Funding round
Castelion Series B
Castelion, which works in defense technology research and development in Torrance, raised $350M in a Series B round announced on 5 Dec 2025, led by Altimeter and Lightspeed Venture Partners. 12 firms took part. It is Castelion's fourth venture round on record; the one before was a Series A in Jan 2025.
$350M
Amount raised
Not disclosed
Post-money valuation
12
Investors
2 leads
Valuation
What this round says about the price
Castelion did not disclose a valuation in this round. It came 11 months after Castelion's Series A. It is 24% of the $1.44B Castelion has raised in the venture rounds on record. Castelion raised again 8 months later: a Series C round of $1.00B in Aug 2026, at $13.00B post-money.
Castelion's funding rounds
Castelion has 5 venture rounds on record. This one is highlighted.
- Pre-seed 1 Apr 2023, led by Lavrock Ventures $5.4M
- Seed 5 Oct 2023, led by Andreessen Horowitz and Lavrock Ventures $14M
- Series A 29 Jan 2025, led by Lightspeed Venture Partners $70M
- Series B this round 5 Dec 2025, led by Altimeter and Lightspeed Venture Partners $350M
- Series C 19 Aug 2026, led by J.P. MorganChase’s Strategic Investment Group, Andreessen Horowitz and Carlyle $1.00B$13.00B post-money
Investors
Who put money in
Altimeter and Lightspeed Venture Partners led the round with 10 other firms.
Lead investors
- Altimeter backs 67 venture-backed companies new investor
- Lightspeed Venture Partners backs 454 venture-backed companies new investor
Also in the round
- backs 22 venture-backed companies new investor
- Andreessen Horowitz backs 722 venture-backed companies new investor
- General Catalyst backs 574 venture-backed companies new investor
- backs 24 venture-backed companies new investor
- backs 9 venture-backed companies new investor
- backs 36 venture-backed companies new investor
- backs 28 venture-backed companies new investor
- backs 42 venture-backed companies new investor
- backs 6 venture-backed companies new investor
- Interlagos new investor
Use of proceeds
What the money is for
According to the announcement, the money goes to product development, scaling operations and working capital.
- Product development
- Scaling operations
- Working capital
Comparable rounds
How it compares
34 Series B rounds in Aerospace and Defence within a year either side disclosed an amount; the median was $34M, and this round was 10 times the median. The closest in time, other companies' Series B rounds in Aerospace and Defence:
| Company | Announced | Amount | Post-money | Led by |
|---|---|---|---|---|
| Aerospace and Defence | 1 Dec 2025 | $6.0M | $215M | AVCF1 |
| Aerospace and Defence | 11 Nov 2025 | $75M | not disclosed | Sequoia Capital |
| Aerospace and Defence | 7 Nov 2025 | $18M | not disclosed | not named |
| Aerospace and Defence | 8 Oct 2025 | $20M | $100M | Leonardo DRS and Korea Robot Manufacturing |
| Performance Drone Works Aerospace and Defence | 25 Mar 2026 | $110M | not disclosed | Ondas |
| Aerospace and Defence | 13 Mar 2026 | $20M | not disclosed | Stride Capital Group |
| Aerospace and Defence | 26 Aug 2025 | $110M | not disclosed | Noshaq |
| Aerospace and Defence | 7 Apr 2026 | $100M | not disclosed | Point72 Ventures and Activate Capital |
Sources
Where this comes from
Reported by 4 sources.
Questions
Frequently asked
How much did Castelion raise in its Series B round?
Castelion raised $350M in its Series B round, announced in Dec 2025.
Who led Castelion's Series B round?
Altimeter and Lightspeed Venture Partners led it, with Lavrock Ventures, Andreessen Horowitz, General Catalyst, First In and Space VC and 5 more.
What was Castelion's valuation at the Series B round?
It was not disclosed.
How does it compare with other Series B rounds in Aerospace and Defence?
34 Series B rounds in Aerospace and Defence within a year either side disclosed an amount; the median was $34M, and this round was 10 times the median.
Did Castelion raise again after this round?
Yes: a Series C round in Aug 2026 of $1.00B at $13.00B post-money.