Horizon3 raised $250 million in a Series E round at a $2 billion valuation, announced August 3, 2026 and led by NightDragon and NEA. The round nearly triples the company's valuation from $650 million just 14 months earlier, as AI-driven attacks and defenses push automated security testing into the spotlight.
Here's the full breakdown of the raise, who backed it, and what it means for the cybersecurity market.
What is Horizon3?
Horizon3 builds an autonomous penetration testing platform that uses AI to continuously probe an organization's infrastructure for vulnerabilities — rather than the traditional model of periodic, manual pentests conducted by outside consultants. The company serves more than 7,000 organizations, including four Fortune 10 companies, giving it a customer base that spans some of the largest enterprises in the world.
The raise: $250M Series E
The headline numbers:
- Amount: $250 million
- Round: Series E
- Valuation: $2 billion
- Announced: August 3, 2026
- Lead investors: NightDragon, NEA
For context, Horizon3's prior round was a Series D at a $650 million valuation roughly 14 months earlier. Going from $650 million to $2 billion in just over a year is close to a tripling of the company's value — one of the steeper valuation climbs among cybersecurity companies in 2026.
Who invested in Horizon3?
The Series E was led by NightDragon and NEA. Additional participants included:
- SAIC
- 6 other strategic investors
The presence of SAIC, a major government-focused technology and defense contractor, alongside other unnamed strategic investors suggests Horizon3's customer base extends meaningfully into government and defense contracting, not just commercial enterprise.
What Horizon3 will do with the money
Horizon3 said the funding will go toward platform scaling and R&D. The company has reported 120% year-over-year ARR growth, a growth rate that typically requires heavy reinvestment in engineering and go-to-market capacity to sustain — which lines up with the stated use of funds.
Why it matters
- Automated security testing is proving out as a durable, well-funded category. Horizon3's near-tripling of valuation on 120% ARR growth shows investors believe continuous, AI-driven pentesting has become defensible rather than a novelty, a trend also visible in AI defense tech funding in 2026.
- AI is intensifying both sides of the security arms race. As attackers increasingly use AI to find and exploit vulnerabilities faster, Horizon3's pitch — using AI to find those same vulnerabilities first — is becoming more urgent, a dynamic echoed in AI-agent security plays like Zenity.
- Strategic investors like SAIC signal deepening ties to government and defense budgets, a customer segment that tends to bring large, sticky contracts and can help justify premium valuations for security infrastructure companies.
Source: TechCrunch — Horizon3 hits $2 billion valuation with $250M Series E as AI threats escalate
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