Access to large, long-term, and stable funding sources is a prerequisite for achieving the objectives of national development banks (NDBs). By systematically collecting data on the funding sources of NDBs worldwide, we are the first to answer the questions of what are the main types of funding sources available to NDBs, and what are the stylized facts of such funding sources. We find that public agencies and market actors are the two main sources of funding for NDBs where governments deploy both administrative measures and market-based means to mobilize funding for NDBs. In particular, NDBs can rely on government support to use market-based means to give full play to the leverage of the sovereign creditworthiness, transforming market funds into large long-term funds to advance development goals. In addition, direct and explicit funding support such as direct budgetary transfers from the government or official development assistance is also important for NDBs. Building upon the key characteristics of funding sources for NDBs worldwide, we finally propose ten research questions for future exploration from the perspective of New Structural Economics and encourage scholars who are interested in this area to conduct further research.