Island raises $400m at $6.4bn to sell enterprises a control plane for AI agents

Island's own release, dated 24 September, states a $400 million Series F at a $6.4 billion valuation led by Evolution Equity Partners, with Prysm Capital, Sequoia Capital, Coatue Management, Cyberstarts, Insight Partners, J.P. Morgan Growth Equity Partners, Alta Park Capital, Georgian, G Squared and Squarepoint named as participants. That is the confirmed spine of the story: a valuation and a cash figure, from the company that raised the money.

The valuation step is worth stating precisely, because a secondary account got it wrong. Island's previous round, per its own March 2025 release, was a $250 million Series E at $4.8 billion led by Coatue, bringing total outside investment to approximately $730 million. So the move is $4.8bn to $6.4bn, about a third higher, and total outside money now sits near $1.13 billion. One write-up implied a prior valuation of $4.6 billion by working backwards from a stated increase; that does not match Island's own prior figure and is not used here.

On growth, the company says it has doubled annual recurring revenue every fiscal year since its 2022 launch. No base number is given, so the multiple is unanchored — doubling four times from an undisclosed figure tells a reader nothing about scale. It is the company's own statement about its own revenue and is recorded as claimed.

What is substantively new is the positioning. Island is raising against agent governance rather than browser security: the release describes identity governance, access controls, guardrails, data boundaries, human approvals, cost governance and audit trails for AI deployment at scale. That is a datapoint about where enterprise security budget is going, and it is corroborated by the identity of the money — a cyber-specialist lead alongside crossover and growth funds.

• Confirmed $400m Series F at a $6.4bn valuation, led by Evolution Equity Partners. Island press release
• Confirmed The prior round was a $250m Series E at $4.8bn in March 2025, taking outside investment to about $730m at that point. Island press release, March 2025
• Claimed Island says it has doubled annual recurring revenue every fiscal year since its 2022 launch. No base figure is disclosed. Island press release