Horizon3’s Series E funding round of $250 million has closed at a $2 billion valuation, more than tripling the San Francisco company’s worth in roughly 14 months and arriving at a moment when two major AI research labs disclosed that their models had breached systems outside their intended scope.
The round was oversubscribed and drew seven new investors alongside five returning backers, with NightDragon and NEA serving as co-leads, according to the company’s official press release. New names on the cap table include Acrew Capital, Blue Cloud Ventures, Demeter Group, Singapore’s EDBI, PSG, defence contractor SAIC, and Sapphire Ventures. Returning investors include Craft Ventures, Prosperity7 Ventures, Qualcomm Ventures, Ridge Ventures, and SignalFire, The Cyber Wire reported.
The previous valuation benchmark was $650 million, set in June 2025 at the Series D, according to Horizon3’s press release. The leap to $2 billion in just over a year reflects both the company’s commercial momentum and a broader investor scramble to back infrastructure that can keep pace with AI-generated threats.
What Horizon3 Series E Funding Is Actually Buying
Horizon3 was founded by Snehal Antani and Anthony Pillitiere (the co-founder’s surname is spelled ‘Pelletier’ in some coverage and ‘Pillitiere’ in others; sources conflict on the correct form). The two met while serving at Joint Special Operations Command, where resource constraints made continuous security testing difficult. They built Horizon3 to automate those repetitive assessments rather than leave them to annual human-led engagements.
The company’s NodeZero platform has logged 310,000 production security tests with zero disruptions, positioning itself as what Horizon3 calls fully autonomous penetration testing. Chief revenue officer Matt Hartley described NodeZero’s two core advantages: it can probe live systems without shutting down operations, and it scans an entire infrastructure continuously rather than the 2–3% a traditional annual test would cover.
Hartley framed the competitive threat as organisational inertia rather than rival software vendors. Most enterprises still rely on human security firms running annual assessments. What is changing is client expectations after onboarding: rather than sampling 5% of infrastructure once yearly, customers now want everything scanned monthly or weekly, with measurable evidence that their defences are actually improving.
The company approached $100 million in annual recurring revenue in the latest financial year, with 120% year-over-year growth, and expects to accelerate further. Horizon3 has spent roughly $100 million on research and development building automated systems designed to remain predictable and controllable, a design constraint Hartley described as increasingly relevant given the AI lab incidents.
AI Lab Breaches Are Reshaping the Sales Conversation
The timing of the raise is hard to separate from the backdrop. The Wall Street Journal reported that AI-related corporate anxiety, driven in part by frontier model incidents, shaped investor interest in the round. That anxiety is showing up in Horizon3’s pipeline, too.
‘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 organisations 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 organisations 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 defences against real-world exploits.’
NightDragon’s investment thesis, articulated by Managing Director Morgan Kyauk and Senior Associate Alec Kiang, frames the shift as moving from ‘episodic validation to continuous exposure management’ and from ‘playbooks and consultants to autonomous, adaptive platforms.’ The firm’s NightDragon investment commentary describes the category transition as ‘defense in depth’ giving way to ‘defense in motion.’
Horizon3 serves between 7,200 and 7,300 customers, ranging from managed service providers handling small businesses to Fortune 10 enterprises. The strategic investor mix, which now spans Singapore’s EDBI, SAIC, and Qualcomm Ventures, signals that vulnerability management is a cross-sector and cross-border problem. New offices are opening in Amsterdam (June 2026), Australia, and Singapore, alongside a partner network build-out.
Horizon3 is incorporated in Delaware as Horizon 3 AI, Inc., with an SEC registration on file, per SEC EDGAR. Tracxn puts total capital raised across all rounds at $436 million from 17 institutional investors since its first funding round in January 2020.
The company claims an addressable market running into the tens of billions of dollars. The broader cybersecurity sector was valued at $271.9 billion in 2025 and is projected to reach $663.2 billion by 2033, according to Grand View Research. Whether Horizon3 can hold its pricing power as larger vendors move into continuous testing will be the question the next 14 months answer, and the one the Series E investors are betting it can.
