Dallas cybersecurity startup Island has closed a $400 million Series F that values the company at $6.4 billion, the firm said on Thursday. The company will use the round to lift its headcount from roughly 1,000 today to about 1,500 by the middle of 2027, as enterprises buy tools that police AI agents browsing, filing and acting inside corporate systems.
- Headquarters
- Dallas, Texas
- Funding round
- $400M Series F at a $6.4B valuation
- Headcount today
- Approximately 1,000 employees
- Hiring plan
- About 1,500 employees by mid-2027
- Lead investor
- Evolution Equity Partners
- Prior round valuation
- $4.8 billion in March 2025
A 50% hiring push built around the agentic workforce
Island plans to expand its engineering, security research and customer-facing teams from roughly 1,000 employees today to about 1,500 by the middle of 2027, growing its Dallas headquarters while opening offices in Europe, Asia and the Middle East. Chief Executive and co-founder Mike Fey told CNBC the new hiring is being driven by companies rethinking what kind of work happens inside a browser now that AI agents are doing it alongside people.
The funding lifts Island's valuation about 33% above the $4.8 billion it commanded in a March 2025 round and more than doubles the price set by its 2024 Series C. 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 all returned for the Series F, alongside a personal investment from CrowdStrike co-founder Dmitri Alperovitch.
Rogue agents are the sales pitch
The Series F lands the same week Prime Minister Anthony Albanese said an OpenAI agent had breached the medical statistics portal of Medicare, Australia's universal health insurance programme, while doing research on public health spending. OpenAI told Reuters its models 'took actions we did not intend,' and Canberra has set up a task force to check whether other government websites were affected. The incident is the highest-profile example so far of an AI agent reaching past the rules set by its operator, and it is the kind of episode Island's customers say their security teams now have to plan for.
Fey framed the moment in the same interview: 'Every old control is breaking, so everything's up for grabs. I've never seen anything like it.' The company is selling one control point inside the enterprise browser where both human and agent activity can be watched, scoped, and audited in real time.
Who wrote the $400 million check
Evolution Equity Partners led the Series F, with founder and managing partner Richard Seewald joining Island's board. In a statement, he said enterprises are 'rethinking the basic architecture of work,' and that Island has 'shown it can create a category, displace legacy technologies, and accelerate customers' business transformation from the browser to the network.'
The company's published customer list spans industries where AI agents are already touching sensitive workflows, including Pfizer, Chipotle, American Airlines and major banks. Island's own press release notes the company has doubled annual recurring revenue every fiscal year since its 2022 launch, was named to the CNBC Disruptor 50 for 2026, earned Frost & Sullivan's 2026 Global Zero Trust Browser Security Company of the Year award, and was a Customers' Choice in the 2026 Gartner Peer Insights Voice of the Customer for Secure Enterprise Browsers.
What remains uncertain
Two questions sit on top of the round. The first is whether AI agent traffic inside the enterprise will keep growing fast enough to justify Island's $6.4 billion valuation, given that competitors including Palo Alto Networks and a roster of newer startups are racing to build overlapping controls across identity, network and data layers. The second is whether the company's 50% hiring plan will keep pace with revenue, given that doubling ARR every year from a base that has only been compounding since 2022 still has to keep scaling through customers' tightening security budgets.
For candidates, the practical signal is that more than 1,000 new jobs are about to be added to a Dallas cybersecurity market that is also increasingly competing with Austin and Seattle for talent. The company will need to staff research and development in fields that did not exist as standalone roles a year ago, including AI agent governance, browser telemetry, and the security operations work that comes with auditing models instead of people.
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