Paper examines the impact of ownership structure of oil revenues (government vs. private) on financial markets development via the channel of political institutions, covering 82 oil-producing countries during the period, 1990-2015. Using the fixed effects model, the findings of the study show that oil revenue management has a threshold effect on financial development, especially financial institutions, driven by the quality of political institutions. Government's share of oil revenue investment negatively and significantly affects the efficiency of financial institutions at weak levels of political institutions, and is positive when the institutions are strengthened. Similarly, the private share of oil revenue investment on depth and access to financial institutions is negative when political institutions are weak. Furthermore, a similar analysis, based on financial markets only shows a threshold effect in the case of private oil revenue investment on both depth and access dimensions of financial markets in the developing countries sub-sample. The study, therefore, recommends that strengthening political institutions is good to stimulate the effect of oil revenues investment on financial markets development in oil-producing countries, especially financial institutions