Abnormal Security

CybersecurityFounded 2018

Market Data Current As Of: September 12, 2026

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Abnormal Security

CybersecurityFounded 2018

Reviewed by Swet Parvadiya

Last reviewed: September 12, 2026

Market Data Current As Of: September 12, 2026

Founders

Who Founded Abnormal Security?

Evan Reiser, Sanjay Jeyakumar · Founded 2018 · San Francisco, California, United States

Quick Answer

Abnormal Security was founded by Evan Reiser, Sanjay Jeyakumar in 2018 in San Francisco, California, United States.

Founding Story

In 2017, Evan Reiser and Sanjay Jeyakumar were reflecting on their decade of experience building hyperscale machine learning systems at Twitter, TellApart, and Google. At Twitter, they had architected models that evaluated billions of real-time signals to predict human clicks and detect bot fraud. Meeting with Chief Information Security Officers (CISOs), they were shocked to discover that despite spending billions on cybersecurity, enterprises were consistently falling victim to Business Email Compromise: CFOs were wire-transferring millions of dollars to cybercriminals impersonating company executives. The founders realized that traditional email security tools were fundamentally flawed because they lacked context: a gateway evaluating an incoming email has no idea who usually talks to whom, how an executive typically phrases an urgent request, or what a regular vendor invoice looks like. In 2018, Reiser and Jeyakumar incorporated Abnormal Security in San Francisco. Backed by Greylock Partners, they built an API-first engine that connects directly to Microsoft 365 and Google Workspace, ingesting months of historical communication data in minutes to build dynamic baseline behavioral profiles for every employee, vendor, and customer in an organization.

Evan Reiser

Role at Abnormal Security

Evan Reiser is an American technology entrepreneur, computer systems engineer, and cybersecurity executive who co-founded Abnormal Security in 2018 and serves as its CEO. Reiser graduated from Washington University in St. Louis with a degree in computer science. Prior to founding Abnormal, Reiser co-founded BloomSpot (acquired by Chase) and served as Head of Product at TellApart, an ad-tech machine learning platform acquired by Twitter for $532 million. At Twitter, Reiser led the machine learning and product teams responsible for commercial monetization, processing billions of real-time behavioral signals daily. At Abnormal, Reiser has spearheaded company strategy, enterprise customer acquisition, and technological innovation, scaling Abnormal into a $5.1 billion market leader protecting over 15% of the Fortune 500.

Sanjay Jeyakumar

Role at Abnormal Security

Sanjay Jeyakumar is a Canadian-American software engineer, distributed systems architect, and artificial intelligence executive who co-founded Abnormal Security in 2018, serving as Chief Technology Officer. Jeyakumar earned a degree in computer engineering from the University of Waterloo. He spent early years in systems engineering at Google before joining TellApart as a foundational architect. Following TellApart's acquisition by Twitter, Jeyakumar served as an engineering architect at Twitter, designing hyperscale real-time data streaming pipelines and machine learning infrastructure. As CTO of Abnormal, Jeyakumar designed the core behavioral AI engine, leading the development of the multi-dimensional feature extraction pipelines that analyze 45,000 signals per message in real time.

Who Founded Abnormal Security? FAQ

Who founded Abnormal Security and in what year was it established?

Abnormal Security was founded in 2018 by Evan Reiser, Sanjay Jeyakumar in San Francisco, California, United States.

What was the original founding vision for Abnormal Security?

The founders established Abnormal Security with the objective of solving core inefficiencies in Cybersecurity, AI Email Security, Cloud Security, Behavioral AI, Business Email Compromise (BEC) & Threat Detection, laying the foundation for its current global scale.