Kevin Mandia’s new ‘agent swarm’ security startup Armadin raises $255.5M at $2.5B valuation

Armadin, the new cybersecurity startup from Mandiant founder Kevin Mandia, raised $255.5 million in a Series B led by Andreessen Horowitz and Accel. The company has now raised more than $445 million and is building agentic swarm technology that continuously tests enterprise defenses by chaining vulnerabilities like an attacker would.

The funding shows strong investor demand for security tools designed around AI-native threats rather than periodic human-led penetration tests. Armadin’s approach reflects a broader shift toward continuous defense validation, as enterprises prepare for attackers and autonomous agents that can exploit weaknesses faster than traditional security cycles can respond.