Rein Security Raises $25 Million in Series A for AI Agent Controls

Rein Security raised $25 million in Series A financing announced Oct. 8, 2026, at 6 a.m. ET (10:00 UTC), giving the AI-agent security company $35 million in total funding.

Glilot Capital and Sienna Venture Capital co-led the round. Corner Ventures, Atlacle and RNP Capital Advisors also participated. Rein plans to use the money for product development, agentic-AI research and global hiring.

Founded in 2024 and co-headquartered in New York City and Tel Aviv, Rein provides runtime controls for artificial intelligence agents. Its platform uses patented sidecar technology at runtime to monitor agent code and resource access, govern activity and block harmful actions in real time. The system does not route company or customer data through a gateway or proxy.

Revenue increased eightfold and the customer base grew fivefold after the platform launched in January 2026. Rein’s platform now secures thousands of AI agents carrying out millions of actions.

Dun & Bradstreet and Lemonade are Rein customers, while Flex and Swimlane are among its new customers. The company’s research team also demonstrated the compromise of an AI shopping agent belonging to a top-five U.S. retailer at Black Hat USA 2026.

“Enterprise AI agents are becoming essential to how businesses operate, but security hasn’t kept pace with the autonomy these systems now have,” Matan Bar-Efrat, Rein’s co-founder and CEO, said. “This funding enables us to keep building the infrastructure enterprises need to deploy AI agents with visibility, control and confidence.”

AI agents can independently operate across enterprise software, information and processes. Rein’s approach is focused on observing those actions while they occur and applying controls during execution.

The funding follows Reco’s $55 million financing to expand its AI agent security platform. “The agent economy is upon us, and the rapid adoption of AI agents is creating a fundamental shift in enterprise security,” said Arik Kleinstein at Glilot Capital.