Horizon3, a San Francisco-based cybersecurity startup, has raised $250 million in a Series E round at a $2 billion valuation, more than tripling its valuation in 14 months. The round was backed by returning investors NightDragon and NEA, with strategic participation from Singapore’s EDBI, defense contractor SAIC, and Qualcomm. The funding arrives as two major AI research labs disclosed last week that their models had breached systems outside their intended scope, underscoring the growing risk of AI-driven attacks.
Horizon3 has spent six years building AI specifically designed to probe networks for vulnerabilities in a controlled, authorized manner. The company’s NodeZero platform has run 310,000 production security tests with zero disruptions, according to a company statement, establishing what it calls “AI Hackers” — fully autonomous penetration testing.
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Why enterprises are shifting to continuous testing
Matt Hartley, Horizon3’s chief revenue officer, said the NodeZero platform has two core strengths: it can test live systems without shutting down operations, a capability other AI-powered tools have struggled to deliver reliably, and it scans an entire infrastructure continuously rather than once a year, examining the full network rather than just 2-3%.
The company approached $100 million in annual recurring revenue last year with 120% year-over-year growth, and expects to accelerate growth this year, Hartley said. The demand is driven by a fundamental shift in how enterprises approach security testing. Most companies hire human security firms to run annual tests, and those won’t disappear, Hartley said. What’s changing is what clients demand after signing up: Instead of sampling 5% of infrastructure once yearly, they now want to scan everything monthly or weekly, tracking whether they’re actually getting safer.
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AI tools have made it easier for attackers to develop new exploits quickly, forcing security teams to handle threats faster than they can fix them. Horizon3 spent roughly $100 million in R&D building automated systems designed to stay predictable and controllable, Hartley said.
AI’s double-edged sword in security
The recent breaches at AI labs have raised questions about whether any AI system can truly remain contained. “It’s also making people a lot more careful about how they deploy AI,” Hartley said. “We’re getting a lot of questions today around: can you detect AI? Of course we can. But I think a lot of organizations that rushed to deploy AI across the enterprise are now thinking twice about the ramifications of those deployments; what if my own security team gets too aggressive, could there be unintended consequences? So a lot of organizations are moving into what I’d call a bold new world, which is exactly why you need consistent, predictable testing from a company like Horizon3, to know how to strengthen your own defenses against real-world exploits.”
The real competition isn’t other software vendors; it’s the existing model, according to Hartley. Traditional security firms conduct annual or quarterly tests, but the gap between those assessments leaves systems exposed for months. Horizon3’s approach aims to close that gap.
Expansion plans and market outlook
With the funding, Horizon3 is expanding internationally, including new offices in Amsterdam (opened in June 2026), Australia, and Singapore, while building a partner network and maintaining substantial R&D spending. The company has roughly 7,200 to 7,300 customers, ranging from managed service providers serving small businesses to Fortune 10 enterprises.
The company claims an addressable market of tens of billions of dollars, a figure that aligns with industry estimates of the broader cybersecurity market, valued at $271.9 billion in 2025 and projected to reach $663.2 billion by 2033, according to Grand View Research.
Horizon3’s founders, Snehal Antani and Anthony Pelletier, met while serving at Joint Special Operations Command, where they saw firsthand how resource constraints made continuous security testing difficult. They founded Horizon3 to automate those repetitive assessments.
The strategic investors — including Singapore’s EDBI, defense contractor SAIC, and Qualcomm — signal that the vulnerability Horizon3 addresses extends well beyond any single sector. As AI-driven attacks accelerate, enterprises are rushing to stress-test their defenses at scale, a gap that traditional security vendors have largely left unfilled.
Disclaimer: This article is for informational purposes only and does not constitute financial advice. The cybersecurity market is volatile and subject to rapid change; readers should conduct their own research before making investment decisions.
