EcoR1 Capital, LLC

Director · Ten-percent owner · ATRA, TRAX, AKTS, ZYME, ITOS, PRTA …

As of 2026-09-16, EcoR1 Capital, LLC has 86 Form 4 transactions on record across 8 companies — 34 in the trailing 12 months.

Everything this person has disclosed to the SEC on Form 4 — across every company they file for — reconstructed from the public record. A filing history, not a tip sheet.

Pattern in the record: open-market purchases filed in May in multiple years since 2025 — a recurring calendar cadence, more consistent with scheduled activity than a one-off decision.

Reconstructed holdings

Direct: $0Indirect: $955.3M$955.3Mas of 2026-09-16
  • Direct $0
  • Indirect $955.3M
ANABindirect7,880,094 sh$428.0M
MRSNindirect8,036,688 sh$233.7M
TRAXindirect3,174,519 sh$123.8M
ITOSindirect10,688,978 sh$108.5M
PRTAindirect5,304,596 sh$43.7M
ATRAindirect1,552,000 sh$15.7M
AKTSindirect86,222 sh$2.0M

Reconstructed from this person's own Form 4 filings — the total each filing reported owning afterward, priced at the close on the as-of date shown. A filed position can lag the real one.

Direct and indirect holdings (e.g. through a trust or fund) are tagged separately, as filed.

Trades by company

ZYME · 37 trades
2025-06-26: Withheld for tax, 41 sh ($521)2025-06-26: Exercise, 5,086,480 sh ($509)2025-06-26: Exercise, 5,086,521 sh ($0)2025-05-19: Purchase, 5,919 sh ($70K)2025-05-15: Purchase, 49,502 sh ($566K)2025-04-17: Purchase, 54,760 sh ($631K)2025-04-16: Purchase, 73,953 sh ($826K)2025-04-04: Purchase, 196,438 sh ($2.2M)2025-04-03: Purchase, 120,770 sh ($1.4M)2025-04-02: Purchase, 74,360 sh ($881K)2025-04-01: Purchase, 48,658 sh ($565K)2025-03-31: Purchase, 4,397 sh ($52K)2025-03-26: Purchase, 43,848 sh ($537K)2025-03-25: Purchase, 53,501 sh ($690K)2025-03-24: Purchase, 22,689 sh ($297K)2025-03-21: Purchase, 31,033 sh ($397K)2025-03-20: Purchase, 73,476 sh ($950K)2025-03-19: Purchase, 58,306 sh ($737K)2025-03-18: Purchase, 113,880 sh ($1.4M)2025-03-17: Purchase, 56,277 sh ($688K)2025-03-13: Purchase, 468,356 sh ($5.8M)2025-03-12: Purchase, 292,934 sh ($3.6M)2025-03-11: Purchase, 320,690 sh ($3.7M)2025-01-17: Purchase, 19,748 sh ($274K)2025-01-16: Purchase, 121,681 sh ($1.7M)2025-01-15: Purchase, 39,029 sh ($547K)2025-01-14: Purchase, 54,500 sh ($739K)2025-01-13: Purchase, 74,125 sh ($993K)2025-01-10: Purchase, 204,098 sh ($2.7M)2025-01-08: Purchase, 21,021 sh ($296K)2025-01-02: Purchase, 157,880 sh ($2.3M)2024-12-31: Purchase, 146,501 sh ($2.1M)2024-12-30: Purchase, 58,988 sh ($853K)2024-12-27: Purchase, 101,659 sh ($1.5M)2024-12-26: Purchase, 16,692 sh ($240K)2024-12-24: Purchase, 11,958 sh ($169K)2023-12-26: Purchase, 5,086,521 sh ($50.0M)
AKTS · 32 trades
2026-01-12: Purchase, 2,077,779 sh ($37.4M)2026-01-12: Purchase, 144,443 sh ($2.6M)2026-01-12: Conversion, 2,397,500 sh2026-01-12: Conversion, 488,891 sh2026-01-12: Conversion, 997,299 sh2026-01-12: Conversion, 9,913,810 sh2026-01-12: Conversion, 202,862 sh2026-01-12: Conversion, 2,270,879 sh2026-01-12: Conversion, 86,222 sh2026-01-12: Conversion, 965,190 sh2026-01-12: Conversion, 102,500 sh2026-01-12: Conversion, 2,397,500 sh2026-01-12: Conversion, 488,891 sh2026-01-12: Conversion, 997,299 sh2026-01-12: Conversion, 9,913,810 sh2026-01-12: Conversion, 128,506 sh2026-01-12: Conversion, 202,862 sh2026-01-12: Conversion, 2,270,879 sh2026-01-12: Conversion, 488,891 sh2026-01-12: Conversion, 997,299 sh2026-01-12: Conversion, 9,913,810 sh2026-01-12: Conversion, 128,506 sh2026-01-12: Conversion, 86,222 sh2026-01-12: Conversion, 965,190 sh2026-01-12: Conversion, 102,500 sh2026-01-12: Conversion, 128,506 sh2026-01-12: Conversion, 202,862 sh2026-01-12: Conversion, 2,270,879 sh2026-01-12: Conversion, 86,222 sh2026-01-12: Conversion, 965,190 sh2026-01-12: Conversion, 102,500 sh2026-01-12: Conversion, 2,397,500 sh
MRSN · 4 trades
2024-12-19: Other acquisition, 8,036,688 sh2024-12-19: Other acquisition, 8,036,688 sh2024-12-19: Other acquisition, 8,036,688 sh2024-12-19: Other acquisition, 8,036,688 sh
PRTA · 3 trades
2025-05-06: Sale, 1,984,053 sh ($15.2M)2025-05-05: Sale, 977,693 sh ($7.9M)2025-05-02: Sale, 3,317,938 sh ($27.7M)
ANAB · 3 trades
2025-01-02: Purchase, 6,646 sh ($86K)2024-12-31: Purchase, 13,268 sh ($172K)2024-12-30: Purchase, 65,184 sh ($842K)
ITOS · 2 trades
2025-05-15: Purchase, 3,300,000 sh ($26.4M)2025-05-14: Purchase, 1,658,978 sh ($12.3M)

Filing ledger

DateCompanyActionShares @ priceValueOwnership ΔOwned afterFiling
2026-05-07ATRAPurchase507,407 @ $9.35$4.7M+48.6% of holding1,552,000Form 4
2026-04-20TRAXSale4,705,575 @ $13.81$65.0Mownership Δ n/a3,174,519Form 4
2026-01-12AKTSPurchase2,077,779 @ $18.00$37.4M+91.5% of holding4,348,658Form 4
2026-01-12AKTSPurchase144,443 @ $18.00$2.6M+71.2% of holding347,305Form 4
2025-07-30—Sale27,433,338 @ $0.10$2.8M−21.5% of holding100,371,882Form 4
2025-07-29—Sale2,687,460 @ $0.10$272K−2.1% of holding127,805,220Form 4
2025-07-28—Sale33,931,740 @ $0.11$3.8M−20.6% of holding130,492,680Form 4
2025-05-19ZYMEPurchase5,919 @ $11.78$70K+0.0% of holding17,883,908Form 4
2025-05-15ITOSPurchase3,300,000 @ $8.00$26.4M+44.7% of holding10,688,978Form 4
2025-05-15ZYMEPurchase49,502 @ $11.43$566K+0.3% of holding17,877,989Form 4
2025-05-14ITOSPurchase1,658,978 @ $7.41$12.3M+29.0% of holding7,388,978Form 4
2025-05-06PRTASale1,984,053 @ $7.64$15.2M−27.2% of holding5,304,596Form 4
2025-05-05PRTASale977,693 @ $8.11$7.9M−11.8% of holding7,288,649Form 4
2025-05-02PRTASale3,317,938 @ $8.36$27.7M−28.6% of holding8,266,342Form 4
2025-04-17ZYMEPurchase54,760 @ $11.52$631K+0.3% of holding17,828,487Form 4
2025-04-16ZYMEPurchase73,953 @ $11.16$826K+0.4% of holding17,773,727Form 4
2025-04-04ZYMEPurchase196,438 @ $11.17$2.2M+1.1% of holding17,699,774Form 4
2025-04-03ZYMEPurchase120,770 @ $11.84$1.4M+0.7% of holding17,503,336Form 4
2025-04-02ZYMEPurchase74,360 @ $11.85$881K+0.4% of holding17,382,566Form 4
2025-04-01ZYMEPurchase48,658 @ $11.60$565K+0.3% of holding17,308,206Form 4
2025-03-31ZYMEPurchase4,397 @ $11.75$52K+0.0% of holding17,259,548Form 4
2025-03-26ZYMEPurchase43,848 @ $12.24$537K+0.3% of holding17,255,151Form 4
2025-03-25ZYMEPurchase53,501 @ $12.91$690K+0.3% of holding17,211,303Form 4
2025-03-24ZYMEPurchase22,689 @ $13.08$297K+0.1% of holding17,157,802Form 4
2025-03-21ZYMEPurchase31,033 @ $12.78$397K+0.2% of holding17,135,113Form 4
2025-03-20ZYMEPurchase73,476 @ $12.93$950K+0.4% of holding17,104,080Form 4
2025-03-19ZYMEPurchase58,306 @ $12.64$737K+0.3% of holding17,030,604Form 4
2025-03-18ZYMEPurchase113,880 @ $12.65$1.4M+0.7% of holding16,972,298Form 4
2025-03-17ZYMEPurchase56,277 @ $12.23$688K+0.3% of holding16,858,418Form 4
2025-03-13ZYMEPurchase468,356 @ $12.48$5.8M+2.9% of holding16,802,141Form 4
2025-03-12ZYMEPurchase292,934 @ $12.25$3.6M+1.8% of holding16,333,785Form 4
2025-03-11ZYMEPurchase320,690 @ $11.49$3.7M+2.0% of holding16,040,851Form 4
2025-01-17ZYMEPurchase19,748 @ $13.87$274K+0.1% of holding15,720,161Form 4
2025-01-16ZYMEPurchase121,681 @ $13.88$1.7M+0.8% of holding15,700,413Form 4
2025-01-15ZYMEPurchase39,029 @ $14.01$547K+0.3% of holding15,578,732Form 4
2025-01-14ZYMEPurchase54,500 @ $13.56$739K+0.4% of holding15,539,703Form 4
2025-01-13ZYMEPurchase74,125 @ $13.39$993K+0.5% of holding15,485,203Form 4
2025-01-10ZYMEPurchase204,098 @ $13.13$2.7M+1.3% of holding15,411,078Form 4
2025-01-08ZYMEPurchase21,021 @ $14.07$296K+0.1% of holding15,206,980Form 4
2025-01-02ZYMEPurchase157,880 @ $14.78$2.3M+1.1% of holding15,185,959Form 4
2025-01-02ANABPurchase6,646 @ $12.95$86K+0.1% of holding7,880,094Form 4
2024-12-31ZYMEPurchase146,501 @ $14.57$2.1M+1.0% of holding15,028,079Form 4
2024-12-31ANABPurchase13,268 @ $12.93$172K+0.2% of holding7,873,448Form 4
2024-12-30ZYMEPurchase58,988 @ $14.47$853K+0.4% of holding14,881,578Form 4
2024-12-30ANABPurchase65,184 @ $12.92$842K+0.8% of holding7,860,180Form 4
2024-12-27ZYMEPurchase101,659 @ $14.49$1.5M+0.7% of holding14,822,590Form 4
2024-12-26ZYMEPurchase16,692 @ $14.38$240K+0.1% of holding14,720,931Form 4
2024-12-24ZYMEPurchase11,958 @ $14.12$169K+0.1% of holding14,704,239Form 4
2023-12-26ZYMEPurchase5,086,521 @ $9.83$50.0Mownership Δ n/a5,086,521Form 4
37 award / exercise / gift records — not counted as purchases
DateCompanyActionSharesOwned afterFiling
2026-01-12AKTSConversion2,397,5000Form 4
2026-01-12AKTSConversion488,8910Form 4
2026-01-12AKTSConversion997,2990Form 4
2026-01-12AKTSConversion9,913,8100Form 4
2026-01-12AKTSConversion202,862202,862Form 4
2026-01-12AKTSConversion2,270,8792,270,879Form 4
2026-01-12AKTSConversion86,22286,222Form 4
2026-01-12AKTSConversion965,190965,190Form 4
2026-01-12AKTSConversion102,5000Form 4
2026-01-12AKTSConversion2,397,5000Form 4
2026-01-12AKTSConversion488,8910Form 4
2026-01-12AKTSConversion997,2990Form 4
2026-01-12AKTSConversion9,913,8100Form 4
2026-01-12AKTSConversion128,506128,506Form 4
2026-01-12AKTSConversion202,862202,862Form 4
2026-01-12AKTSConversion2,270,8792,270,879Form 4
2026-01-12AKTSConversion488,8910Form 4
2026-01-12AKTSConversion997,2990Form 4
2026-01-12AKTSConversion9,913,8100Form 4
2026-01-12AKTSConversion128,506128,506Form 4
2026-01-12AKTSConversion86,22286,222Form 4
2026-01-12AKTSConversion965,190965,190Form 4
2026-01-12AKTSConversion102,5000Form 4
2026-01-12AKTSConversion128,506128,506Form 4
2026-01-12AKTSConversion202,862202,862Form 4
2026-01-12AKTSConversion2,270,8792,270,879Form 4
2026-01-12AKTSConversion86,22286,222Form 4
2026-01-12AKTSConversion965,190965,190Form 4
2026-01-12AKTSConversion102,5000Form 4
2026-01-12AKTSConversion2,397,5000Form 4
2025-06-26ZYMEWithheld for tax4122,970,388Form 4
2025-06-26ZYMEExercise5,086,48022,970,388Form 4
2025-06-26ZYMEExercise5,086,5210Form 4
2024-12-19MRSNOther acquisition8,036,68811,328,000Form 4
2024-12-19MRSNOther acquisition8,036,6888,036,688Form 4
2024-12-19MRSNOther acquisition8,036,68811,328,000Form 4
2024-12-19MRSNOther acquisition8,036,6888,036,688Form 4

Source: SEC Form 4 filings. Each row links to its original filing.

Research tool, not investment advice — historical frequencies, not recommendations. A product of Marovel Technologies LLC. Full terms.