Evaluating ESG Sustainability Performance in the Turkish Banking Industry: A Grey LOPCOW-MSD-PIV Approach

This study introduces a novel grey-based multi-criteria decision-making (MCDM) framework designed to assess the Environmental, Social, and Governance (ESG) sustainability performance of banks listed on Borsa İstanbul (BIST). The suggested hybrid grey-based model integrates two objective weighting techniques—Grey Logarithmic Percentage Change-Driven Objective Weighting (G-LOPCOW) and Grey Modified Standard Deviation (G-MSD)—with the Grey Preference Index Value (G-PIV) ranking procedure to effectively manage epistemic uncertainty inherent in sustainability data. Ten ESG indicators obtained from the Refinitiv Eikon database for the 2021–2023 period form the analytical foundation of the sustainability assessment. The integrated weighting process identifies community engagement, product responsibility, and shareholder relations as the most influential determinants shaping banks’ sustainability profiles. Based on the G-PIV results, İşbank, Yapı Kredi, and TSKB rank as the top-performing institutions. The empirical findings not only provide valuable insights into the ESG positioning of Turkish banks but also offer a replicable methodological framework for practitioners and policymakers seeking data-driven sustainability benchmarking. Furthermore, the study contributes to the growing body of literature on grey system-based decision models, reinforcing their utility in addressing ambiguity and partial information in complex financial and sustainability evaluations.