Cybersecurity startup Armadin has raised $255.5 million in a Series B round co-led by Andreessen Horowitz and Accel, pushing its valuation past $2.5 billion just seven months after its public launch in Palo Alto, California, according to company announcements on October 1, 2026.
The financing brings Armadin’s total funding to $445 million following a $190 million Series A in March.
Founded by Mandiant creator Kevin Mandia, the company deploys automated agent swarms to run continuous vulnerability tests for enterprise and government clients.
Kevin Mandia Builds Armadin
Mandia launched Armadin to address what he views as a dangerous asymmetry in modern digital defense. The startup operates on the thesis that frontier AI models are drastically compressing the timeline between public vulnerability disclosures and working exploits.
Mandia established Mandiant, which was acquired by FireEye for $1 billion in 2014 before Alphabet Inc. acquired the breach investigation firm for $5.4 billion in 2022. He also co-founded Ballistic Ventures, a cybersecurity-focused startup fund that backed Armadin’s newly closed round. Alongside Mandia as chief executive officer, the company’s leadership team includes chief technology officer Travis Lanham, chief offensive security officer Evan Peña, and chief architect David Slater.
“Offense is uniquely advantaged right now, AI lets an attacker find and chain weaknesses faster than any human team can respond.”
Kevin Mandia, CEO of Armadin
Traditional vulnerability scanners score each finding in isolation, while manual penetration testing happens only periodically. By contrast, Armadin deploys thousands of autonomous agents inside a secure sandbox to map out internal systems and simulate coordinated attacks.
Armadin Executes Autonomous AI Hyperattacks
Rather than running single-point checks, these agents connect individually low-severity weaknesses into validated kill chains.
Every action taken during these evaluations passes through a control layer overseen by a safety model trained using feedback from human security experts.
“Against agentic adversaries, the best defense is a great offense powered by AI. That was our conviction when we led Armadin’s Series A, and it’s even more pressing today.”
Ping Li, Partner at Accel
Investors Back Armadin Series B
The October 1, 2026 round lifted the startup’s valuation above $2.5bn, reflecting heavy institutional backing from Silicon Valley venture capital firms. Andreessen Horowitz and Accel co-led the financing, with participation from new backers Bain Capital Ventures and Redpoint.
A roster of existing investors also returned for the Series B, including 8VC, Ballistic Ventures, Alphabet Inc.’s GV, In-Q-Tel, Kleiner Perkins, and Menlo Ventures. Armadin announced it will use the newly raised capital to scale its agentic security platform, expand its research and AI model training programs, and accelerate its go-to-market operations for government agencies and Fortune 500 enterprises.