Air Street Capital
UnclaimedAt a Glance
- Check Size
- $100K – $5M
- Stage
- Seed, Series A
- Sectors
- AI, Biotech, Enterprise
- Founded
- 2019
- HQ
- London, UK
About Air Street Capital
Air Street Capital is a London-based venture capital firm that invests exclusively in AI-first companies in technical domains, backing them at seed and Series A across artificial intelligence, biotech and enterprise software. Nathan Benaich started the firm in 2019 and runs it as a solo general partner, an unusual structure at its scale: Fund III closed at $232 million in 2026, making it the largest single-partner venture fund in Europe, backed by US university endowments, foundations, hospitals and institutional investment platforms.
The firm leads early rounds with checks of $500,000 to $15 million and makes selective growth investments up to $25 million, concentrating on AI-first software, developer tools and infrastructure, techbio and science, and defense and security. Its portfolio includes Cradle, Faculty, Qdrant, InstaDeep and Synthace, along with Synthesia, Black Forest Labs, Wayve, Profluent, Poolside and Sereact, a list weighted toward companies with genuine research depth rather than applications layered on someone else's models.
What distinguishes Air Street is that its research output is the firm. Benaich publishes the annual State of AI Report, one of the most widely read surveys of the field, runs the Air Street Press publication and convenes research events, which together put the firm in front of technical teams before they raise. Instead of a traditional associate bench, it runs a venture fellow program whose alumni have moved into research and policy roles at Anthropic, Runway ML and quantitative finance. The combination of deep technical underwriting, a concentrated portfolio and a single decision-maker gives the firm faster conviction than committee-driven competitors in a category where timing is decisive.
Investment Thesis
“Focuses exclusively on AI-first companies in technical domains.”
Sector Focus
Investment Stage
Notable Portfolio Companies
Fund History
- Nathan Benaich founded Air Street Capital in 2019 and has since raised at least three funds, domiciled in Guernsey and filed in the United States as Reg D offerings.
- Air Street Capital II began selling in April 2022; its US filings show an indefinite offering with $3.89 million placed with American investors by August 2022, a figure that captures only the US slice of the vehicle.
- Air Street Capital III is the firm's largest: the Form D filed in August 2026 records a $232,323,232 offering fully sold, with a first sale in October 2025, and the firm announced the fund publicly in March 2026 as the largest solo general partner venture fund in Europe.
- Fund III's limited partners are US university endowments, foundations, hospitals and institutional investment platforms, with existing investors increasing their commitments.
- Check sizes run from $500,000 to $15 million at the early stage, with selective growth investments up to $25 million, concentrated in AI-first software, developer tools and infrastructure, techbio and defense and security.
SEC Fund Filings
- Vehicles filed, last 24 months
- 1
- Latest filing
Air Street Capital filed a Form D for 1 fund vehicle between Sep 30, 2024 and Sep 29, 2026.
| Fund vehicle | Source |
|---|---|
| Air Street Capital III LP | SEC Form D, filed |
A Form D is the notice a fund files with the SEC when it raises money in a private offering. Feeder funds, parallel funds and SPVs each file their own, so the count measures filing activity, not the number of flagship funds.
Source: SEC EDGAR Form D filings for pooled investment funds, original filings only (amendments excluded). Our filing data starts Jul 1, 2024. Vehicles are matched to Air Street Capital by fund name and checked against the sponsor address and named principals on each filing; offering amounts are not shown. Each “SEC Form D” link opens an EDGAR full-text search for that vehicle’s exact name, where the filing itself is listed. See every new fund filing on the Form D Radar.
Team (1)
Frequently Asked Questions
What stage does Air Street Capital invest at?
Air Street Capital primarily invests at the Seed, Series A stages. This means they focus on companies that are building their initial product and finding product-market fit.
Where is Air Street Capital located?
Air Street Capital is headquartered in London, UK. Many of their portfolio companies are also based in this region, though they invest across geographies.
What sectors does Air Street Capital focus on?
Air Street Capital focuses on investments in AI, Biotech, Enterprise. Their portfolio reflects deep expertise and networks within these sectors.
What is Air Street Capital's typical check size?
Air Street Capital's typical investment check size ranges from $100K to $5M. Actual amounts may vary based on the stage, sector, and specific opportunity.
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