The present paper is an attempt to investigate the effect of a merger in the performance of Kotak Mahindra Bank. It has been found that merger has a significant importance in the performance of an organisation. For this paper, we study the pre- and post-merger performance of Kotak Mahindra Bank with ING Vyasa with effect from April 1, 2015. The study emphasizes on verification of proposed merger benefits including improved asset diversification, enhanced product delivery systems, and a reduction in operating and funding costs and analyses the operating efficiency post the merger. From the study, it is observed that Kotak Mahindra Bank had a stable financial performance during the last 16 quarters that is 4 years. Among all these quarters, the last 4 quarters showed slightly lower performance in terms of net income margin, earnings per employees, business per employees, debt equity ratio, proprietary ratio, and current ratio. These can be due to the increment cost which might have been occurring due to the merger with ING Vysya.