Vztah mezi koncentrací trhu a ziskovostí komerčních bank v zemích Evropské unie v období 2015-2025

This bachelor's thesis examines the relationship between banking market concentration and the profitability of commercial banks in the member states of the European Union over the period 2015–2025. The aim of the thesis is to test the validity of the Structure-Conduct-Performance paradigm, according to which higher market concentration leads to higher bank profit margins, against the competing efficiency hypothesis. The theoretical part outlines the economic role of banks, market structure and concentration theory, and the determinants of bank profitability. The practical part employs a fixed-effects/random-effects panel regression on data from 27 EU countries, measuring concentration through the Herfindahl–Hirschman Index (HHI) and profitability through the net interest margin (NIM) and return on equity (ROE). The estimation results, robust to heteroskedasticity, autocorrelation, and cross-sectional dependence (Driscoll–Kraay standard errors), show that the HHI coefficient is not statistically significant in any of the estimated specifications. Instead, the level of market interest rates emerges as the strongest and most robust determinant of profitability. The findings therefore lend more support to the efficiency hypothesis than to the market power hypothesis and suggest that the profitability of the European banking sector over the period studied was driven primarily by the monetary policy cycle rather than by market structure.