Sam Blackshear is walking away from Mysten Labs. The cofounder and CTO announced August 6 he's joining Anthropic to focus on defensive security research as artificial intelligence models grow sharper at finding software vulnerabilities. He'll stay on as an adviser to the Sui blockchain ecosystem, but the day-to-day technical leadership role belongs to Evan Cheng now.
Blackshear spent the last years building infrastructure for Sui, a layer-1 blockchain backed by major venture firms. He was hands-on with the technical architecture, but he said the move lets him return to pure engineering work on a new problem. The shift comes as he watches the security landscape change. "The balance of power between attackers and defenders is shifting," he posted on X. That's his read on where things are heading, not a formal industry assessment, but Anthropic's own research backs the worry. Their Claude Opus 4.6 model can spot high-severity vulnerabilities at scale. The company runs a Frontier Red Team studying how advanced AI could be weaponized for offense or hardened for defense.
Evan Cheng takes over the technical vision. Cheng co-founded Mysten with Blackshear and has been CEO since day one. He recruited most of the engineering talent and spent time at Apple and Meta before diving into crypto. The company didn't release a formal succession plan, but Blackshear made clear Cheng has the skills for the job. Mysten also mentioned a foundation is in development, and Blackshear intends to stay involved even after that launches.
The timing is worth noting. Anthropic is ramping up defensive cyber research exactly when frontier models are starting to matter for security work. Blackshear didn't disclose his start date or reporting structure, but the hire signals Anthropic sees AI security as a core competency as capabilities improve.
This is informational content about industry moves and research. It is not financial or investment advice.
