Under the hegemony of New Public Management, local governments have been targeted by professional service firms (PSFs) resulting in outsourcing, reorganization, and marketization of public services. More recently, the local state has also increasingly been exposed to the influence of financial market actors, dynamics, and rationalities. The chapter illustrates this process of state financialization by tracing the emergence and consolidation of municipal debt management policies including the use of interest rate derivatives in the UK and Germany. This process is interpreted as a techno-political project crucially driven by private expertise and actively spearheaded by particular PSFs, namely treasury management advisors and brokers. Five stages of their involvement are identified and empirically illustrated: The crafting of a new debt management narrative, the provision of trial portfolio analyses, the canvassing, brokering, and contracting of derivative deals, the actual debt management operations, and crisis management.