Adaptive Security, the leading provider of AI-powered social engineering prevention solutions, announced a $43 million funding round led by Andreessen Horowitz (a16z) and the OpenAI Startup Fund, marking OpenAI's first investment in a cybersecurity startup. Additional participating investors include Abstract Ventures, Eniac Ventures, CrossBeam Ventures and K5, along with executives from Google, Workday, Shopify, Plaid, Paxos and others. The funding will accelerate Adaptive's development of solutions to defend against AI-powered social engineering attacks.