This paper extracts key variables from documented findings on bank intermediation margins of two types of banks in the Organisation of Islamic Countries. The intermediation margins used as the dependent variable are: net interest margins of conventional banks and the net profit margins of Islamic banks. To overcome the endogeneity issue of variables, an appropriate econometric procedure namely the dynamic Generalized Method of Moments is applied using data from 105 commercial banks over 14 years. The results are interesting: there is a significant difference in the margins across the two types of banks, 2.17% and 1.61% respectively. Capital adequacy, management quality, and diversification determinants significantly explain the margins of both types of banks. We also find evidence suggesting market quality matters. This is an expected result since both banks operate, despite their inherent institutional differences, in a competitive environment to meet the core demands for funds, which are the same, for traditional lending and borrowing activities. However, this also shows that both CBs and IBs in dual banking system are not significantly different from each other, despite the perception arising from minor institutional differences. These findings provide insights on the unique banking performance in dual banking systems.

This article focuses on the short- and long-term assets and liabilities gap and the determinants of net interest/profit margins of both conventional banks and Islamic banks in the Organization of Islamic Cooperation countries over the period from 1997 to 2010. The results show that both conventional and Islamic banks have negative short-term gaps and positive long-term gaps. These indicate that banks use short-term deposits and funding to finance long-term loans, advances and investments, taking into consideration refinancing and reinvestment risks. The findings also show that operating cost is a significant determinant of bank margins and important factor to improve quality of management in banks. Overall, the conventional banks have better quality of assets and liabilities with an optimum composition of profitable assets and low-costs liabilities. The low bank margins in conventional and Islamic banks indicate low volatility in financial markets and the growth of banking business.