Market power and efficiency as the source of performance in banking: a case study of the Slovak banking sector

In an attempt to explain the sources of performance in the Slovak banking sector, the paper inquiries whether performance of Slovak banking institutions can be traced to market structure (as suggested by two market-power hypotheses) or should rather be attributed to efficiency (as postulated by two efficient-structure hypotheses). The empirical investigation is conducted with respect to two measures of banking performance and for a period of 11 years from 2005 to 2015 with some novel features in comparison to the state of the art in the field. First, the model of banking production accounts for both the intermediation and production aspects of banking operations and adapts the network slacks-based measure model in order to obtain trustworthy estimates of X-efficiencies and scale efficiencies. Second, the used simultaneous equations model involving all the four hypotheses of interest accommodates both performance measures at a time and avoids thus separate estimation. Third, the method of hypothesis verification hinges on testing composite hypotheses and refrains from step-wise estimation of nested models and significance testing of isolated parameters. A variant of the efficient-structure hypothesis in which both X-efficiency and scale efficiency exert its influence upon performance is established as descriptive for major Slovak commercial banking institutions.