QUARTERLY PERFORMANCE AND STABILITY PATTERNS OF THE TURKISH LARGEST COMMERCIAL BANKS: AN APPLICATION OF DATA ENVELOPMENT WINDOW ANALYSIS

Between the years 2003 and 2009, in a 'new' macroeconomic environment with low inflation, Turkish banks increased loans and made efforts to operate efficiently to maintain their profitability and growth. In this context, this study evaluates the performance of the sector and dynamic efficiency and stability trends of Turkish banking, between the periods of December 2003 - March 2009 in a quarterly basis. A two-stage analysis is performed on the financial ratios of largest banks which control vast majority of the market. Firstly, in order to deal with proper variables as inputs and outputs in the efficiency study, and to measure financial performance over time objectively, weights of pre-selected financial ratios are determined via Shannon's entropy measure. With these objective weights, a performance index of the sector during the analysis period is calculated and presented. After choosing the most important ratios as input and output variables, we evaluate the relative efficiency and stability patterns of large Turkish banks. via Data Envelopment Window Analysis over a period of 21 quarters with a window width of 4 (a year).