Geneva, Switzerland, June 05, 2026 -- SEALSQ Corp (“SEALSQ” or the “Company”), a subsidiary of WISeKey International Holding Ltd (NASDAQ: WKEY; SIX: WIHN) and a global leader in post-quantum semiconductor and cybersecurity solutions, today announced the acquisition of 100% of Miraex SA (“Miraex”), a developer of photonics-based quantum interconnect solutions headquartered at the EPFL Innovation Park in Ecublens, Switzerland.

As part of this strategic transaction, SEALSQ has acquired entire issued share capital of Miraex SA. The investment has been made using the Company’s Quantum Fund, SEALQUANTUM.com, an internal strategic investment initiative of SEALSQ using a dedicated allocation of our cash with the goal of accelerating the development of a fully integrated Quantum Vertical Sovereign Stack. The Quantum Fund has total approved capital resources of $ 200 million, of which over $65 million has already been deployed in several projects (including Miraex).

This milestone marks a defining step in the evolution of SEALSQ's Quantum Sovereign Vertical Stack, the Company's Root-to-Qubit architecture encompassing the full spectrum of quantum technology from quantum-resistant semiconductors to orbital space infrastructure. It also represents a pivotal acceleration of the Quantum Orbital Space Cloud (QOSC) program, SEALSQ's flagship initiative to deploy quantum-secure infrastructure across Low Earth Orbit (LEO) and beyond.

THE MISSING LINK: COMPLETING THE QUANTUM SOVEREIGN VERTICAL STACK

Miraex's acquisition closes the quantum interconnect layer of SEALSQ's Quantum Sovereign Vertical Stack, the critical bridge between quantum computing hardware and quantum communication networks. Built around a proprietary Thin Film Lithium Tantalate (TFLT) Photonic Integrated Circuit (PIC) platform, Miraex's technology enables the conversion of quantum information between microwave frequencies (the operating domain of superconducting and semiconductor spin based quantum processors) and optical frequencies (the medium of choice for quantum communication), a foundational capability without which distributed quantum architectures cannot function at scale.

Miraex's capabilities are organized across three quantum verticals that are expected to seamlessly extend SEALSQ's existing platform:

• Distributed Quantum Computing (DQC) — aimed at enabling interconnection of distributed quantum processors to achieve scalable, collective quantum computational power beyond the limits of any single device.
• Quantum Sensing — designed to deliver photonic entanglement-based distributed sensing for precision navigation, geophysics, defense, and critical infrastructure monitoring.
• Quantum Networking — building globally entangled quantum networks as the backbone of the future quantum internet, enabling end-to-end Quantum Key Distribution (QKD) at planetary scale.

REINFORCING THE QUANTUM ORBITAL SPACE CLOUD (QOSC)

Miraex's photonic technology is uniquely aligned with the demands of space-based quantum infrastructure. TFLT PICs are compact, power-efficient, and radiation-tolerant by design — attributes critical for deployment on nanosatellites, CubeSats, and the broader QOSC constellation. With this acquisition finalized, SEALSQ now commands every layer of the quantum stack required to deliver secure, space-grade quantum connectivity:

• Space-Grade Photonic Integration: Miraex's TFLT PICs meet the size, weight, power, and radiation-tolerance requirements for orbital deployment, enabling quantum-secure links between QOSC satellites and terrestrial endpoints.
• Quantum Key Distribution (QKD) at Scale: Miraex's transduction and entanglement generation capabilities provide the physical-layer substrate for satellite-based QKD, delivering information-theoretically secure communications immune to quantum adversaries.
• Distributed Orbital Sensing: Quantum sensing payloads enabled by Miraex's platform will extend QOSC's utility to precision Earth observation, sovereign navigation, and early-warning infrastructure.

THE SEALQUANTUM.COM INNOVATION LAB AND QUANTUM FUND PORTFOLIO

The Miraex acquisition is the latest transaction in a series of strategic investments and acquisitions executed through the SEALSQ Quantum Fund and the SEALQuantum.com Innovation Lab, an internal strategic investment initiative of SEALSQ using a dedicated allocation of our cash. Together, these assets form a uniquely cohesive and vertically integrated Quantum Sovereign Stack spanning semiconductors, quantum hardware, orbital infrastructure, and regulatory technology:

Taken together, these assets constitute an unparalleled end-to-end quantum value chain — from chip-level post-quantum cryptography and ASIC design, through quantum processor hardware, quantum interconnects, satellite infrastructure, industrial optimization, and sovereign regulatory compliance — all unified under a single strategic architecture accessible through SEALQuantum.com.

Carlos Moreira, Chairman & CEO, SEALSQ Corp noted, "Today's closing of the Miraex acquisition marks a watershed moment for SEALSQ and for the broader quantum ecosystem. We have spent years assembling the assets required to deliver a truly sovereign, end-to-end quantum architecture, one that begins at the silicon level with our post-quantum chips and ASICs, extends through quantum processor hardware, passes through Miraex's photonic interconnect layer, and ultimately reaches orbit through our Quantum Orbital Space Cloud. With Miraex now fully integrated, the Quantum Sovereign Vertical Stack is complete. The quantum internet is no longer a theoretical construct, for SEALSQ, it is a buildable, deployable roadmap that we can now begin to execute with customers, partners, and governments. We are grateful to the Miraex team for their vision and their extraordinary technical contributions, and we are proud to welcome them into the SEALSQ family as we focus on converting this unique strategic position into long‑term value for our shareholders."

Daniel Brau, CEO & Co-Founder, Miraex SA added, "Joining SEALSQ is the natural next step for Miraex. We built our TFLT PIC platform to be the connective tissue of the quantum ecosystem — linking quantum processors, sensors, and networks into one coherent infrastructure. SEALSQ brings the global semiconductor reach, the satellite infrastructure, and the post-quantum cryptography expertise to take that vision to planetary scale. We are proud that our technology will now form the quantum interconnect backbone of the QOSC constellation and of SEALSQ's Quantum Sovereign Vertical Stack. The era of distributed, space-secured quantum computing begins today."