We examine the source of capital for sustainable development and the existence of a green bond premium in the primary and secondary bond markets in the Asia-Pacific and European markets using the more powerful Coarsened Exact Matching (CEM) method in conjunction with the Synthetic Minority Oversampling Technique (SMOTE) to address the data imbalance between green and conventional bonds. We document that green bond yields are significantly lower than conventional bond yields in both the primary and secondary markets in the Asia-Pacific, but not in Europe. This establishes the presence of a negative green bond premium in the Asia-Pacific market. In Europe, green bond premiums are either insignificant or positive. We find that green bonds have a lower risk relative to conventional bonds and show that investment grade issuers and bonds issued in the local currency are associated with lower green bond yields due to their higher credit ratings, better reputation, and absence of foreign exchange risk. In Europe, the presence of external reviews significantly induces a lower green bond yield as the credibility of issuers is enhanced.