Fifteen years ago, the European Investment Bank (EIB) issued the world’s first green bond. From that initial seed has grown a trillion euro market, spanning different financing formats, currencies, countries and issuers across the globe. But integrity is just as important as size. Concerted effort from the bank of the EU has helped the market evolve to prioritise impact over intent, turning use-of-proceeds bonds specifically into one of the most effective tools for promoting clarity in sustainability.