |
|---|---|---|---|---|
| 2026-05-11 | 4 | Atara Biotherapeutics, Inc. (ATRA) | Purchase (P): 507,407 @ $9.35 | EDGAR |
| 2026-04-22 | 4 | First Tracks Biotherapeutics, Inc. (TRAX) | Sale (S): 4,705,575 @ $13.81 | EDGAR |
| 2026-01-12 | 4 | Aktis Oncology, Inc. (AKTS) jointly with NODELMAN OLEG | Conversion (C): 2,270,879 · Conversion (C): 202,862 · Conversion (C): 128,506 · Purchase (P): 2,077,779 @ $18 · Purchase (P): 144,443 @ $18 · Conversion (C): 9,913,810 (derivative) · +6 more | EDGAR |
| 2025-07-30 | 4 | Adaptimmune Therapeutics PLC (ADAP) | Sale (S): 33,931,740 @ $0.11 · Sale (S): 2,687,460 @ $0.10 · Sale (S): 27,433,338 @ $0.10 | EDGAR |
| 2025-06-27 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Option exercise/expiry (X): 5,086,480 @ $0.00 · Tax withholding (F): 41 @ $12.71 · Option exercise/expiry (X): 5,086,521 (derivative) @ $0 | EDGAR |
| 2025-05-19 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Purchase (P): 49,502 @ $11.43 · Purchase (P): 5,919 @ $11.78 | EDGAR |
| 2025-05-16 | 4 | iTeos Therapeutics, Inc. (ITOS) | Purchase (P): 1,658,978 @ $7.41 · Purchase (P): 3,300,000 @ $8 | EDGAR |
| 2025-05-06 | 4 | PROTHENA CORP PUBLIC LTD CO (PRTA) | Sale (S): 3,317,938 @ $8.36 · Sale (S): 977,693 @ $8.11 · Sale (S): 1,984,053 @ $7.64 | EDGAR |
| 2025-04-18 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Purchase (P): 73,953 @ $11.16 · Purchase (P): 54,760 @ $11.52 | EDGAR |
| 2025-04-07 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Purchase (P): 120,770 @ $11.84 · Purchase (P): 196,438 @ $11.17 | EDGAR |
| 2025-04-02 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Purchase (P): 4,397 @ $11.75 · Purchase (P): 48,658 @ $11.60 · Purchase (P): 74,360 @ $11.85 | EDGAR |
| 2025-03-27 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Purchase (P): 53,501 @ $12.91 · Purchase (P): 43,848 @ $12.24 | EDGAR |
| 2025-03-24 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Purchase (P): 73,476 @ $12.93 · Purchase (P): 31,033 @ $12.78 · Purchase (P): 22,689 @ $13.08 | EDGAR |
| 2025-03-19 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Purchase (P): 56,277 @ $12.23 · Purchase (P): 113,880 @ $12.65 · Purchase (P): 58,306 @ $12.64 | EDGAR |
| 2025-03-13 | 4 | Zymeworks Inc. (ZYME) jointly with NODELMAN OLEG | Purchase (P): 320,690 @ $11.49 · Purchase (P): 292,934 @ $12.25 · Purchase (P): 468,356 @ $12.48 | EDGAR |
| 2025-01-21 | 4 | Zymeworks Inc. (ZYME) | Purchase (P): 121,681 @ $13.88 · Purchase (P): 19,748 @ $13.87 | EDGAR |
| 2025-01-15 | 4 | Zymeworks Inc. (ZYME) | Purchase (P): 74,125 @ $13.39 · Purchase (P): 54,500 @ $13.56 · Purchase (P): 39,029 @ $14.01 | EDGAR |
| 2025-01-10 | 4 | Zymeworks Inc. (ZYME) | Purchase (P): 21,021 @ $14.07 · Purchase (P): 204,098 @ $13.13 | EDGAR |
| 2025-01-02 | 4 | ANAPTYSBIO, INC (ANAB) jointly with NODELMAN OLEG | Purchase (P): 65,184 @ $12.92 · Purchase (P): 13,268 @ $12.93 · Purchase (P): 6,646 @ $12.95 | EDGAR |
| 2025-01-02 | 4 | Zymeworks Inc. (ZYME) | Purchase (P): 58,988 @ $14.47 · Purchase (P): 146,501 @ $14.57 · Purchase (P): 157,880 @ $14.78 | EDGAR |
| 2024-12-27 | 4 | Zymeworks Inc. (ZYME) | Purchase (P): 11,958 @ $14.12 · Purchase (P): 16,692 @ $14.38 · Purchase (P): 101,659 @ $14.49 | EDGAR |
| 2024-12-26 | 4/A | Zymeworks Inc. (ZYME) | Purchase (P): 298,818 @ $13.53 · Purchase (P): 704,488 @ $14.08 · Purchase (P): 251,502 @ $14.25 | EDGAR |
| 2024-12-23 | 4 | Mersana Therapeutics, Inc. (MRSN) | Other (J): 8,036,688 · Other (J): 8,036,688 (derivative) | EDGAR |
| 2024-12-23 | 4 | Zymeworks Inc. (ZYME) | Purchase (P): 5,086,521 (derivative) @ $9.83 | EDGAR |
| 2024-11-08 | 4 | Tango Therapeutics, Inc. (TNGX) | Sale (S): 1,494,558 @ $3.28 · Sale (S): 62,318 @ $3.29 · Sale (S): 1,143,124 @ $2.92 | EDGAR |
| 2024-08-16 | 4 | ANAPTYSBIO, INC (ANAB) | Purchase (P): 273,972 @ $36.50 | EDGAR |
FilingPulse's Form 4 archive currently extends back to 2024-01-11 and is expanding backward through EDGAR history — earlier filings by this insider may not be indexed yet. Names and roles are shown as filed.
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