Item 7.01 Regulation FD Disclosure. On December 29, 2025, WISeKey International Holding AG (SIX: WIHN, NASDAQ: WKEY), a Swiss company of unlimited duration with limited liability under the laws of Switzerland, and Columbus Acquisition Corp (“ CAC”), issued a joint press release announcing the confidential submission of a draft registration statement on Form F-4 with the U. S. Securities and Exchange Commission (“ SEC”) on December 23, 2025. A copy of the press release is attached to this Current Report on Form 8-K as Exhibit 99.1 and is incorporated herein by reference. The press release shall not be deemed “filed” for any purpose, including for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “ Exchange Act”) or otherwise subject to the liabilities of that Section. The information in this Item 7.01, including Exhibit 99.1, shall not be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended (the “ Securities Act”), or the Exchange Act regardless of any general incorporation language in the filing.

Item 9.01 Financial Statements and Exhibits. (d) Exhibits The following exhibits are being filed herewith: Exhibit No. Description of Exhibits 99.1 Press Release dated December 29, 2025 ──────────────────────────────────────────────────────────────────────────────────────────────── 104 Cover Page Interactive Data File (embedded within the Inline XBRL document) SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Columbus Acquisition Corp By: /s/ Fen Zhang Name: Fen Zhang Title: Chief Executive Officer Dated: December 29, 2025