The rise of ‘bigtech’ finance – the provision of payment services and financial intermediation by large digital platforms – poses significant cross-border regulatory challenges with implications for financial stability. Yet despite steps to strengthen regulation at the domestic level, international cooperation in this area remains very limited. Although geopolitical rivalry over digital technology has hindered progress towards agreement on global rules, we know far less about the technical barriers to standard-setting in this new and complex field. To address this, the paper combines scholarship on international regime complexity and transnational knowledge to understand the epistemic challenges of international standard-setting in an ‘emergent’ regime complex. We argue that regulatory cooperation around bigtech is constrained by two main epistemic barriers: cognitive limits to understanding; and the existence of siloed knowledge. Furthermore, we show how international bodies strive to overcome these barriers by generating new transnational knowledge through processes of inscription and orchestration. The paper makes a wider contribution to the ‘epistemic turn’ in IPE by unpacking the contested meanings and practices of standard-setting in new regulatory fields