Island Raises US$400M to Govern AI Agents Across the Enterprise
Island, the Dallas-based company best known for its secure enterprise browser, raised a US$400 million Series F at a US$6.4 billion post-money valuation, it announced on September 24. Evolution Equity Partners led the round, with participation from existing investors Prysm Capital, Sequoia Capital, Coatue, Cyberstarts, Insight Partners, J.P. Morgan Growth Equity Partners, Alta Park Capital, Georgian, G Squared and Squarepoint, plus a personal investment from CrowdStrike co-founder Dmitri Alperovitch. Island is led by co-founder and Chief Executive Officer Mike Fey and co-founder and Chief Technology Officer Dan Amiga, who worked together at Symantec after it acquired Amiga's previous startup, Fireglass, in 2017.
The funding supports Island's shift from browser security to what it calls an "agentic control plane," a single layer to govern both employees and AI agents across devices, browsers, applications, networks and data. The company says annual recurring revenue has doubled every year since its 2022 launch, and Calcalist reports it is now around US$200 million. Island has about 1,000 employees, up from roughly 500 last year, and counts eight of the world's ten largest banks as customers of its browser.
Market Context
The new valuation is one-third higher than the US$4.8 billion Island reached in its US$250 million Series E in March 2025, and more than double the US$3 billion it was worth in 2024. It lands in a strong week for security funding: Crunchbase News notes that Island and data security company Cyera each raised US$400 million, making cybersecurity the largest category among the week's biggest rounds.
The enterprise browser market has also become more crowded. Palo Alto Networks bought rival Talon for about US$625 million in 2023 and now sells it as Prisma Access Browser, while Google and Microsoft have added enterprise controls to Chrome and Edge, with Edge for Business included in Microsoft 365 plans at no extra cost. Moving into AI agent governance gives Island a larger market to target as its original category gets cheaper and more bundled.
The Signal
"Just like humans, agents need the right context, access, guardrails, and accountability to succeed." — Mike Fey, Co-founder and Chief Executive Officer, Island
Regional Relevance
For the United States, Island reflects how quickly AI agents are turning into a security problem for large companies. Banks, hospitals and government contractors are starting to let software agents log in, browse and move data on their own, and most security tools were built to watch people, not autonomous programs. A US$400 million bet that one control layer can supervise both points to where corporate security budgets are likely headed next.
For Dallas and Texas, Island is one of the most valuable venture-backed software companies in the region and a sign that top-tier cybersecurity companies no longer need to be based in Silicon Valley. Its model, with leadership and sales in the United States and engineering rooted in Israel's security ecosystem, is one other U.S.-Israeli startups are likely to copy.
The Other Side
Can a browser company win the AI agent layer? Agents often run through APIs and back-end systems, not just a browser window. Amiga himself says agents "cannot be governed from one" layer, which means Island must prove it can extend well beyond the browser, where Palo Alto Networks, CrowdStrike and Microsoft already have deep reach.
Will bundling squeeze prices? With Edge for Business free for many Microsoft 365 customers and Chrome's premium controls priced low, large buyers may ask why they should pay extra for a dedicated product. Island's growth depends on showing controls that the free options cannot match.
Is a US$6.4 billion valuation priced for perfection? At roughly 32 times reported recurring revenue, the valuation assumes growth keeps doubling. Any slowdown in the move from browser security to agent governance could make this round hard to justify at a future IPO.
Sources & Transparency
- Island Announces $400 Million Series F, Bringing Valuation to $6.4 Billion
- Island raises $400 million at $6.4 billion valuation as AI agents reshape enterprise security
- Island raises $400M to take its browser-security bet into AI agents
- The Week's 10 Biggest Funding Rounds: Cybersecurity, AI And Health Take The Lead
- Enterprise Browser Security 2026: Island, Talon/Prisma, Chrome, Edge Compared
- Palo Alto Networks® Announces Intent to Acquire Enterprise Browser Start-up Talon Cyber Security