Cantos Fund IV

United States

Pre-Seed

About Cantos Fund IV

Cantos Fund IV is a $70M oversubscribed pre-seed and seed vehicle led by founder and GP Ian Rountree, closed in early 2026. Intentionally sized below Fund III's capacity to preserve meaningful ownership, the fund backs near-frontier deep tech across aerospace/defense, nuclear, biotech, advanced manufacturing, and compute, targeting roughly 22 investments with $1.5M-4M checks through 2026-2027. Portfolio includes Neros, Castelion, Heaviside, Astranis, Skyryse, and Venus Aerospace.

Investment Focus

Location / RegionUnited States

Funding StagePre-Seed

Industry Focus

Biotech

Deep Tech

Defense

Manufacturing

Space

Investor Signals Profile

active

Sweet Spot

Deep-tech founders building focused single-product companies in aerospace, nuclear, biotech

defense-tech

deep-tech

space

nuclear

advanced-manufacturing

Bullish Signals

Fund IV oversubscribed at $70M despite smaller sizeweb

Portfolio includes category leaders Neros, Castelion, Astranis, Skyryseweb

Concentrated ~22-company strategy preserves ownership and follow-on firepowerweb

Contrarian Signals

Narrow defense/deep-tech thesis excludes founders outside verticalsweb

Concentrated portfolio means higher bar and fewer bets per cycleweb

Founder Do's

Lead with single, laser-focused product not broad platform

Show credible path to defense or dual-use government contracts

Target check sizes $1.5M–4M for pre-seed or seed

Founder Don'ts

No broad horizontal software without deep-tech or hardware edge

Don't expect more than ~22 portfolio slots — bar is high

Key GPs & Partners

Ian Rountree

Founder / General Partner

deep-tech-specialistdefense-focusedconcentrated-portfolio

Unlock Investor Signals

€29/month for full signal access. Cancel anytime.

View Plans Browse all Signal Profiles →

Fund Overview

Fund Size$70M

Saves0

Website

Key People

Ian Rountree

Ian RountreeFounder / General Partner

Related Funds

Hamilton Lane

$615M

United States

Series A

Saas

Fund Manager:Andrew Schardt

Series A

Saas

Mainsail Partners VII

$1535M

United States

Series A

Ai Ml, Saas

Fund Manager:Gavin Turner, Jason Ayne

Series A

Ai Ml

Saas

DCVC

$700M

United States

Series A

Ai Ml, Climate Sustainability

Fund Manager:Zachary Bogue, Matthew Ocko

Series A

Ai Ml

Climate Sustainability