Martin Rehák is the founder and chief executive of Resistant AI, the Prague company that catches forged documents and fraudulent transactions for lenders, payment companies, and fintechs. He started it in 2019, six years after selling his first company to Cisco.
An Engineer and a Researcher
Rehák earned an engineering degree from École Centrale Paris and a PhD in artificial intelligence from the Czech Technical University in Prague, where he also researched and lectured on cybersecurity. His field was the use of machine learning to find attackers hiding in network traffic.
Cognitive Security and Cisco
He founded Cognitive Security to turn that research into a product and was its chief executive until Cisco bought it in 2013. The company became the basis for Cisco’s Cognitive Threat Analytics team, which he then led, detecting advanced threats by analyzing network traffic for more than 25 million users worldwide.
Resistant AI
In 2019 he founded Resistant AI to protect the machine learning that banks and fintechs use for credit scoring, fraud detection, and anti-money laundering from manipulation. GV led a $16.6 million Series A in 2021, and in October 2025 DTCP led a $25 million Series B, with Experian, GV, and Notion Capital returning. The company had reached breakeven the month before and employs more than 100 people in Prague, London, and New York, serving customers that include Payoneer, Close Brothers, and AXA.
It competes with SEON, Sardine, and Hawk. Rehák’s career has followed one thread from network security to forged bank statements: attackers adapt to whatever defenses they face, so the defenses have to learn faster than they do.
