HiddenLayer closes $100M Series B to harden AI agent and model security across the enterprise stack.
The AMW Read
Same $100M Series B already covered by AMW on 2026-09-02; this later write-up adds Agent Harness Security detail but doesn't change the segment-level read, and the round is well under the cross.§D capital threshold.
HiddenLayer closes $100M Series B to harden AI agent and model security across the enterprise stack.
HiddenLayer, a US-based AI security startup founded in 2022, raised a $100M Series B led by Delta-v Capital, with participation from Ten Eleven Ventures, Morgan Stanley, Microsoft's M12, and Booz Allen Ventures. Its HiddenLayer AI Security Platform spans AI Supply Chain Security — a Model Scanner and an AI Bill of Materials (AIBOM) that check third-party models for malware, vulnerabilities, and tampering before deployment — and AI Runtime Security, which monitors inputs and outputs of live LLM applications to block malicious prompts and unsafe responses. In August 2026 the company launched Agent Harness Security, extending that runtime protection to the execution environments of AI coding agents, targeting behavior manipulation, tool misuse, and unauthorized actions.
The raise tracks a shift in what enterprises need to secure as they let AI agents execute code and operate tools directly: exposure moves from a static model file to an agent's live, autonomous actions, and this round funds a platform purpose-built for that runtime layer rather than adapted general application-security tooling. Per the AI Market Watch index, HiddenLayer has raised $156M total since founding — a figure bounded by the roughly 5,000 companies the index tracks, not a full record of the company's fundraising.
For builders shipping autonomous coding or workflow agents, expect runtime behavior monitoring — not just pre-deployment model scanning — to become part of enterprise procurement checklists, especially with Microsoft and Morgan Stanley among the investors signaling hyperscaler- and finance-sector distribution. For investors, the open question is whether agent-security spend scales with the pace of agent deployment or stays concentrated among large regulated buyers; HiddenLayer's move to add sales partners and expand internationally with this round is a bet on the former.
