Company: GIGGU
Filing Date: 2025-10-27
Form Type: 425
Source: 0001193125-25-251693
Chunk: 7

Company: GigCapital7 Corp.
Filing Date: 2025-10-27
Form: 425
Chunk 7
---
 such statement are material. No Offer or Solicitation This Current Report on Form 8-Kdoes not constitute an offer to sell or the solicitation of an offer to buy any securities, or a solicitation of any vote or approval, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. This communication is not, and under no circumstances is to be construed as, a prospectus, an advertisement or a public offering of the securities described herein in the United States or any other jurisdiction. No offer of securities shall be made except by means of a prospectus filed with the SEC meeting the requirements of Section 10 of the Securities Act, or exemptions therefrom. Investors should consult with their counsel as to the applicable requirements for a purchaser to avail itself of any exemption under the Securities Act.

| Item 9.01 | Financial Statements and Exhibits. |

(d) Exhibits:

| Exhibit |     | Description                                                                  |
| 99.1    |     | Investor Presentation, Q4 2025                                               |
| 104     |     | Cover Page Interactive Data File (embedded within the Inline XBRL document). |

SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

| Dated: October 27, 2025 |     | GIGCAPITAL7 CORP. |     |                         |
|:------------------------|:----|:------------------|:----|:------------------------|
|                         |     | By:               |     | /s/ Dr. Avi S. Katz     |
|                         |     | Name:             |     | Dr. Avi S. Katz         |
|                         |     | Title:            |     | Chief Executive Officer |

Exhibit 99.1 CONFIDENTIAL The Future of Modular, Nuclear Energy. Always On, Always Ready. Q4 2025 Investor Presentation

CONFIDENTIAL Disclaimer This presentation (this “presentation”) is being delivered to you by Hadron Energy, Inc. (“Hadron”) and GigCapital7 Corp. (“GigCapital7”) to assist interested parties in making their own evaluation with respect to an investment in Hadron in connection with a proposed business combination between Hadron and GigCapital7 and related transactions (the “proposed business combination”). This