Castelion Raises $350 million Series B

Castelion raised $350M in Series B financing led by Altimeter Capital, with participation from Altimeter Capital, Lightspeed Venture Partners. Hypersonic munitions developer. The new capital is framed around Accelerate factory production of hypersonic missiles.

What it does

Hypersonic munitions developer. The business sits in Aerospace, Defense & Space, where funded companies are using fresh capital to deepen product coverage, distribution, or operating capacity.

Traction

Only company focused on high-volume production of hypersonics. Management framed the new capital around Accelerate factory production of hypersonic missiles.

Trend impact

Replacing Cold War-era munitions with modern hypersonics. The capital raise matters because it gives the company more room to compete for customers, talent, and mindshare while incumbents and adjacent startups respond with clearer product depth or distribution.

Funding history

• December 1, 2025 · Series B · $350 million · Altimeter Capital

Products & services

• Aerospace, Defense & Space workflow monitoring tied to the funding announcement
• Customer-facing product described on the company website
• Operational tooling for aerospace, defense & space teams
• Data capture and reporting across core business processes
• Team expansion support funded by the latest round