This publication describes a policy agenda for applying the Water-Energy-Food-Ecosystems (WEFE) nexus approach to water finance and investments. It presents the conclusions and recommendations of the 4th Conference on Water Finance and Investment co-organised on 30th-31st October 2023 in Cairo (Egypt) by the Union for the Mediterranean (UfM), European Union (EU) Delegation in Egypt, and the African Development Bank, in partnership with the Egyptian Ministry of Water Resources, and with financial support from Sweden. The first conference took place in Rome (Italy) in December 2019 and, after a pause due to the impact of the Covid-19 pandemic, subsequent conferences have taken place annually since 2021 in Cairo (Egypt) in the framework of Cairo Water Week.