A large body of empirical research supports the view that a well-developed financial system contributes to economic growth.1 Further evidence suggests that the causality runs from finance. e.g., Rajan and Zingales 2003; King and Levine 1993; Levine and Renelt 1992. to growth.2 The debate that remains unresolved to this date is whether economic growth is better served through market-oriented financial systems, which is the case of the US and the UK, or bank-oriented financial systems, which is the case in the GCC countries, Japan and most of the European countries. Several studies claim that the financial system’s structure is irrelevant and what matters is the financial system's overall level of development.3 Recent studies show that financial development depends on legal and political institutions. The recent financial crisis has shown that regulators, supervisors, analysts, and academics are still lagging in their understanding of, and response to, the practice of finance. Practitioners are still motivated by profit rather than soundness. Against this background and based on the Structure-Conduct-Performance (SCP) paradigm, we aim to explore, without being limited to, the effect of structure and conduct to the overall performance of GCC financial institutions. The SCP, which is a dominant paradigm in the theory of Industrial Organization, refers to Structure as the concentration of market shares in the market, Conduct as the behavior of firms - competitive or collusive, and Performance as the extent of market power and measured by efficiency and profitability.