Bond markets in the GCC countries are underdeveloped, and the capital mix is heavily skewed towards banks, while ambitious development plans in fields like petrochemicals and infrastructure, as well as a rapidly growing population, create an increased need for finance. This study outlines the structure of various segments of GCC financial markets and points to regulatory challenges and future developments, ranging from capital market structures to the planned GCC Monetary Union, Islamic banking, and sovereign wealth funds. The work brings together state-of-the-art analysis by international scholars who participated in a major joint initiative by the EU and the GCC, the al-Jisr Gulf-Europe Research Program.