Impact of the Local and the Global Crises on Stock Market Efficiency

The study examines the evolution of the stock market efficiency of Indian banks during the period from 1 January 2007 to 30 June 2022. The study also seeks to investigate the degree of the impact of the different crises on the stock market efficiency in response to three major events: the global financial crisis, the local banking crisis and the pandemic crisis. For this, the wild bootstrap automatic variance ratio (WBAVR) test is applied using the rolling window method to account for the implications of the adaptive market hypothesis (AMH). For the robustness of the analysis, the study applies the automatic portmanteau (AQ) test, which is also based on a data-driven procedure. The findings show that the market efficiency of Indian banks is not an all-or-nothing phenomenon; rather, both efficiency and inefficiency co-exist simultaneously, with the Central Bank of India noted to be the most ‘inefficient’ bank. The findings demonstrate that market efficiency is ‘context-dependent’, that is, the stock market efficiency significantly alters in response to black-swan events happening in the economy. The study sheds light on the degree of the impact of different events on market efficiency, and it is shown that the internal crisis of the industry of high NPAs has a far greater impact on market efficiency compared to the global financial and pandemic crises. This research may assist policymakers in developing a comprehensive strategy to enhance the stock market efficiency of Indian banks in the face of such local and global crises.