Market Share as a Function of Board Diversity and Board Size of Selected Deposit Money Banks in Nigeria 1. Introduction Banks Success has been the focus of academic and policy debate in developed and developing economies of the world. Deposit money banks around the world have been experiencing challenges over the years in the area of survival and market share. These challenges are attributable to weak or defective corporate governance mechanisms. The nature and mode of management and application of corporate governance mechanisms go a long way to influence the success of an organization. Organizational success depends to a great extent on the mode of operations and corporate governance schemes that are existent in an organization without which leads to corporate failure or demise (Aliyu, 2016; Hamden, 2014). Developing countries of the world need to adopt an effective and more efficient corporate governance structure to solve the aforementioned problems and encourage/embrace new practices for implementing the different characteristics of corporate governance in developing economies (Mulili & Wong, 2011). In developing countries, improving corporate governance could provide and promote various important public policy objectives. For example, good CG reduces the extent of vulnerability of the developing countries to financial crises, reinforces property rights, reduces transaction costs and the cost of capital, improves firm performance, and enhances the capital market and consequently ensure success of an enterprise (Al-Matari & Al-Arussi, 2016). Therefore, the ability of the developing countries such as Nigeria to benefit from these listed advantages depends on how quickly and effectively, they can resolve their socioeconomic and political