The AI security startup Armadin has completed a Series B funding round of $255.5 million, led by Andreessen Horowitz and Accel. The new valuation of over $2.5 billion comes just seven months after the public launch in March 2026.
The company was founded by Kevin Mandia, who previously sold the security provider Mandiant to Google.
Agent Swarm Tests Corporate Networks Continuously
Armadin replaces traditional, point-in-time penetration tests with a continuous deployment of specialized AI agents that scan for attack surfaces and chain individual small vulnerabilities into complete attack paths – without privileged credentials or access to the customers' source code.
While companies typically commission traditional security tests externally only once a year, Armadin's agents reportedly run continuously in the background. A control layer, which the company says was trained by human security experts, checks each agent action in advance before it is executed.
As SecurityWeek reports, Armadin deployed around 26,000 agents in a test run in August 2026, executing 17 million offensive actions across 1,300 attacks against more than 25,000 services – independently unverified figures from company statements.
This produced 238 security findings, of which 98 were classified as significant, plus 38 confirmed attack paths. According to the company, such agent campaigns are already running in production at Fortune 500 companies and government agencies, which Armadin sells as a subscription platform rather than as individual consulting engagements.
Investors and Founder Accelerate the Race
The Series B was led by existing backers Andreessen Horowitz and Accel; new investors Bain Capital Ventures and Redpoint joined, alongside Google Ventures, Kleiner Perkins, Menlo Ventures, 8VC, Ballistic Ventures and the CIA-affiliated fund In-Q-Tel, as TechCrunch reports.
Armadin had raised a $190 million Series A only in March 2026, after the company quietly launched with $24 million in seed funding in late 2025. In total, Armadin has now raised $445 million within seven months of public operation.
The round fits a pattern of large investments in AI security firms: just in August, Anaconda acquired audit provider Enkrypt AI, and even outside the security sector, young AI companies such as the one behind the Mirendil valuation are currently negotiating billion-dollar sums.
Founder Mandia, who started Mandiant in 2004 and sold it to Google for $5.4 billion in 2022, justifies the new approach by arguing that AI lets attackers find and chain vulnerabilities faster than any human team could. The leadership team also includes Chief Technology Officer Travis Lanham, former Chief Offensive Security Officer Evan Peña, and Chief Architect David Slater, according to the company.
It remains an open question whether the same technology Armadin uses to protect companies could just as easily be turned against them if comparable agent swarms fell into the wrong hands. Armadin has not announced a public date for its next funding round or a possible IPO.
