Public development banks as a system

National development banks (NDBs) can play a greater role in financing sustainable development through more effective co-operation with other public development banks. However, more evidence on existing co-operation is needed to identify opportunities and strengthen partnerships. Drawing on an original database from eight NDBs across Latin America and the Caribbean, Africa and Asia between 2018 and 2026, this paper examines the scale and nature of these partnerships. It introduces a new typology to classify financial, technical, and other institutional forms of collaboration. The analysis shows that collaboration among public development banks mobilised USD 21 billion in financial commitments over the period. Targeted investment loans account for the largest share of financial co-operation, while multilateral development banks provide more than 70% of total commitments and bilateral development banks play a complementary role. Climate finance has emerged as the fastest-growing area of collaboration. The findings also show that technical assistance and institutional co-operation often underpin financial partnerships, helping development banks strengthen their capacities and expand their impact. The paper provides new evidence on how partnerships evolve, mobilise finance and support sustainable development outcomes.