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SCHEDULE Filed 2025-02-18 Event 2025-02-17 SEC 0000935836-25-000186 →

EcoR1 Capital, LLC Zymeworks Inc. ZYME

Stake: 22.80% Shares: 15,720,161 CUSIP: 98985Y108 Class: Common Stock

Item 4 — Purpose of Transaction

The reporting persons are filing this Schedule 13D because Oleg Nodelman, the manager of EcoR1, was appointed to the Issuer's board of directors on February 17, 2025. In addition, one of EcoR1's employees, Scott Platshon, is also on the Issuer's board of directors. The reporting persons acquired the Stock for investment purposes based on their belief that the Issuer's Common Stock, when purchased, was undervalued and represented an attractive investment opportunity. The reporting persons will routinely monitor the Issuer regarding a wide variety of factors that affect their investment considerations, including, current and anticipated future trading prices of the Common Stock and other securities, the Issuer's operations, assets, prospects, financial position, and business development, Issuer's management, Issuer-related competitive and strategic matters, general economic, financial market and industry conditions, and other investment considerations. Depending on their evaluation of various factors, the reporting persons may take such actions regarding their holdings of the Issuer's securities as they deem appropriate in light of circumstances existing from time to time. Such actions may include purchasing additional Common Stock in the open market, through privately negotiated transactions with third parties or otherwise, and selling at any time, in the open market, through privately negotiated transactions with third parties or otherwise, all or part of the Common Stock that they now own or hereafter acquire. The reporting persons also may from time to time enter into or unwind hedging or other derivative transactions with respect to the Common Stock or pledge their interests in the Common Stock to obtain liquidity. In addition, from time to time the reporting persons and their representatives and advisers may communicate with other stockholders, industry participants and other interested parties about the Issuer. The reporting persons have no present plan or proposal that relates to or would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D. However, the reporting persons may recommend action to the Issuer's management, board of directors and stockholders. Any such actions could involve one or more of the events referred to in clauses (a) through (j) of Item 4 of Schedule 13D, including, potentially, one or more mergers, consolidations, sales or acquisitions of assets, changes in control, issuances, purchases, dispositions or pledges of securities or other changes in capitalization.

Cross-References

Insider Activity (last 365d)
68 transactions
38 buys · 10 sales · 20 awards/exercises
Issuer Cluster
3 13D/G filings on this issuer
2 other filings besides this one
Filer Track Record
13 filings by this filer
12 other filings in the data moat
Short Interest · settle 2026-07-15
DTC 7.56
4,102,257 shares short · -6.0% vs prior

Post-Filing Returns · since 2025-02-17 on ZYME

+1 day
0.0%
+5 days
0.0%
+30 days
0.0%
+60 days
0.0%
+90 days
0.0%
+180 days
0.0%

Anchor price 26.72 on closest trading day on/after 2025-02-17. Source: Yahoo Finance daily adj_close (split + dividend adjusted).

Form 4 Insider Transactions · last 365d

DateInsiderRoleTypeSharesPriceValue
2026-05-13 Schneider Paul R officer Award 178,000 $24.57 $4.37M
2026-05-13 Schneider Paul R officer Award 119,000
2026-04-09 Schayowitz Adam officer Award 70,000 $27.35 $1.91M
2026-04-09 Platshon Scott officer Award 70,000 $27.35 $1.91M
2026-04-09 Platshon Scott officer Award 47,000
2026-04-09 Platshon Scott officer Award 76,000
2026-04-09 Schayowitz Adam officer Award 47,000
2026-04-09 Schayowitz Adam officer Award 76,000
2026-04-06 Stafford Kristin officer Award 178,000 $25.84 $4.60M
2026-04-06 Stafford Kristin officer Award 119,000
2026-04-06 Stafford Kristin officer Award 50,000
2026-01-12 Hollywood Mark officer Option exercise 17,666
2026-01-12 Cherry Brian N director Award 23,000 $23.16 $533K
2026-01-12 Smith Jeffrey T L officer Option exercise 17,666
2026-01-12 Ciongoli Gregory Austin director Award 11,500 $23.16 $266K
2026-01-12 Neu Kelvin director Award 11,500 $23.16 $266K
2026-01-12 Landry Robert E director Award 11,500 $23.16 $266K
2026-01-12 Cesano Alessandra director Award 11,500 $23.16 $266K
2026-01-12 Campoy Carlos director Award 11,500 $23.16 $266K
2026-01-12 Mahony Susan director Award 11,500 $23.16 $266K
2026-01-12 Moore Paul Andrew officer Option exercise 17,666
2026-01-12 Galbraith Kenneth director, officer Option exercise 64,000
2026-01-12 Galbraith Kenneth director, officer Sale 30,424 $22.67 $690K
2026-01-12 Galbraith Kenneth director, officer Option exercise 64,000
2026-01-12 Galbraith Kenneth director, officer Award 216,000 $23.16 $5.00M
Showing 25 of 68

Other 13D/G Filings on Zymeworks Inc.

FiledFormFilerStakeShares
2025-03-17 SCHEDULE EcoR1 Capital, LLC 24.20% 16,858,418 view →
2025-01-13 SCHEDULE EcoR1 Capital, LLC 22.40% 15,411,078 view →

Other Filings by EcoR1 Capital, LLC

FiledFormIssuerStakeShares
2026-07-20 SCHEDULE 13G Alto Neuroscience, Inc. view →
2026-06-25 SCHEDULE 13G Fulcrum Therapeutics, Inc. FULC view →
2026-06-25 SCHEDULE 13G Fulcrum Therapeutics, Inc. FULC view →
2026-06-16 SCHEDULE 13G Eloxx Pharmaceuticals, Inc. ELOX view →
2025-05-19 SCHEDULE GALAPAGOS NV GLPGF 11.84% 7,803,202 view →
2025-03-17 SCHEDULE Zymeworks Inc. ZYME 24.20% 16,858,418 view →
2025-01-13 SCHEDULE Zymeworks Inc. ZYME 22.40% 15,411,078 view →
2025-01-03 SCHEDULE PROTHENA CORP PUBLIC LTD CO PRTA 21.50% 11,584,280 view →
2024-10-08 SC GALAPAGOS NV GLPGF view →
2022-01-14 SC PROTHENA CORP PUBLIC LTD CO PRTA view →
2021-05-11 SC ANAPTYSBIO, INC ANABV view →
2021-04-13 SC ANAPTYSBIO, INC ANABV view →

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