Cybersecurity startup Rein Security has gathered $25 million in a Series A investment round, pushing its overall funding to $35 million. Venture capital firms Glilot Capital Partners and Sienna Venture Capital jointly led the transaction. Corner Ventures, Atlacle, and RNP Capital Advisors also contributed to the financing round.
The company designs runtime defense software specifically for organizations deploying autonomous artificial intelligence agents. Built around a patented sidecar architecture, the tool functions directly alongside active software agents rather than steering traffic across an intermediary gateway or proxy. The system grants enterprise security teams code-level visibility into agent operations, establishes behavioral controls, and imposes real-time constraints to block destructive commands before they occur.
Corporate interest in specialized oversight software has surged because autonomous programs frequently hold direct permissions across critical business databases and operating tools. Since introducing its commercial system in January 2026, Rein has expanded its client list fivefold and increased revenue by eight times. Customers currently utilizing the platform to protect thousands of active agents include financial and insurance companies such as Lemonade and Dun & Bradstreet.
Rein plans to spend the incoming capital to speed up platform engineering, enlarge its workforce internationally, and support dedicated research into software vulnerabilities handled by its internal testing division, Agent Breakers. Chief executive Matan Bar-Efrat and Netanel Rubin established the business in 2024. The enterprise maintains offices in Tel Aviv and New York and currently employs 31 workers.