摘要：This study aims to investigate the influence of market structure (market concentration and market share) to the interest sperads of publicly banks in Indonesia. We used panel data of commercial banks listed in Indonesia Stock Exchange in the year of 200 2-2012. Market concentration and market share are proxies of market structure which are controlled by banks total assets, capital risk, cost structure, and type of bank ownership. The results of the study indicate that the explanatory variables namely market concentration, market share, banks size, capital risk and banks cost structure effect on the interest spreads of publicly banks in Indonesia. Size of bank (dummy variable) effect on the interest spreads of publicly banks in Indonesia. Medium and large-sized banks proved to set deposit rates higher than smaller banks. The implication is that government should conduct more rigorous supervision of banks with large market shares because they seem to use market power to obtain wider interest spreads. This means that banks with large market shares inclined to set lower deposits rate and higher loans rate than banks with small market shares
