Third Rock Ventures VI, L.P. and related entities filed a Schedule 13G on October 26, 2026, disclosing beneficial ownership of 990,000 Class A ordinary shares of TCGX Acquisition Corp. II following the company's initial public offering on October 19, 2026.

Key Highlights

  • 990,000 shares reported: Third Rock Ventures VI, L.P. directly owns 990,000 Class A ordinary shares of TCGX Acquisition Corp. II, according to the filing.
  • 9.5% of class: The 990,000 shares represent approximately 9.5% of the 10,450,000 Class A ordinary shares outstanding following the IPO and concurrent private placement.
  • Shared voting and dispositive power only: All three reporting persons report zero sole voting power and zero sole dispositive power; all 990,000 shares are held with shared voting and shared dispositive power.
  • Three reporting persons: The filers are Third Rock Ventures VI, L.P.; its general partner, Third Rock Ventures GP VI, L.P.; and its general partner, TRV GP VI, LLC, all organized in Delaware.
  • Triggering event was the IPO close: The date of the event requiring this filing is listed as October 19, 2026, the closing date of the issuer's initial public offering and concurrent private placement.
  • Signed by Kevin Gillis: The statement was signed on October 26, 2026, by Kevin Gillis in his capacity as Chief Operating Officer of TRV GP VI, LLC on behalf of all three reporting persons.

Third Rock Ventures Entities Report Post-IPO Ownership in TCGX Acquisition Corp. II

According to the Schedule 13G filed on October 26, 2026, Third Rock Ventures VI, L.P. directly holds 990,000 Class A ordinary shares of TCGX Acquisition Corp. II (CUSIP G87082106), a position that arose from the closing of the issuer's initial public offering and concurrent private placement on October 19, 2026. The filing identifies TCGX Acquisition Corp. II as having its principal executive offices at 245 Lytton Ave., Suite 350, Palo Alto, CA 94301. The shares carry a par value of $0.0001 per share.

The filing names three reporting persons in a parent-subsidiary chain: Third Rock Ventures VI, L.P. directly owns the shares; Third Rock Ventures GP VI, L.P. is its sole general partner and may be deemed to beneficially own the same shares; and TRV GP VI, LLC is the sole general partner of Third Rock Ventures GP VI, L.P. and may likewise be deemed a beneficial owner. All three reporting persons are organized in Delaware. The principal business office for each is listed as 201 Brookline Ave, Suite 1401, Boston, MA 02215. None of the three reporting persons holds sole voting or sole dispositive power over any of the 990,000 shares; all voting and dispositive power is reported as shared among the entities.

The filing states that the percent of class was calculated based on 10,450,000 Class A ordinary shares outstanding "following the closing of the Issuer's initial public offering and concurrent private placement on October 19, 2026, as disclosed in the Issuer's final prospectus filed with the Securities and Exchange Commission pursuant to Rule 424(b)(4) on October 16, 2026." The filing further includes a certification by the reporting persons that the securities "were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer."

What Was Disclosed

Three affiliated Third Rock Ventures entities disclosed combined beneficial ownership of 990,000 Class A ordinary shares of TCGX Acquisition Corp. II, equal to approximately 9.5% of the class, stemming from the issuer's October 19, 2026, IPO close.