WISeKey’s WISeSat.Space Participates in FOSSA Systems Latest Financing Round, Reinforcing its European Secure Satellite Infrastructure Roadmap

Investment builds on a four-year relationship with FOSSA and supports WISeSat’s next phase of scalable, post-quantum-ready space infrastructure

Geneva, Switzerland – June 25, 2026 – WISeKey International Holding Ltd. ("WISeKey") ((SIX: WIHN, NASDAQ:WKEY), a global leader in cybersecurity, digital identity and IoT, today announced that its WISeSat.Space Corp. subsidiary ("WISeSat") has participated in the latest financing round of FOSSA Systems, S.L. ("FOSSA"), a Spain-based aerospace and defence company specialising in small-satellite development, launch and operations for Low Earth Orbit communications and radio-frequency applications.

The investment strengthens a strategic relationship that began in 2021, when WISeKey first partnered with FOSSA to support the development of small-satellite platforms for secure IoT communications from Low Earth Orbit. Since then, FOSSA has contributed to WISeSat’s early satellite-related activities and pilot missions, helping establish technical learning, flight heritage and operational experience that support WISeSat’s planned transition toward larger and more capable satellite infrastructure.

A Strategic Moment for European Secure Space Infrastructure

The investment comes at a time when Europe is placing increased emphasis on resilient, sovereign and secure space capabilities. Across the public and private sectors, space infrastructure is increasingly seen as a strategic layer for communications resilience, data security, defence readiness, critical infrastructure protection and technological autonomy.

Against this backdrop, WISeSat’s continued investment in its FOSSA relationship reinforces its objective to build a European-rooted secure satellite infrastructure platform. WISeSat’s roadmap is focused on providing satellite capacity, orbital infrastructure and related ground-segment capabilities for secure communications, IoT connectivity and future post-quantum and quantum-secure use cases.

Expanding on Four Years of Collaboration

WISeSat has built an early satellite access base across 25 launched LEO satellites through partner-operated missions, with access to 8 satellites currently in operation. These missions have contributed to WISeSat’s pilot testing, technical validation and flight-heritage programme as the company prepares its next phase of satellite infrastructure.

This latest investment reaffirms WISeSat’s confidence in FOSSA’s small-satellite capabilities and strengthens the industrial relationship between the two companies. WISeSat expects this relationship to remain relevant as it evaluates next-generation satellite platforms, future launch requirements, payload integration, ground-segment architecture and mission operations for secure space-based infrastructure.

Ecosystem Integration with WISeKey and SEALSQ

WISeSat operates within WISeKey’s ecosystem, which combines cybersecurity, digital identity, semiconductors, post-quantum technology and trusted infrastructure. Within that ecosystem, SEALSQ Corp. ("SEALSQ") (NASDAQ:LAES), a subsidiary of WISeKey, focuses on semiconductors, public key infrastructure and post-quantum technology products.

SEALSQ has also established its Quantum Fund, SEALQUANTUM.COM, to support the development of sovereign quantum and post-quantum technology capabilities. While WISeSat’s investment in FOSSA is a WISeSat strategic investment and does not by itself make FOSSA a SEALSQ Quantum Fund portfolio company, it is aligned with the broader WISeKey and SEALSQ objective of developing secure, trusted and quantum-resilient infrastructure across the semiconductor, cybersecurity and space layers.

WISeSat’s role in this ecosystem is focused on satellite infrastructure. SEALSQ’s planned Quantum Spatial Orbital Cloud, or QSOC, is expected to be a SEALSQ-owned quantum and quantum-resilient initiative intended to use WISeSat satellite capacity and infrastructure as part of a future orbital layer for quantum key distribution ("QKD"), quantum random number generation ("QRNG"), post-quantum identity and other secure communications services. Any such use would remain subject to definitive agreements, technical validation, financing, regulatory approvals, launch cadence and customer demand.

Carlos Moreira, Founder and CEO of WISeKey, said: "FOSSA has been a key industrial partner in in the early development of WISeSat’s satellite capabilities, providing critical technical expertise and flight heritage as we established our initial presence in low Earth orbit. This investment reflects our confidence in FOSSA’s platform and our shared vision for scalable, secure satellite infrastructure. As we transition from pilot missions to a more advanced and integrated orbital architecture, strengthening this relationship is an important step in de-risking execution and accelerating our roadmap."

Mr. Moreira continued, "At the same time, we see a clear and growing market opportunity as Europe prioritizes sovereign, resilient and secure space-based communications. By combining WISeSat’s satellite infrastructure roadmap with WISeKey’s Root of Trust and SEALSQ’s post-quantum semiconductor capabilities, we are building the foundations for a trusted European space-technology platform designed for the next era of secure communications. We believe this integrated approach positions us to capture long-term value in secure communications, IoT connectivity and future quantum-resilient applications."

Julián Fernández, CEO of FOSSA Systems, said: "FOSSA and WISeSat have worked together since the early stages of WISeSat’s satellite roadmap. We welcome WISeSat’s continued support as part of our Series B financing round and look forward to exploring further cooperation around small-satellite infrastructure, secure communications and future mission capabilities."

About FOSSA Systems

FOSSA Systems specializes in satellite-based communications and intelligence solutions for industrial and defense applications. The company integrates the design and operation of satellites, ground stations, and IoT devices, enabling connectivity from low Earth orbit (LEO). Since 2022, it has launched 25 satellites and is deploying a constellation of 140 to provide global IoT coverage. Its solutions are used across sectors such as energy, utilities, oil & gas, logistics, and critical infrastructure, as well as in security and defense. Founded in 2020 by Julián Fernández and Vicente González, the company works with international clients including Microsoft and European ministries of defense. It is headquartered in Madrid, with offices in Lisbon and Tokyo.

Learn more at FOSSA Systems

About WISeSat.Space

WISeSat develops, procures and operates small-satellite infrastructure, rights-of-use arrangements and associated ground-segment capabilities in Low Earth Orbit. As the space-infrastructure platform supporting SEALSQ’s planned QSOC roadmap, WISeSat is expected to provide satellite capacity and orbital infrastructure that SEALSQ may use for post-quantum security and quantum-enabled services, subject to definitive agreements, technical validation, financing, regulatory approvals, launch cadence and customer demand.

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.

Forward-Looking Statements

This communication contains forward-looking statements concerning WISeKey International Holding Ltd and/or its subsidiaries (collectively, "WISeKey," "our" or "us") and its businesses. Forward-looking statements can be identified by terms such as "anticipate," "believe," "estimate," "expect," "intend," "may," "plan," "project," "will," and similar expressions. These statements involve known and unknown risks, uncertainties and other factors that could cause WISeKey’s actual results, financial condition, performance or achievements to differ materially from any future results, performance or achievements expressed or implied by such forward-looking statements. These factors include: our ability to convert our pipeline into actual sales; the ability to realize WISeKey’s anticipated growth strategies and profitability; the development of post-quantum cryptography products and the potential market for such products; WISeKey’s plans for global customer base expansion; the expansion of the WISeSat project and the QSOC initiative; the timing and expected revenues from the commercial deployment of the QS7001 quantum-resistant semiconductor; the sufficiency of cash to meet liquidity needs; WISeKey’s ability to attract and retain customers; changes in economic conditions; market demand and semiconductor industry conditions; and the risks discussed in WISeKey’s filings with the SEC. WISeKey is providing this communication as of this date and does not undertake to update any forward-looking statements as a result of new information, future events or otherwise.

Statements regarding our business pipeline are based on management's current estimates of potential revenue opportunities and do not represent backlog or contracted revenue. Pipeline conversion is subject to numerous factors including customer validation, technical integration requirements, certification timelines, and market conditions. There can be no assurance that pipeline opportunities will convert to actual sales or that such conversion will occur within anticipated timeframes.

This press release does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, and it does not constitute an offering prospectus within the meaning of the Swiss Financial Services Act ("FinSA"), the FinSA’s predecessor legislation or advertising within the meaning of the FinSA. Investors must rely on their own evaluation of WISeKey and its securities, including the merits and risks involved. Nothing contained herein is, or shall be relied on as, a promise or representation as to the future performance of WISeKey. Given the risks and uncertainties described herein, you should not place undue reliance on forward-looking statements as a prediction of actual results.

Press and Investor Contacts

WISeKey International Holding Ltd

Company Contact: Carlos Moreira

Chairman & CEO

Tel: +41 22 594 3000

info@wisekey.com

WISeKey Investor Relations (US)

The Equity Group Inc.

Lena Cati

Tel: +1 212 836-9611

lena.cati@theequitygroup.com