Abnormal Security raised $250 million in Series D funding at a $5.1 billion valuation to expand its behavioral AI platform for email threat detection. The company’s approach focuses on understanding human communication patterns rather than relying solely on static rule-based filtering.

As phishing and business email compromise attacks grow more sophisticated, behavioral AI has emerged as a critical layer of enterprise cybersecurity. The new capital supports product expansion, global enterprise adoption, and continued investment in machine learning systems designed to identify subtle anomalies in real time.