Westlake BioPartners Fund I, Westlake BioPartners Fund II, their respective general partners, and Dr. Beth C. Seidenberg filed a Schedule 13G with the SEC on October 29, 2026, disclosing beneficial ownership of common stock in Electra Therapeutics, Inc. as of September 30, 2026.

Key Highlights

  • Dr. Beth C. Seidenberg is reported as beneficially owning 6,347,539 shares, representing 10.1% of Electra Therapeutics common stock.
  • Westlake BioPartners Fund I, L.P. directly holds 3,527,136 shares, equal to 5.6% of the class.
  • Westlake BioPartners Fund II, L.P. directly holds 2,820,403 shares, equal to 4.5% of the class.
  • Seidenberg serves as the sole managing director of both Westlake BioPartners GP I, LLC and Westlake BioPartners GP II, LLC, which are the general partners of Fund I and Fund II, respectively.
  • The triggering event date for this filing is September 30, 2026, according to the filing.
  • All reporting persons are organized or domiciled in Delaware, except Seidenberg, who is a citizen of the United States.

Westlake BioPartners and Seidenberg Position in Electra Therapeutics Common Stock

According to the Schedule 13G filed with the SEC, five reporting persons collectively disclosed beneficial ownership of shares of common stock, par value $0.0001 per share, in Electra Therapeutics, Inc. (NASDAQ:ETRA), with the triggering event dated September 30, 2026. The filing was made on behalf of Westlake BioPartners Fund I, L.P., Westlake BioPartners GP I, LLC, Westlake BioPartners Fund II, L.P., Westlake BioPartners GP II, LLC, and Dr. Beth C. Seidenberg, whose shared principal business address is listed as c/o Westlake BioPartners, LLC, 3075 Townsgate Road, Suite 140, Westlake Village, California 91361.

The filing reports that Westlake BioPartners Fund I, L.P. directly holds 3,527,136 shares, representing 5.6% of the class, while Westlake BioPartners Fund II, L.P. directly holds 2,820,403 shares, representing 4.5% of the class. At the individual level, Dr. Seidenberg is reported as beneficially owning a combined 6,347,539 shares, or 10.1% of the class, comprising the holdings of both funds. The filing notes that Seidenberg, "as the sole managing director of each of Westlake GP I and Westlake GP II, may be deemed to have sole voting power" and "sole dispositive power" over the shares held directly by each fund.

The filing states that Westlake BioPartners GP I, LLC and Westlake BioPartners GP II, LLC each "may be deemed to have sole voting power" and "sole dispositive power" over the shares held by their respective funds. The securities disclosed are Electra Therapeutics common stock with CUSIP number 284825106. The issuer's principal executive offices are listed as 230 East Grand Avenue, Suite S-100, South San Francisco, CA 94080.

What Was Disclosed

The Schedule 13G discloses that Westlake BioPartners-affiliated entities and Dr. Beth C. Seidenberg reported aggregate beneficial ownership of 6,347,539 shares, or 10.1%, of Electra Therapeutics common stock as of September 30, 2026, with the filing submitted October 29, 2026.