Estonia’s Skeleton becomes a $1 billion unicorn as Siemens backs US expansion
Estonian energy-storage company Skeleton Technologies has joined the ranks of Europe’s unicorns after a new investment led by German industrial group Siemens lifted its valuation above $1 billion. The deal also gives Skeleton an exclusive global sales partner for its technology in the rapidly expanding AI data-centre market.
The investment, announced on 14 October, exceeds $100 million, according to information provided by Skeleton to Bloomberg. CEO and co-founder Taavi Madiberk confirmed that the transaction had pushed the Tallinn-based company’s valuation above the $1 billion threshold. The exact valuation and Siemens’ individual contribution to the funding round were not disclosed.
The agreement goes beyond financing. Siemens has secured exclusive global rights to sell and scale Skeleton’s high-power energy-storage systems in the data-centre sector, integrating the Estonian company’s supercapacitor technology into its electrical infrastructure portfolio. According to Siemens, it already works with nine of the world’s ten largest data-centre providers.
Skeleton’s technology addresses one of the emerging constraints on AI infrastructure: sudden, large fluctuations in electricity demand as thousands of processors switch between computing tasks. Its supercapacitor systems can absorb these rapid changes, reducing stress on electrical equipment and helping data-centre operators make better use of existing power capacity.
The new capital will support Skeleton’s expansion in the United States, including domestic manufacturing of supercapacitor cells and research and development in Silicon Valley. The company plans to invest more than $200 million in US operations and R&D, extending its industrial footprint beyond existing production facilities in Germany and Finland.
The investment also marks another stage in a partnership that began in 2022. Siemens became a Skeleton investor in 2023 and has supported the automation of its German manufacturing operations. Skeleton is also preparing for a potential US stock-market listing in 2027.
Separately, Estonian industrial group Harju Elekter has agreed to sell part of its Skeleton shareholding to Siemens International Holding for €5.7 million. Harju Elekter, which first invested in Skeleton in 2015, will remain a shareholder. The sale is expected to close before the end of 2026.
The combination of new capital, American manufacturing plans and Siemens’ global sales network gives Skeleton a route from European energy-storage manufacturing into the infrastructure supply chains of the world’s largest AI data-centre operators.
Sources: Siemens, 14 October 2026 · Bloomberg, 14 October 2026 · Tech.eu, 14 October 2026 · Harju Elekter, 14 October 2026