This study aims to analyze differences in market reactions and performance before and before announcing Mergers and Acquisitions in companies listed on the Indonesia Stock Exchange (IDX) in 2015-2019 by measuring differences in Abnormal Return (AR). Trading Volume Activity (TVA). Security Return Variability (SRV). and Actual Return (R) 10 days before and 10 days after the event. https://www.diegojavierfares.com/