Stock market reactions to sustainable mergers and acquisitions. Perform an extensive academic literature review on how the ESG (sustainability) factor affects the acquirer's stock price at the moment of the merger announcement. In the introduction consider the ESG and sustainable investments in general. In the literature review, part consider the latest studies in this field, find whether firms with higher ESG factor (sustainable performance) have higher abnormal returns during the event window. Also include the event study methodology in relation to this research problem.