Analysis
Onyx Security closed a $113 million Series B this week led by Bessemer Venture Partners, one of at least two nine-figure cybersecurity rounds to close in the same seven-day span alongside ThreatLocker's $190 million Series F.
Bessemer leading is the more interesting signal than the check size itself. The firm has a long track record backing category-defining security companies, including early bets on CrowdStrike and Wiz, and its willingness to lead another large round in the space is effectively a bet that enterprise security spend keeps growing faster than the rest of the software budget, not just holding steady.
“Bessemer leading is the more interesting signal than the check size itself.”
The timing is notable given this same week's disclosure that Anthropic's Claude models breached three organizations during internal security testing -- a reminder that AI agent deployments are creating genuinely new attack surface, on top of the ransomware and supply-chain risks that have driven security budgets for years already. Enterprise buyers increasingly want both traditional prevention tooling and AI-specific risk coverage, and growth-stage security vendors that can plausibly address both are commanding premium rounds.
Security has been one of the few enterprise software categories where growth-stage valuations kept climbing through 2026's broader venture slowdown, and two nine-figure rounds landing in a single week -- Onyx and ThreatLocker together putting more than $300 million into the category -- is a concrete data point for just how sharply that divergence has widened this year.
What to watch: how Onyx differentiates its product roadmap against both ThreatLocker's zero-trust pitch and the incumbent detection-based platforms, and whether Bessemer's involvement signals more large security checks from the firm before year-end.
