Cantos closed an oversubscribed $70M Fund IV, founder and GP Ian Rountree confirmed, to keep leading early deep-tech rounds across aerospace, defense, nuclear, biotech, advanced manufacturing, and compute.

Key facts

• Firm: Cantos (founded 2016, San Francisco)
• Fund IV: $70M (oversubscribed; Fund III was $50M)
• Strategy: Lead pre-seed/seed with $1.5-4M checks; ~22 companies
• Notable bets: Neros (led pre-seed), Castelion, Astranis, Venus Aerospace

Why this matters

Cantos deliberately kept Fund IV small to maintain high ownership and alignment. The firm has invested in hard tech “since before it was cool,” with a defense-and-frontier portfolio now drawing broad interest.

Sources

1. Cantos $70M Fund IV (Tectonic Defense): https://www.tectonicdefense.com/first-look-cantos-raises-70m-fund-iv/
2. Cantos Fund IV close (Cryptorank, July 6, 2026): https://cryptorank.io/news/feed/cantos-raises-70-m-fund-iv