UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16 under the

Securities Exchange Act of 1934

For the month of January 2026

Commission File Number: 001-41709

 SEALSQ CORP

(Exact Name of Registrant as Specified in Charter)

N/A

(Translation of Registrant’s name into English)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

☒ Form 20-F ☐ Form 40-F On January 14, 2026, SEALSQ Corp ("SEALSQ") announced that it entered into a non-binding memorandum of understanding for the exclusive negotiations with the shareholders of Quobly SAS, a leading French technology company pioneering the development of silicon-based quantum computers (“QUOBLY”), for a potential multi-stage investment in QUOBLY. The proposed transaction is structured such that SEALSQ would make an initial minority investment in QUOBLY and then potentially acquire a majority interest. If the proposed transaction is completed and SEALSQ acquires a majority interest, SEALSQ will have invested approximately $200M. The proposed transaction remains subject to the negotiation and execution of definitive agreements, completion of financial, legal, technical and commercial due diligence, receipt of required corporate and regulatory approvals, and the satisfaction of other customary closing conditions.

Forward-Looking Statements

This Current Report on Form 6-K expressly or implicitly contains certain forward-looking statements concerning SEALSQ Corp and its businesses. Forward-looking statements include statements regarding our business strategy, financial performance, results of operations, market data, events or developments that we expect or anticipate will occur in the future, as well as any other statements which are not historical facts. Although we believe that the expectations reflected in such forward-looking statements are reasonable, no assurance can be given that such expectations will prove to have been correct. These statements involve known and unknown risks and are based upon a number of assumptions and estimates which are inherently subject to significant uncertainties and contingencies, many of which are beyond our control. Actual results may differ materially from those expressed or implied by such forward-looking statements. Important factors that, in our view, could cause actual results to differ materially from those discussed in the forward-looking statements include the timing of the launch of key products; SEALSQ's ability to continue beneficial transactions with material parties, including a limited number of significant customers; market demand and semiconductor industry conditions; and the risks discussed in SEALSQ's filings with the SEC. Risks and uncertainties are further described in reports filed by SEALSQ with the SEC. SEALSQ Corp is providing this Current Report on Form 6-K as of this date and does not undertake to update any forward-looking statements contained herein as a result of new information, future events or otherwise.

The information contained in this Report on Form 6-K is hereby incorporated by reference into the registration statement on Form F-3 of the Company (File No. 333-290963), as amended, and the registration statement on Form S-8 of the Company (File No. 333-287139), and into the base prospectus and any prospectus supplement outstanding under each of the foregoing registration statements, to the extent not superseded by documents or reports subsequently filed or furnished by the Company under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended.

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, thereunto duly authorized.