Horizon3 triples to $2B running AI pentests
Horizon3's $250M Series E values it above $2 billion after its autonomous NodeZero platform ran 310,000 live-network attack simulations.
Horizon3 raised $250 million in a Series E co-led by existing investors NightDragon and NEA, valuing the company above $2 billion, roughly triple its $650 million Series D valuation from just over a year ago. The round drew seven new investors alongside five returning backers. Horizon3’s platform, NodeZero, autonomously tests a customer’s own production network for weaknesses, chaining misconfigurations, weak credentials and identity gaps into a working attack path; the company says it has safely run 310,000 such tests inside live environments, protecting more than 7,000 organizations including four Fortune 10 companies, and grew annual recurring revenue 120% year over year.
The new capital goes toward expanding sales and channel operations, plus new offices in Singapore and Australia. It’s the third AI-agent-security round to close this week, alongside Zenity’s $125M raise and Obsidian Security’s $85M round, and the acquisition wave that preceded it, including Cyera’s purchase of Oasis Security.
What it means for operators
Horizon3’s framing, “AI vs. AI,” is the honest version of where offensive security is heading: the same agentic techniques that let an AI system autonomously chain a network breach are now sold back to defenders as a continuous, automated pentest instead of an annual manual one. If your security budget still treats penetration testing as a once-a-year checkbox, this round and its valuation are a signal that continuous, AI-run testing is becoming the market’s actual expectation, not a premium add-on.