Abstract
Good financial values are not sufficient alone for the survival of today’s businesses, which sustain their existence in the global competitive environment. For businesses to continue their activities, the expression of sustainability has come to the forefront, and therefore, the concept of corporate sustainability emerged from social, economic, and environmental obligations. The Sustainability Index is calculated under the umbrella of Borsa Istanbul to ensure that businesses implement their sustainability strategies on economic, environmental, and social issues and inform investors. The purpose of the study was to investigate whether the stock market performance indicators of the six banks which have the right to be traded in the framework of the BIST Sustainability Index for 2013, when they were not included in the index, and for 2020, when they were included, by using the Paired t-test. As a result of the analyses made for this purpose, significant differences were detected for the price/earnings ratio, market value/book value, transaction volume, and cash flow rate variables aside from share price. It was interesting that only the transaction volume increased for banks after they were included in the index. Borsa Istanbul Sustainability Index is considered a new index, and it is considered that the effect of banks on stock values and other performance indicators will turn positive as the index deepens.