The shares are directly held by two Westlake funds, while their general partners and Dr. Beth C. Seidenberg may be deemed to have voting and dispositive power.
Rhea-AI Sentiment reads the wording of the document, how positive or negative its language is on a 1 to 5 scale. The balance of points shown with the takes weighs what the document actually discloses, so the two can disagree, for example when a trial that missed its main goal is described in upbeat language.
Electra Therapeutics, Inc. (ETRA) is the subject of a Schedule 13G reporting 6,347,539 shares of common stock, or 10.1% of the class, as beneficially owned by Dr. Beth C. Seidenberg as of September 30, 2026. Westlake BioPartners Fund I, L.P. directly holds 3,527,136 shares (5.6%), and Westlake BioPartners Fund II, L.P. directly holds 2,820,403 shares (4.5%). Their general partners and Seidenberg may be deemed to have sole voting and dispositive power over the respective holdings. Each reporting person disclaims beneficial ownership except to the extent of a pecuniary interest or shares held of record.
Key Figures
Beneficial ownership attributed to Dr. Beth C. Seidenberg:6,347,539 sharesClass ownership attributed to Dr. Beth C. Seidenberg:10.1%Westlake BioPartners Fund I, L.P. beneficial ownership:3,527,136 shares+3 more
6 metrics
Beneficial ownership attributed to Dr. Beth C. Seidenberg6,347,539 sharesAs of September 30, 2026
Class ownership attributed to Dr. Beth C. Seidenberg10.1%As of September 30, 2026
Westlake BioPartners Fund I, L.P. beneficial ownership3,527,136 sharesAs of September 30, 2026
Westlake BioPartners Fund I, L.P. class ownership5.6%As of September 30, 2026
Westlake BioPartners Fund II, L.P. beneficial ownership2,820,403 sharesAs of September 30, 2026
Westlake BioPartners Fund II, L.P. class ownership4.5%As of September 30, 2026
Key Terms
beneficial ownership, sole voting power, sole dispositive power, pecuniary interest
4 terms
beneficial ownershipregulatory
"disclaims beneficial ownership of such shares of Common Stock"
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
sole voting powerregulatory
"may be deemed to have sole voting power"
Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.
sole dispositive powerregulatory
"may be deemed to have sole dispositive power"
Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.
pecuniary interestfinancial
"Except to the extent of a Reporting Person's pecuniary interest therein"
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
How many ETRA shares does Dr. Beth C. Seidenberg report as beneficially owned?
Dr. Beth C. Seidenberg is reported to beneficially own 6,347,539 ETRA common shares, or 10.1% of the class, as of September 30, 2026. Westlake BioPartners Fund I, L.P. directly holds 3,527,136 shares, and Westlake BioPartners Fund II, L.P. directly holds 2,820,403 shares; Seidenberg may be deemed to have sole voting and dispositive power over them.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
Electra Therapeutics, Inc.
(Name of Issuer)
Common Stock, par value $0.0001 per share
(Title of Class of Securities)
284825106
(CUSIP Number)
09/30/2026
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
Rule 13d-1(b)
Rule 13d-1(c)
Rule 13d-1(d)
schemaVersion:
SCHEDULE 13G
CUSIP Number(s):
284825106
1
Names of Reporting Persons
Westlake BioPartners Fund I, L.P.
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
3,527,136.00
6
Shared Voting Power
3,527,136.00
7
Sole Dispositive Power
3,527,136.00
8
Shared Dispositive Power
3,527,136.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,527,136.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
5.6 %
12
Type of Reporting Person (See Instructions)
PN
Comment for Type of Reporting Person: Row 5 - 3,527,136 shares, except that Westlake BioPartners GP I, LLC ("Westlake GP I"), the general partner of Westlake BioPartners Fund I, L.P. ("Westlake Fund I"), may be deemed to have sole voting power, and Dr. Beth C. Seidenberg ("Seidenberg"), the sole managing director of Westlake GP I, may be deemed to have sole power to vote these shares.
Row 7 - 3,527,136 shares, except that Westlake GP I, the general partner of Westlake Fund I, may be deemed to have sole dispositive power, and Seidenberg, the sole managing director of Westlake GP I, may be deemed to have sole power to dispose of these shares.
SCHEDULE 13G
CUSIP Number(s):
284825106
1
Names of Reporting Persons
Westlake BioPartners GP I, LLC
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
3,527,136.00
6
Shared Voting Power
3,527,136.00
7
Sole Dispositive Power
3,527,136.00
8
Shared Dispositive Power
3,527,136.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,527,136.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
5.6 %
12
Type of Reporting Person (See Instructions)
OO
Comment for Type of Reporting Person: Row 5 - 3,527,136 shares, all of which are owned directly by Westlake Fund I. Westlake GP I, the general partner of Westlake Fund I, may be deemed to have sole voting power, and Seidenberg, the sole managing director of Westlake GP I, may be deemed to have sole power to vote these shares.
Row 7 - 3,527,136 shares, all of which are owned directly by Westlake Fund I. Westlake GP I, the general partner of Westlake Fund I, may be deemed to have sole dispositive power, and Seidenberg, the sole managing director of Westlake GP I, may be deemed to have sole power to dispose of these shares.
SCHEDULE 13G
CUSIP Number(s):
284825106
1
Names of Reporting Persons
Westlake BioPartners Fund II, L.P.
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
2,820,403.00
6
Shared Voting Power
2,820,403.00
7
Sole Dispositive Power
2,820,403.00
8
Shared Dispositive Power
2,820,403.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,820,403.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
4.5 %
12
Type of Reporting Person (See Instructions)
PN
Comment for Type of Reporting Person: Row 5 - 2,820,403 shares, except that Westlake BioPartners GP II, LLC ("Westlake GP II"), the general partner of Westlake BioPartners Fund II, L.P. ("Westlake Fund II"), may be deemed to have sole voting power, and Seidenberg, the sole managing director of Westlake GP II, may be deemed to have sole power to vote these shares.
Row 7 - 2,820,403 shares, except that Westlake GP II, the general partner of Westlake Fund II, may be deemed to have sole dispositive power, and Seidenberg, the sole managing director of Westlake GP II, may be deemed to have sole power to dispose of these shares.
SCHEDULE 13G
CUSIP Number(s):
284825106
1
Names of Reporting Persons
Westlake BioPartners GP II, LLC
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
2,820,403.00
6
Shared Voting Power
2,820,403.00
7
Sole Dispositive Power
2,820,403.00
8
Shared Dispositive Power
2,820,403.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,820,403.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
4.5 %
12
Type of Reporting Person (See Instructions)
OO
Comment for Type of Reporting Person: Row 5 - 2,820,403 shares, all of which are owned directly by Westlake Fund II. Westlake GP II, the general partner of Westlake Fund II, may be deemed to have sole voting power, and Seidenberg, the sole managing director of Westlake GP II, may be deemed to have sole power to vote these shares.
Row 7 - 2,820,403 shares, all of which are owned directly by Westlake Fund II. Westlake GP II, the general partner of Westlake Fund II, may be deemed to have sole dispositive power, and Seidenberg, the sole managing director of Westlake GP II, may be deemed to have sole power to dispose of these shares.
SCHEDULE 13G
CUSIP Number(s):
284825106
1
Names of Reporting Persons
Dr. Beth C. Seidenberg
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
6,347,539.00
6
Shared Voting Power
6,347,539.00
7
Sole Dispositive Power
6,347,539.00
8
Shared Dispositive Power
6,347,539.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,347,539.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
10.1 %
12
Type of Reporting Person (See Instructions)
IN
Comment for Type of Reporting Person: Row 5 - 6,347,539 shares, of which 3,527,136 shares are held directly by Westlake Fund I and 2,820,403 shares are held directly by Westlake Fund II. Westlake GP I is the general partner of Westlake Fund I, and Westlake GP II is the general partner of Westlake Fund II. Seidenberg, as the sole managing director of each of Westlake GP I and Westlake GP II, may be deemed to have sole voting power over the shares held directly by each of Westlake Fund I and Westlake Fund II.
Row 7 - 6,347,539 shares, of which 3,527,136 shares are held directly by Westlake Fund I and 2,820,403 shares are held directly by Westlake Fund II. Seidenberg, as the sole managing director of each of Westlake GP I and Westlake GP II, may be deemed to have sole dispositive power over the shares held directly by each of Westlake Fund I and Westlake Fund II.
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Electra Therapeutics, Inc.
(b)
Address of issuer's principal executive offices:
230 East Grand Avenue, Suite S-100 South San Francisco, CA 94080
Item 2.
(a)
Name of person filing:
This Statement is being filed by Westlake BioPartners Fund I, L.P. ("Westlake Fund I"), Westlake BioPartners GP I, LLC ("Westlake GP I"), Westlake BioPartners Fund II, L.P. ("Westlake Fund II"), Westlake BioPartners GP II, LLC ("Westlake GP II") and Dr. Beth C. Seidenberg ("Seidenberg") (collectively, the "Reporting Persons").
(b)
Address or principal business office or, if none, residence:
The address of the principal business office of each Reporting Person is c/o Westlake BioPartners, LLC, 3075 Townsgate Road, Suite 140, Westlake Village, California 91361.
(c)
Citizenship:
Each of Westlake GP I and Westlake GP II is a limited liability company organized under the laws of the State of Delaware. Each of Westlake Fund I and Westlake Fund II is a limited partnership organized under the laws of the State of Delaware. Seidenberg is a citizen of the United States of America.
(d)
Title of class of securities:
Common Stock, par value $0.0001 per share
(e)
CUSIP Number(s):
284825106
Item 3.
If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)
Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)
An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)
An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)
A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)
A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)
A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
See Row 9 of the cover page for each Reporting Person.*
(b)
Percent of class:
See Row 11 of the cover page for each Reporting Person.*
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
See Row 5 of the cover page for each Reporting Person.*
(ii) Shared power to vote or to direct the vote:
See Row 6 of the cover page for each Reporting Person.*
(iii) Sole power to dispose or to direct the disposition of:
See Row 7 of the cover page for each Reporting Person.*
(iv) Shared power to dispose or to direct the disposition of:
See Row 8 of the cover page for each Reporting Person.*
* Except to the extent of a Reporting Person's pecuniary interest therein, each Reporting Person disclaims beneficial ownership of such shares of Common Stock, except for the shares, if any, such Reporting Person holds of record.
Item 5.
Ownership of 5 Percent or Less of a Class.
Not Applicable
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
Under certain circumstances set forth in the limited partnership agreement of each of Westlake Fund I and Westlake Fund II and the limited liability company agreement of each of Westlake GP I and Westlake GP II, the general and limited partners or members, as the case may be, of each of such entities may be deemed to have the right to receive dividends from, or the proceeds from, the sale of securities of the Issuer owned by each such entity of which they are a partner or member, as the case may be.
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
Not Applicable
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
Not Applicable
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.
Westlake BioPartners Fund I, L.P.
Signature:
Westlake BioPartners GP I, LLC
Name/Title:
General Partner
Date:
10/27/2026
Signature:
/s/ Jennifer L. Kercher
Name/Title:
Jennifer L. Kercher/Attorney-in-Fact*
Date:
10/27/2026
Westlake BioPartners GP I, LLC
Signature:
/s/ Jennifer L. Kercher
Name/Title:
Jennifer L. Kercher/Attorney-in-Fact*
Date:
10/27/2026
Westlake BioPartners Fund II, L.P.
Signature:
Westlake BioPartners GP II, LLC
Name/Title:
General Partner
Date:
10/27/2026
Signature:
/s/ Jennifer L. Kercher
Name/Title:
Jennifer L. Kercher/Attorney-in-Fact*
Date:
10/27/2026
Westlake BioPartners GP II, LLC
Signature:
/s/ Jennifer L. Kercher
Name/Title:
Jennifer L. Kercher/Attorney-in-Fact*
Date:
10/27/2026
Dr. Beth C. Seidenberg
Signature:
/s/ Jennifer L. Kercher
Name/Title:
Jennifer L. Kercher/Attorney-in-Fact*
Date:
10/27/2026
Comments accompanying signature: * This Schedule 13G was executed pursuant to a Power of Attorney. Note that copies of the applicable Powers of Attorney are included herein as exhibits to this Schedule 13G.
Exhibit Information
EXHIBIT INDEX
Exhibit Description
1 Joint Filing Agreement
2 Power of Attorney - Westlake BioPartners Fund I, L.P. and Westlake BioPartners GP I, LLC
3 Power of Attorney - Westlake BioPartners Fund II, L.P. and Westlake BioPartners GP II, LLC
