Mizuho Financial Group, Inc. filed Amendment No. 1 to Schedule 13G on November 12, 2026, disclosing beneficial ownership of 953,057 common shares of Quantumsphere Acquisition Corporation as of September 30, 2026.

Key Highlights

  • Beneficial ownership: Mizuho Financial Group, Inc. reported aggregate beneficial ownership of 953,057 common shares of Quantumsphere Acquisition Corporation.
  • Percent of class: The 953,057 shares represent 8.4% of the class of common shares, according to the filing.
  • Sole voting and dispositive power: Mizuho Financial Group holds sole power to vote and to dispose of all 953,057 shares, with no shared voting or dispositive power reported.
  • Triggering event date: The date of the event requiring this filing was September 30, 2026.
  • Indirect beneficial ownership: The filing states that Mizuho Financial Group, Inc., Mizuho Bank, Ltd., and Mizuho Americas LLC "may be deemed to be indirect beneficial owners of said equity securities directly held by Mizuho Securities USA LLC," which is described as their wholly-owned subsidiary.
  • Reporting person classification: Mizuho Financial Group is classified as a Parent Holding Company (type "FI") and is organized in Japan.

Mizuho Financial Group Discloses Ownership Position in Quantumsphere Acquisition Corporation

According to the Schedule 13G Amendment No. 1 filed on November 12, 2026, Mizuho Financial Group, Inc., headquartered at 1-5-5 Otemachi, Chiyoda-ku, Tokyo, Japan, reported beneficial ownership of 953,057 common shares (CUSIP: G7387B106) of Quantumsphere Acquisition Corporation, whose principal executive offices are located at 1185 Avenue of the Americas, Suite 304, New York, NY 10036. The filing identifies the event date requiring this statement as September 30, 2026.

The filing states that Mizuho Financial Group holds sole voting power and sole dispositive power over all 953,057 shares, with zero shares subject to shared voting or shared dispositive power. The aggregate beneficial ownership represents 8.4% of the class of common shares, as disclosed in the filing. Mizuho Financial Group certified that "the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer."

The filing further notes that the shares are directly held by Mizuho Securities USA LLC, a wholly-owned subsidiary, and that Mizuho Financial Group, Inc., Mizuho Bank, Ltd., and Mizuho Americas LLC may each be deemed indirect beneficial owners of those securities. The statement was signed by Takahiro Katsura, Managing Director, Global Corporate Function Coordination Department, on November 12, 2026. Additional detail regarding the subsidiary is referenced in Exhibit A of the filing.

What Was Disclosed

Mizuho Financial Group, Inc. filed an amended Schedule 13G disclosing 953,057 common shares, equal to 8.4% of the class, in Quantumsphere Acquisition Corporation, with the triggering event dated September 30, 2026, and shares held directly through subsidiary Mizuho Securities USA LLC.