Rein Security Raises $25M Series A to Guard Enterprise AI Agents
Cybersecurity startup Rein Security has secured a $25 million Series A funding round to scale its runtime security platform for enterprise AI agents.
Rein Security Raises $25M Series A to Guard Enterprise AI Agents
Cybersecurity startup Rein Security has secured a $25 million Series A funding round to scale its runtime security platform for enterprise AI agents.
Securing Autonomous Workloads
As companies increasingly grant autonomous AI agents access to their core systems, ensuring robust oversight has become a critical operational priority. Addressing this emerging challenge, cybersecurity startup Rein Security announced a $25 million Series A funding round on October 8, 2026. The latest investment brings the company's total funding to $35 million.
The New York and Tel Aviv-based startup was founded in 2024 by CEO Matan Bar-Efrat and CTO Netanel Rubin. Operating with a team of 31 employees, the company focuses on protecting enterprise AI agents during their actual execution phase, offering real-time visibility and control over the resources they touch.
Rapid Growth and Backing
The Series A financing round was co-led by Glilot Capital and Sienna Venture Capital. Additional participation came from Corner Ventures, Atlacle, and RNP Capital Advisors.
Rein Security officially launched its product in January 2026 following an $8 million seed round. According to the company, revenue has grown eightfold since the product launch, while its customer base has expanded fivefold. The platform currently secures thousands of AI agents executing millions of actions across sectors such as financial services, healthcare, and retail, with prominent clients including Dun & Bradstreet and Lemonade.
Runtime Technology and Market Projections
The startup's platform is built on patented sidecar technology that operates alongside AI agents during execution. This architecture provides security teams with runtime visibility into every line of code executed and every system resource accessed, allowing the platform to block harmful actions in real time without routing sensitive data to external parties.
The broader market for artificial intelligence security is expanding rapidly. Industry projections from Gartner indicate that the AI security market is expected to reach nearly $4.8 billion in 2027, representing a 68.7% increase from 2026, before climbing further to almost $7.7 billion by 2028.
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