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Abnormal AI is an AI-native human behavior security platform that protects employees from socially engineered email and account-compromise attacks. Its behavioral AI models analyze identity, communication, and content signals to detect targeted phishing, business email compromise, and account takeovers across cloud email and collaboration tools.
Abnormal AI is an AI-native human behavior security platform that protects employees from socially engineered email and account-compromise attacks. Its behavioral AI models analyze identity, communication, and content signals to detect targeted phishing, business email compromise, and account takeovers across cloud email and collaboration tools.
Abnormal was founded in 2018 by Evan Reiser (CEO) and Sanjay Jeyakumar (CTO). The pair met at TellApart, a Greylock-incubated ad-tech company acquired by Twitter in 2015, where they applied machine learning to advertising. After noticing how enterprises were losing money to socially engineered email attacks that cloud email providers were not preventing, they left Twitter to apply similar ML techniques to email security. The company operated as Abnormal Security from launch and rebranded back to its original name, Abnormal AI, in April 2025.
Abnormal Security returned to its original name, Abnormal AI, reflecting its AI-native positioning and expansion beyond email security.
CEO Evan Reiser posted on LinkedIn announcing the rebrand to Abnormal AI and the company's broader platform vision.
Abnormal published a blog post explaining the return to the Abnormal AI name and the company's AI-native heritage.
Abnormal Security closed a $250M Series D led by Wellington Management with Greylock, Menlo Ventures, Insight Partners, and CrowdStrike Falcon Fund participating; ARR surpassed $200M.
CNBC covered the Series D, noting the $5.1B valuation and Abnormal's growth in AI-driven email security.
Abnormal Security raised a $210M Series C led by Insight Partners with Greylock and Menlo Ventures participating, at a $4B valuation.
Menlo Ventures led a $50M Series B in Abnormal Security with Greylock participating.
$534M raised total