Horizon3 raises $250M Series E at $2B+ for autonomous pentesting

The round was announced August 3, 2026, and was oversubscribed. NightDragon and NEA, both prior backers, co-led it, with seven new investors and five returning ones. Total funding to date stands at $428.5 million. The raise follows 120% annual recurring revenue growth and a customer base above 6,500 organizations, including the NSA, CISA and four Fortune 10 enterprises. The money is earmarked for sales expansion and entry into Australia and Singapore. Go-to-market plans also include MSP and telco partnerships, plus more R&D aimed at AI-driven threats. NodeZero differs from scanners and scripted simulation tools. It performs live exploitation in customer environments with no human intervention during tests. It then gives fix guidance and retests to confirm the vulnerabilities are closed. It can also deploy decoys meant to expose AI-driven intruders already inside a network. For AI founders, the notable point is where the moat sits. Horizon3's data advantage exists only because thousands of companies let its software attack their production systems. Proprietary outcome data from real deployments, collected over years, is what investors are pricing here, not model benchmarks. The same logic applies to any AI product that runs inside customer environments: trust, and the data it generates, compounds into a lead that newer entrants find hard to copy.