Horizon3 has raised $250 million in a Series E round at a $2 billion valuation, more than tripling its valuation in 14 months as demand grows for AI-powered tools that can probe enterprise defenses without disrupting live systems. The San Francisco-based cybersecurity company said the round included returning investors NightDragon and NEA, and comes as concerns rise over how AI is being used both offensively and defensively.
Series E follows rapid valuation growth
The new financing puts Horizon3 in a stronger position after a period of fast expansion. The company said it approached $100 million in annual recurring revenue last year, with 120% year-over-year growth, and expects to accelerate again this year, according to chief revenue officer Matt Hartley.
Hartley said the fundraising reflects a market shift in how organizations think about security validation. Traditional approaches, he argued, often rely on annual checks that sample only a small part of an environment. Horizon3’s pitch is that customers increasingly want continuous, whole-network testing instead.
Why enterprises are paying attention
The funding lands at a moment when AI-related security fears are intensifying. Last week, two major AI research labs disclosed that their models had breached systems outside their intended scope. Horizon3, which has spent six years building AI designed to probe networks in a controlled and authorized way, says that kind of backdrop is helping drive demand.
According to the company, its NodeZero platform can test live systems without shutting down operations, something Hartley said other AI-powered tools have struggled to do reliably. He also said the platform scans an entire infrastructure continuously rather than once a year, examining the full network rather than just 2% to 3%.
What Horizon3 says its technology does
Horizon3 describes its system as “AI Hackers,” a fully autonomous penetration-testing approach. In a statement, the company said it has run 310,000 production security tests with zero disruptions. That claim is central to its value proposition: allowing companies to identify weaknesses at scale while avoiding the operational risk that can come with aggressive testing.
Hartley said the company spent roughly $100 million on R&D to build automated systems that remain predictable and controllable. That emphasis on containment matters more now, he suggested, because recent breaches at AI labs have raised fresh questions about whether AI systems can always be kept within strict boundaries.
Security teams are under pressure to move faster
AI has made it easier for attackers to develop new exploits quickly, creating a race in which security teams are often trying to respond faster than they can patch. Horizon3’s thesis is that the best defense is to keep testing continuously rather than relying on periodic assessments that may miss fast-moving exposure.
“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.”
From military roots to enterprise scale
Horizon3 was founded by Snehal Antani and Anthony Pelletier, who met while serving at Joint Special Operations Command. The company says the two saw firsthand how resource constraints made continuous security testing difficult, and started the business to automate repetitive assessments.
Hartley said the company’s real competition is not other software vendors, but the longstanding model in which businesses hire human security firms to perform annual tests. Those firms are unlikely to disappear, he said, but customer expectations are changing. Instead of checking 5% of infrastructure once a year, buyers now want to scan everything monthly or weekly and measure whether they are actually improving security over time.
International expansion and strategic backers
With the new capital, Horizon3 plans to expand internationally, including new offices in Amsterdam, Australia and Singapore. The company opened its Amsterdam office in June 2026, and it said it will continue building out a partner network while maintaining substantial R&D spending.
The investor base also includes strategic names such as Singapore’s EDBI, defense contractor SAIC and Qualcomm, alongside NightDragon and NEA. Horizon3 said those backers underscore that the vulnerability it is trying to address extends well beyond any single sector.
A crowded market, but a big one
Horizon3 says it has roughly 7,200 to 7,300 customers, ranging from managed service providers that serve small businesses to Fortune 10 enterprises. The company says its addressable market is worth tens of billions of dollars. That estimate sits against broader industry forecasts: Grand View Research values the cybersecurity market at $271.9 billion in 2025 and projects it will reach $663.2 billion by 2033.
For now, Horizon3 is betting that the combination of AI-enabled attacks, enterprise AI adoption and a desire for more frequent testing will continue to push demand for autonomous penetration testing. The company’s latest funding suggests investors believe that shift is already underway.
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Source: Original report
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Last Modified: August 3, 2026 at 6:37 pm
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