SCHEDULE 13G/A

QUANTUMSPHERE ACQUISITION CO

Class A ordinary shares, par value $0.0001 per share · CUSIP: G7387B106

Event date: 2026-09-30

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• W. R. Berkley Corporation

  Shares: 1,081,561.00 · Class: 9.5%

• Berkley Insurance Company

  Shares: 1,081,561.00 · Class: 9.5%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.