This chapter proposes a particular understanding of financialization, connected with a special approach to studying it. Some researchers see financialization as a major shift in revenue and profit distribution between actors in the economic system or at the level of a sector. With financialization, credit circuits and public circuits alike have become increasingly hybridized with the financial circuits: the banks have developed asset management activities and are offloading their loans via securitization; states and local authorities are issuing bonds and using a growing number of investment vehicles to conduct their policies. The instrument-based approach to financialization means paying attention to the practices and tools that support and facilitate financial actors’ involvement in a range of different situations, and their capture of resources. Studying financialization from a socio-technical angle means looking into the actual operations performed by the “workers” of financialization.