WISeKey and SEALSQ Establish Quantisimo Corp. as a Special Purpose Vehicle, and Execute Letter of Intent with GigCapital8 Corp (Form 8-K)

WISeKey and SEALSQ Establish Quantisimo Corp. as a Special Purpose Vehicle, and Execute Letter of Intent with GigCapital8 Corp.

Proposed Strategic Business Public company at $575 Million Initial Enterprise Value with Significant Long Term Growth Potential Through Strategic Acquisitions

Proposed Transaction Intended to Create a Consolidated $2 Billion Trusted Quantum Pure-Play Platform Following Additional Acquisitions

Geneva, Switzerland and Palo Alto, CA, USA - June 25, 2026 - WISeKey International Holding Ltd. ("WISeKey") (SIX: WIHN; Nasdaq: WKEY), a global leader in cybersecurity and trusted digital ecosystems, and its subsidiary SEALSQ Corp. (Nasdaq: LAES), a leading developer of semiconductors, PKI, and post-quantum technologies, today announced that their jointly established special purpose vehicle, Quantisimo Corp. ("Quantisimo"), has entered into a non-binding Letter of Intent ("LOI") with GigCapital8 Corp. (Nasdaq: GIW) ("GigCapital8"), a publicly traded Private-to-Public Equity (PPE)™, also known as special purpose acquisition company (SPAC), to explore the establishment of a Nasdaq-listed strategic quantum technology platform.

The proposed transaction contemplates a business combination between Quantisimo and GigCapital8. Upon completion of the transaction, the combined company is expected to have a pre-money enterprise value of approximately $575 million, subject to customary closing conditions. The Parties intend to increase this initial valuation to reach US$2 billion through build-up consolidated acquisitions of up to an additional five quantum companies. The transaction is currently expected to close during the first quarter of 2027.

Quantisimo was created by WISeKey and SEALSQ to establish a Trusted Quantum Pure-Play platform designed to provide investors with direct exposure to the rapidly emerging quantum economy. Through a combination of proprietary technologies, strategic investments, intellectual property, and selected assets from the SealQuantum.com portfolio of companies, Quantisimo seeks to become a leading public company focused on the development, commercialization, and deployment of trusted quantum technologies.

The Executive Order 'Ushering in the Next Frontier of Quantum Innovation' signed on Monday, June 22, 2026 by President Donald J. Trump, validates Quantisimo's strategic vision. The U.S. commitment to accelerating quantum computing, sensing, networking, workforce development, and trusted supply chains is expected to expand market opportunities, increase public-private partnerships, and accelerate

the adoption of quantum technologies. Quantisimo stands to benefit from this unprecedented momentum as demand grows for quantum-enabled applications and post-quantum security solutions worldwide.

The contemplated transaction is intended to create a publicly traded platform dedicated to trusted quantum infrastructure and the broader quantum ecosystem. Quantisimo's strategy is to identify, develop, acquire, and scale technologies and businesses that are expected to benefit from the transition to the quantum era.

Unlike companies focused on a single aspect of quantum technology, Quantisimo is being developed as a Trusted Quantum Pure-Play platform, that aims to provide investors with focused exposure to the emerging quantum economy through a combination of internally developed technologies, strategic investments, partnerships, acquisitions, and intellectual property.

Quantisimo defines a Quantum Pure-Play company as one whose principal value proposition is derived from participation in the quantum technology ecosystem. Through its combination of proprietary technologies, strategic holdings, intellectual property, and investments sourced from the SealQuantum.com portfolio, Quantisimo is designed to offer investors direct and concentrated exposure to the long-term growth potential of the global quantum economy.

"We believe the world is entering the Quantum Age," said Carlos Creus Moreira, Founder and CEO of WISeKey and Chairman of SEALSQ. "Just as the Internet transformed the global economy over the past three decades, quantum technologies are expected to redefine computing, communications, security, and artificial intelligence over the coming decades. Through Quantisimo, we are creating a Trusted Quantum Pure-Play platform designed to provide investors with direct exposure to this transformational opportunity while building the trusted infrastructure required for the quantum era. We are confident that partnering with the well reputable GigCapital Global team positions us to accelerate scale, enhance market access and create long-term shareholder value as a leading quantum technology and product enterprise."

Quantisimo is expected to leverage WISeKey's internationally recognized expertise in digital trust, cybersecurity, and trusted digital ecosystems, together with SEALSQ's leadership in semiconductor technologies, cryptographic solutions, and quantum-resilient security technologies.

In connection with the proposed transaction, SEALSQ is expected to contribute, subject to the successful completion of the business combination and final board approvals, selected assets and strategic interests from its SealQuantum.com portfolio of companies. These assets include investments, technologies, intellectual property, and strategic initiatives operating across various sectors of the emerging quantum economy. The contribution is intended to strengthen Quantisimo's position as a comprehensive Trusted

Quantum Pure-Play platform and accelerate the development of an integrated ecosystem capable of capturing opportunities arising from the global adoption of quantum technologies.

Dr. Avi Katz, Founder, Executive Chairman and CEO of GigCapital Global and GigCapital8, commented: "For the 8th issued Private-to-Public Equity (PPE) by the GigCapital Global franchise we were focusing on exploring the advanced aerospace and defense vertical, and in particular leading-edge quantum platform for consolidation and taking public through our GigCapital8 platform. Quantisimo represents a unique opportunity to create a public company focused on the emerging quantum economy for the most advanced applications in both the military and commercial markets. We believe investors are increasingly seeking exposure to quantum technologies but currently have limited opportunities to participate in the sector through diversified public market vehicles. Quantisimo's Trusted Quantum Pure-Play strategy, combined with the proven technology heritage and exceptional operational leadership of WISeKey and SEALSQ, creates a compelling platform positioned to benefit from one of the most important technology transformations of the coming decades."

The parties expect to commence immediately detailed due diligence and execute definitive agreements in the coming months. The proposed transaction remains subject to the execution of definitive agreements, regulatory approvals, shareholder approvals, financing arrangements, and other customary closing conditions.

There can be no assurance that definitive agreements will be executed or that the proposed transaction will ultimately be completed.

About Quantisimo Corp.

Quantisimo Corp. is a special purpose technology vehicle established by WISeKey and SEALSQ to build a Trusted Quantum Pure-Play platform combining quantum technologies and strategic assets from the SealQuantum.com portfolio of companies. Quantisimo's mission is to provide investors with comprehensive exposure to the emerging quantum economy while supporting the development of trusted infrastructure for the quantum era.

About GigCapital8 Corp.

GigCapital8 Corp. is a Private-to-Public Equity (PPE)™ company, also known as a special purpose acquisition company (SPAC), the 8th issued entity from the GigCapital Global franchise since 2017, with a Mentor-Investor™ methodology and a mission to partner with a high technology differentiating company to forge a successful path to the public markets through a business combination. Like all other GigCapital Global Private-to-Public Equity (PPE) entities, it aims to actively partner with a deep-tech innovative company that participates in a relevant and attractive industry vertical, with exceptional leaders in order to create an industry-leading partnership that will be successful for years to come.

Private-to-Public Equity (PPE)™ and Mentor-Investor™ are trademarks of GigManagement, LLC, a member entity of GigCapital Global and affiliate of GigCapital8 Corp., used pursuant to agreement.

About SEALSQ:

SEALSQ is a leading innovator in Post-Quantum Technology hardware and software solutions. Our technology seamlessly integrates Semiconductors, PKI (Public Key Infrastructure), and Provisioning Services, with a strategic emphasis on developing state-of-the-art Quantum Resistant Cryptography and Semiconductors designed to address the urgent security challenges posed by quantum computing. As quantum computers advance, traditional cryptographic methods like RSA and Elliptic Curve Cryptography (ECC) are increasingly vulnerable.

SEALSQ is pioneering the development of Post-Quantum Semiconductors that provide robust, future-proof protection for sensitive data across a wide range of applications, including Multi-Factor Authentication tokens, Smart Energy, Medical and Healthcare Systems, Defense, IT Network Infrastructure, Automotive, and Industrial Automation and Control Systems. By embedding Post-Quantum Cryptography into our semiconductor solutions, SEALSQ ensures that organizations stay protected against quantum threats. Our products are engineered to safeguard critical systems, enhancing resilience and security across diverse industries.

For more information on our Post-Quantum Semiconductors and security solutions, please visit www.sealsq.com.

About WISeKey

WISeKey International Holding Ltd ("WISeKey", SIX: WIHN; Nasdaq: WKEY) is a global leader in cybersecurity, digital identity, and IoT solutions platform. It operates as a Swiss-based holding company through several operational subsidiaries, each dedicated to specific aspects of its technology portfolio. The subsidiaries include (i) SEALSQ Corp (Nasdaq: LAES), which focuses on semiconductors, PKI, and post-quantum technology products, (ii) WISeKey SA, which specializes in RoT and PKI solutions for secure authentication and identification in IoT, blockchain, and AI, (iii) WISeSat AG which focuses on space technology for secure satellite communication, specifically for IoT applications, (iv) WISe.ART Corp which focuses on trusted blockchain NFTs and operates the WISe.ART marketplace for secure NFT transactions, and (v) SEALCOIN AG which focuses on decentralized physical internet with DePIN technology and houses the development of the SEALCOIN platform.

Each subsidiary contributes to WISeKey's mission of securing the internet while focusing on their respective areas of research and expertise. Their technologies seamlessly integrate into the comprehensive WISeKey platform. WISeKey secures digital identity ecosystems for individuals and objects using blockchain, AI, and IoT technologies. With over 1.6 billion microchips deployed across various IoT sectors, WISeKey plays a vital role in securing the Internet of Everything. Trusted by the OISTE/WISeKey cryptographic Root of Trust, WISeKey provides secure authentication and identification for IoT, blockchain, and AI applications. The WISeKey Root of Trust ensures the integrity of online transactions

between objects and people. For more information on WISeKey's strategic direction and its subsidiary companies, please visit www.wisekey.com.

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