Island raises $400M to take its browser-security bet into AI agents

Why it matters

Island's founders turned browser security into a $6.4 billion financing story. Their next test is whether customers will extend that trust from the browser to controls over AI agents across enterprise systems.

Island raised $400 million in a Series F at a $6.4 billion valuation on September 24th, backing co-founders Dan Amiga and Mike Fey as they expand beyond the enterprise browser toward security controls for AI agents. Island's announcement gives the round details. Reuters reported that Evolution Equity Partners led the round, with existing investors Prysm Capital, Sequoia Capital, Coatue Management, Cyberstarts, Insight Partners and J.P. Morgan Growth Equity Partners participating.

The founders' case starts with a familiar piece of enterprise infrastructure that security teams have often treated as someone else's product: the browser. Island's original pitch was to build security, access and data controls into the software employees already use to reach company systems. Now Amiga, Island's CTO, is arguing that a browser is a starting point for controlling a larger problem: people and software agents acting across company applications and data.

That shift builds on a founder pairing forged in an earlier cybersecurity deal. Amiga founded Fireglass, a secure-browsing startup, before Symantec acquired it in 2017. Fey, then Symantec's president, was on the acquiring side. Amiga and Fey later co-founded Island, with Fey taking the CEO role and Amiga leading technology. In a September interview with Calcalist, Amiga described their complementary strengths: Fey brought experience in sales, marketing and managing a US-based operation; Amiga said he preferred building products.

From browser controls to agent governance

Island's Series F announcement describes the company as an "agentic control plane" for enterprises. Its stated goal is to apply one policy system and audit trail across browsers, endpoints, applications, networks and data, including when an AI agent is doing the work. That is a bigger remit than securing a browser, and it gives Island a way to pitch its existing access and data controls as infrastructure for companies adopting agents.

The appeal is straightforward: an agent that can interact with corporate applications may also reach sensitive information or take actions under an employee's authority. Island says its approach brings identity, access rules, data boundaries, approvals and auditability together. Those are company claims about its product and its intended role; the funding announcement does not establish how many customers are using the broader agent-control offering or how much revenue it contributes.

The founders have already made the bet that enterprises would consider replacing or supplementing familiar browsers with a purpose-built work environment. Island emerged from stealth in February 2022. In March 2025, it announced a $250 million Series E at a $4.8 billion valuation, led by Coatue Management. The new $6.4 billion valuation is one-third higher than that previous mark. A valuation records the terms investors accepted for a private financing; it does not by itself show whether the expanded product strategy will translate into durable adoption.

A large round, and a broader claim

Island's company announcement says the business employs 1,000 people and has doubled annual recurring revenue every fiscal year since its 2022 launch. Those are company-reported figures. Separately, Amiga told Calcalist earlier in September that Island had about $200 million in revenue and was growing roughly 100% annually. The metrics come from different descriptions of performance, and neither announcement supplies audited financials or detail on revenue mix.

The Series F's investor roster also extends beyond the names in Reuters' report. Island's release lists existing investors Prysm Capital, Sequoia Capital, Coatue Management, Cyberstarts, Insight Partners, J.P. Morgan Growth Equity Partners, Alta Park Capital, Georgian, G Squared and Squarepoint, plus another personal investment from cybersecurity entrepreneur Dmitri Alperovitch. Evolution Equity Partners led the round. The roster shows continued backing from prior investors alongside the new lead, while the company's own description ties the financing to expansion around AI agents.

That ambition puts Island's next chapter in a different competitive frame. The enterprise browser was a direct challenge to the assumption that companies should accept consumer browsers and layer security tools around them. Agent governance reaches into controls already managed across identity, endpoint, network and data-security products. Island's pitch is that those layers need a shared view of what people and agents are doing. Whether customers buy that as a unified platform, or keep assembling controls from incumbent vendors, is the commercial test behind the new valuation.

Amiga's earlier Fireglass exit gave him a firsthand view of browser security as an acquisition target. Island's financing now supports a longer wager: build a standalone company around the browser, then extend that foothold into the rest of enterprise work. Fey's experience running large security businesses and Amiga's repeated focus on product creation are central to that strategy. The $400 million gives them more room to pursue it; customer adoption of the broader control layer will determine whether it becomes more than an expanded description of the original browser business.