Whether in response to robo advising, artificial intelligence, or cryptocurrencies such as Bitcoin, regulators around the world have made it a top policy priority to supervise the exponential growth of financial technology (or “fintech”) in the post-crisis era. However, applying traditional regulatory strategies to new technological ecosystems has proved conceptually difficult. Part of the challenge lies in managing the trade-offs that accompany the regulation of innovations that could, conceivably, both help and hurt consumers as well as market participants. Problems also arise from the common assumption that today’s fintech is a mere continuation of the story of innovation that has shaped finance for centuries. This Article offers a new theoretical framework for understanding and regulating fintech by showing how the supervision of financial innovation is invariably bound by what can be described as a policy trilemma. Specifically, we argue that when seeking to provide clear rules, maintain market integrity, and encourage financial innovation, regulators have long been able to achieve, at best, only two out of these three goals. Moreover, today’s innovations exacerbate the trade-offs historically embodied in the trilemma by breaking down financial services supply chains into discrete parts and disintermediating traditional functions using cutting edge, but untested, technologies, thereby introducing unprecedented uncertainty as to their risks and benefits. This Article seeks to catalogue the strategies taken by regulatory authorities to navigate the trilemma, and posits them as operating across a spectrum of interrelated responses. The Article then proposes supplemental administrative tools to support not only market, but also regulatory experimentation and innovation.