[SCHEDULE 13D] Zymeworks Inc. SEC Filing

Rhea-AI Filing Summary

EcoR1 Capital, LLC and affiliates have filed a Schedule 13D disclosing a 30.7% beneficial stake in Zymeworks Inc. (NASDAQ: ZYME). The group, which includes EcoR1 Capital Fund Qualified, L.P. and EcoR1 founder Oleg Nodelman, now controls 22,970,388 common shares following the recent exercise of pre-funded warrants. The ownership percentage is based on 74,844,505 shares outstanding as reported in Zymeworks’ Form 8-K dated 27 Jun 2025.

Capital deployed. EcoR1 funds have invested a cumulative $205.7 million in ZYME equity: $192.9 million by the Qualified Fund and $12.9 million by EcoR1 Capital Fund, L.P. The totals include $50.0 million used on 26 Dec 2023 to acquire pre-funded warrants that have since been exercised.

Governance influence. Oleg Nodelman and EcoR1 employee Scott Platshon already sit on Zymeworks’ board, giving the investor direct insight and influence over corporate strategy. The filing states that the shares were acquired for investment purposes and that no specific plans under Items 4(a)-(j) of Schedule 13D are currently contemplated; however, EcoR1 reserves the right to buy or sell additional shares, engage in hedging, or discuss strategic matters with management and other shareholders.

Key takeaways for investors:

• EcoR1 is now Zymeworks’ largest known holder, with voting and dispositive power shared among its entities.
• The stake underscores EcoR1’s conviction that ZYME was undervalued at the time of purchase.
• While the filing is not overtly activist, EcoR1’s 30%-plus position and board presence could accelerate strategic initiatives or heighten takeover speculation.
• Potential share-price volatility may arise if EcoR1 materially increases or reduces its position.

Positive

• EcoR1 now owns 30.7% of Zymeworks’ outstanding shares, indicating significant confidence in the company’s valuation and prospects.
• More than $205 million of capital deployed to build the position, highlighting strong financial commitment.
• Board representation by EcoR1 principals enhances alignment between the investor and corporate strategy.

Negative

• High ownership concentration could reduce float and amplify volatility if EcoR1 changes its position.
• Filing specifies right to sell or hedge at any time, creating an overhang risk for minority shareholders.

Insights

Portfolio Manager

TL;DR: EcoR1’s 30.7% stake signals high conviction and creates a strategic overhang—generally bullish but watch concentration risk.

EcoR1 has deployed over $200 million to accumulate nearly one-third of ZYME’s equity, aligning its economic interests with other shareholders. Its board representation provides informational advantages and potential sway over capital-allocation decisions. Although the filing notes no current activist agenda, EcoR1 retains flexibility to push for transactions that could unlock value. From a portfolio standpoint, increased insider support typically lowers perceived downside risk and can attract additional institutional interest. That said, concentrated ownership heightens liquidity risk and could amplify price swings if EcoR1 trims its position. Overall impact skews positive given the scale of commitment and governance access.

Corporate Governance Expert

TL;DR: Large insider-like stake improves oversight but raises minority-shareholder influence concerns; impact is material yet balanced.

EcoR1’s control of more than 30% of outstanding shares, coupled with two board seats, gives the fund substantial influence over strategic direction without triggering formal change-of-control mechanisms. The group expressly disclaims any current plans under Item 4, reducing immediate takeover risk. However, its ability to pivot quickly—buying more stock, advocating M&A, or exiting—creates an overhang that minority investors must monitor. Regulatory history shows no legal impediments, and funds were sourced from working capital, limiting financing uncertainty. Net-net, governance quality may improve through active oversight, but shareholder-rights implications warrant vigilance.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

Zymeworks Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

98985Y108

(CUSIP Number)

Anthony J. Caldwell, Esq.
Shartsis Friese, LLP, 425 Market Street, 11th Floor
San Francisco, CA, 94105
415-421-6500

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

06/26/2025

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No. 98985Y108

1

Name of reporting person

EcoR1 Capital, LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 22,970,388.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 22,970,388.00

11

Aggregate amount beneficially owned by each reporting person

22,970,388.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

30.7 %

14

Type of Reporting Person (See Instructions)

IA, OO

Comment for Type of Reporting Person:

Percentage calculated based on 74,844,505 shares of Common Stock outstanding following the exercise of Pre-Funded Warrants by the reporting persons, as reported in the Form 8-K filed by the Issuer on June 27, 2025.

SCHEDULE 13D

CUSIP No. 98985Y108

1

Name of reporting person

Oleg Nodelman

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 22,970,388.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 22,970,388.00

11

Aggregate amount beneficially owned by each reporting person

22,970,388.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

30.7 %

14

Type of Reporting Person (See Instructions)

IN, HC

Comment for Type of Reporting Person:

Percentage calculated based on 74,844,505 shares of Common Stock outstanding following the exercise of Pre-Funded Warrants by the reporting persons, as reported in the Form 8-K filed by the Issuer on June 27, 2025.

SCHEDULE 13D

CUSIP No. 98985Y108

1

Name of reporting person

EcoR1 Capital Fund Qualified, L.P.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 21,582,563.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 21,582,563.00

11

Aggregate amount beneficially owned by each reporting person

21,582,563.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

28.8 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person:

Percentage calculated based on 74,844,505 shares of Common Stock outstanding following the exercise of Pre-Funded Warrants by the reporting persons, as reported in the Form 8-K filed by the Issuer on June 27, 2025.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock
(b)	Name of Issuer: Zymeworks Inc.
(c)	Address of Issuer's Principal Executive Offices: 108 PATRIOT DRIVE, SUITE A, MIDDLETOWN, DELAWARE , 19709.
Item 2.	Identity and Background
(a)	The reporting persons are: EcoR1 Capital, LLC, a Delaware limited liability company ("EcoR1") EcoR1 Capital Fund Qualified, L.P., a Delaware limited partnership ("Qualified Fund") Oleg Nodelman Qualified Fund is filing this statement jointly with the other reporting persons, but not as a member of a group, and it expressly disclaims membership in a group. In addition, the filing of this Schedule 13D on behalf of Qualified Fund should not be construed as an admission that it is, and it disclaims that it is, a beneficial owner, as defined in Rule 13d-3 under the Act, of any securities covered by this Schedule 13D. Each reporting person also disclaims beneficial ownership of the securities reported herein except to the extent of that person's pecuniary interest therein.
(b)	357 Tehama Street #3, San Francisco, CA 94103
(c)	EcoR1 is an investment adviser to investment funds, including Qualified Fund (collectively, the "Funds"). EcoR1 is the general partner of the Funds. Mr. Nodelman is the manager and control person of EcoR1.
(d)	During the last five years, none of the reporting persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).
(e)	During the last five years, none of the reporting persons was a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(f)	For citizenship of the reporting persons, see Item 6 of each reporting person's cover page.
Item 3.	Source and Amount of Funds or Other Consideration
	The Funds used their working capital to purchase the Issuer's Common Stock and Pre-Funded Warrants to purchase the Issuer's Common Stock. The amount of funds used in purchasing the Issuer's Common Stock were as follows: EcoR1 Capital Fund Qualified, L.P.: $192,880,935.01 EcoR1 Capital Fund, L.P.: $12,853,702.36 The foregoing amount of funds includes the following amounts used in purchasing Pre-Funded Warrants to purchase the Issuer's Common Stock on December 26, 2023: EcoR1 Capital Fund Qualified, L.P.: $47,364,999.62 EcoR1 Capital Fund, L.P.: $2,634,993.17
Item 4.	Purpose of Transaction
	Oleg Nodelman, the manager of EcoR1, and Scott Platshon, one of EcoR1's employees, are members of the Issuer's board of directors. The reporting persons acquired the Common 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.
Item 5.	Interest in Securities of the Issuer
(a)	Aggregate number of shares beneficially owned by the reporting persons: EcoR1: 22,970,388 Oleg Nodelman: 22,970,388 Qualified Fund: 21,582,563 Aggregate percentage of the class of stock beneficially owned by the reporting persons: EcoR1: 30.7% Oleg Nodelman: 30.7% Qualified Fund: 28.8%
(b)	Number of shares as to which each reporting person has: i) Sole power to vote or to direct the vote: EcoR1: 0 Oleg Nodelman: 0 Qualified Fund: 0 (ii) Shared power to vote or to direct the vote: EcoR1: 22,970,388 Oleg Nodelman: 22,970,388 Qualified Fund: 21,582,563 (iii) Sole power to dispose or to direct the disposition of: EcoR1: 0 Oleg Nodelman: 0 Qualified Fund: 0 (iv) Shared power to dispose or to direct the disposition of: EcoR1: 22,970,388 Oleg Nodelman: 22,970,388 Qualified Fund: 21,582,563
(c)	The reporting persons engaged in the following transactions in the Issuer's Common Stock in the 60 days preceding the date of this Schedule 13D: On 5/15/2025, the Funds purchased 49,502 shares of the Issuer's Common Stock for a price of $11.4308 per share. Qualified Fund purchased 46,405 of these shares. On 5/19/2025, the Funds purchased 5,919 shares of the Issuer's Common Stock for a price of $11.7821 per share. Qualified Fund purchased 5,550 of these shares. On 6/26/2025, the Funds exercised Pre-Funded Warrants to purchase 5,086,521 shares of the Issuer's Common Stock for $0.0001 per share. Qualified Fund exercised warrants to purchase 4,818,462 of these shares. The reporting persons paid the exercise price on a cashless basis, resulting in the Issuer withholding 41 of the warrant shares (including 38 warrant shares issuable to Qualified Fund) to pay the exercise price and issuing to the reporting persons the remaining 5,086,480 shares.
(d)	Not applicable.
(e)	Not applicable.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	EcoR1 is the investment adviser to its clients pursuant to investment management agreements or limited partnership agreements providing to EcoR1 the authority, among other things, to invest the funds of such clients in Stock, to vote and dispose of Stock and to file this statement on behalf of such clients. Pursuant to such limited partnership agreements, EcoR1 is entitled to allocations based on assets under management and realized and unrealized gains. Pursuant to such investment management agreements, EcoR1 is entitled to fees based on assets under management and realized and unrealized gains. Securities Purchase Agreement On December 23, 2023, the reporting persons entered into a securities purchase agreement (the "Securities Purchase Agreement") for a private placement with the Issuer. Pursuant to the Securities Purchase Agreement, the reporting persons purchased pre-funded warrants (the "Pre-Funded Warrants") to purchase 5,086,521 shares of Common Stock of the Issuer (the "Warrant Shares"). In addition, the Issuer agreed that EcoR1 had the right to nominate one of its partners as a member of the board of directors of the Issuer, subject to specified conditions. EcoR1 exercised this right to appoint Scott Platshon to the Issuer's board of directors. Pre-Funded Warrants The Pre-Funded Warrants were exercisable at an exercise price equal to $0.0001 per share, subject to adjustments as provided under the terms of the Pre-Funded Warrants. The Pre-Funded Warrants were exercisable at any time. On June 26, 2025, the Funds and the Issuer entered into an Amendment No. 1 to the Pre-Funded Warrants to remove the limitation that the Pre-Funded Warrants cannot be exercised if, after giving effect or immediately prior to such exercise, the reporting persons, together with their affiliates and any other persons whose beneficial ownership of shares of Common Stock would be aggregated with the reporting persons for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), would beneficially own more than 19.99% of the total number of issued and outstanding shares of Common Stock or voting power of the Issuer following such exercise. The Funds exercised the Pre-Funded W arrants in full on June 26, 2025. Registration Rights Agreement The reporting persons also entered into a registration rights agreement (the "Registration Rights Agreement") with the Issuer on December 23, 2023, requiring the Issuer to register the resale of the Warrant Shares (the "Registrable Securities"). Under the Registration Rights Agreement, the Issuer agreed to file a registration statement covering the resale by the reporting persons of their Registrable Securities upon the earlier of March 15, 2024 and the first business day following the date that the Issuer files it Annual Report on Form 10-K for the fiscal year ended December 31, 2023 (the "Filing Deadline"). The Issuer agreed to use commercially reasonable efforts to cause such registration statement or final prospectus, as applicable, to be declared effective as soon as practicable, but no later than the later of April 29, 2024 and the 123rd calendar day following the closing date (the "Effectiveness Deadline"), and to keep such registration statement effective for a period that will terminate upon the earliest of (i) the date that all Registrable Securities covered by such registration statement or final prospectus, as applicable, have been sold, (ii) the date that all Registrable Securities covered by such registration statement or final prospectus, as applicable, may be sold without the requirement for the Issuer to be in compliance with the current public information required under Rule 144 as to such Registrable Securities and without volume or manner-of-sale restrictions and (iii) two (2) years after the date of the Securities Purchase Agreement. The Issuer agreed to be responsible for all reasonable expenses in connection with the filing of any registration statement or final prospectus, as applicable. For the avoidance of doubt, the fees and expenses of the reporting persons' counsel shall be the responsibility of the reporting persons, and not the Issuer. In the event (i) the registration statement or final prospectus, as applicable, covering the Registrable Securities has not been filed with the Securities and Exchange Commission (the "SEC") on or prior to the Filing Deadline, (ii) the registration statement or final prospectus, as applicable, covering the Registrable Securities is not declared effective by the SEC prior to the earlier of (a) ten (10) business days after the date on which the Issuer is notified by the SEC that the registration statement or final prospectus, as applicable, will not be reviewed by the SEC or is not subject to further comment by the SEC and (b) the Effectiveness Deadline, or (iii) after the registration statement or final prospectus, as applicable, has been declared effective by the SEC, sales cannot be made pursuant to the registration statement or final prospectus, as applicable, for any reason, subject to certain limited exceptions, then the Issuer has agreed to make pro rata payments to each reporting person as liquidated damages and not as a penalty, in an amount equal to one percent (1%) of the aggregate purchase price paid by such Issuer pursuant to the Securities Purchase Agreement for any shares of Common Stock held by such Issuer pursuant to the exercise of Pre-Funded Warrants but not for any unissued shares of Common Stock issuable upon exercise of the Pre-Funded Warrants for each 30-day period or pro rata for any portion thereof (a) following the Filing Deadline for which no registration statement or final prospectus, as applicable, is filed with respect to the Registrable Securities or (b) during which such registration statement or final prospectus, as applicable, is unavailable, as applicable. Payment of such liquidated damages shall be the reporting persons' exclusive remedy for such events. In addition, (i) the aggregate amount of liquidated damages payable to a reporting person shall not exceed, in the aggregate, six percent (6%) of the aggregate purchase price paid by such reporting person and (ii) the Issuer shall not be liable in any thirty (30) day period for liquidated damages in excess of one percent (1%) of the aggregate purchase price paid by the reporting person. The Issuer has granted the reporting persons customary indemnification rights in connection with the registration statement. The reporting persons have also granted the Issuer customary indemnification rights in connection with the registration statement. The foregoing description of the material terms of the Securities Purchase Agreement, the Registration Rights Agreement, the Pre-Funded Warrant and Amendment No. 1 to the Pre-Funded Warrants is qualified in its entirety by reference to those documents, each of which is referenced in Exhibits 99.2, 99.3, 99.4 and 99.5 hereto, respectively, and is incorporated by reference herein.
Item 7.	Material to be Filed as Exhibits.
	Exhibit 99.1 - Agreement Regarding Joint Filing of Statement on Schedule 13D or 13G. Exhibit 99.2 - Securities Purchase Agreement, dated December 23, 2023, by and among the Issuer and the reporting persons, attached as Exhibit 10.1 to the Issuer's Form 8-K filed on December 26, 2023. Exhibit 99.3 - Registration Rights Agreement, dated December 23, 2023, by and among the Issuer and the reporting persons, attached as Exhibit 10.2 to the Issuer's Form 8-K filed on December 26, 2023. Exhibit 99.4 - Form of Pre-Funded Warrant, attached as Exhibit 10.3 to the Issuer's Form 8-K filed on December 26, 2023. Exhibit 99.4 - Amendment No. 1 to Pre-Funded Warrant, attached as Exhibit 10.1 to the Issuer's Form 8-K filed on June 27, 2025.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

EcoR1 Capital, LLC

Signature:	/s/ Oleg Nodelman
Name/Title:	Manager
Date:	06/27/2025

Oleg Nodelman

Signature:	/s/ Oleg Nodelman
Name/Title:	Reporting person
Date:	06/27/2025

EcoR1 Capital Fund Qualified, L.P.

Signature:	/s/ Oleg Nodelman
Name/Title:	Manager of the General Partner, EcoR1 Capital, LLC
Date:	06/27/2025

FAQ

How many ZYME shares does EcoR1 Capital own after this filing?

EcoR1 and affiliates report 22,970,388 common shares, representing 30.7 % of shares outstanding.

What is the cost basis of EcoR1’s investment in Zymeworks?

The funds spent $205.7 million in aggregate, including roughly $50 million for pre-funded warrants acquired on 26 Dec 2023.

Does EcoR1 plan to take control of Zymeworks?

The Schedule 13D states no current plan or proposal for actions listed in Item 4(a)-(j), but EcoR1 may buy, sell, or engage with management as circumstances evolve.

Who represents EcoR1 on Zymeworks’ board of directors?

Oleg Nodelman, EcoR1’s manager, and Scott Platshon, an EcoR1 employee, currently sit on the board.

What percentage of Zymeworks’ shares was used to calculate EcoR1’s ownership?

Ownership is based on 74,844,505 shares outstanding, per Zymeworks’ Form 8-K filed 27 Jun 2025.