Armadin, started by Mandiant founder Kevin Mandia to build AI cybersecurity agents, raised a $255.5M Series B led by a16z and Accel at a $2.5B valuation (Anzar Mehraj/Reuters)

Armadin, founded by Kevin Mandia, secured $255.5 million in a Series B round led by a16z and Accel, valuing the company at $2.5 billion. The funding supports the development of AI-powered cybersecurity agents. Meanwhile, Google is deploying its Gemini 4 Argon model to a select group of cyber-defender partners as part of a voluntary pre-release program.