There are many impacts that Merger and Acquisition (M&A) event announcements can have on the capital market. The competitive aspects are among the necessary in the analysis of this type of event. Impacts on the sector structure can be beneficial or harmful not only to the competitors but also to the suppliers and consumers. Internationally, a M&A announcement results in value creation for shareholders of competing companies. The real causes of this effect are not conclusive yet and this situation is highlighted in Brazil, where research on this subject is scarce. Thus, the objective of this research is to identify the creation or destruction of value to the listed competitors companies during the period of announcement of Merger and Acquisition events. A total of 123 M&A announcements in 5 sectors were analyzed in Brazil: banking, pulp and paper, construction, education and telecommunications. Through the event study methodology, one sought to analyze the impact of the M&A announcement on the market value of competing companies. The results showed that a M&A event is beneficial not only to competitors but also to all other capital market companies in the competitive sectors from 2003 to 2017. However, the behavior of accumulated abnormal returns (CAR) varies according to the behavior pattern of the sectoral GDP and the Bovespa index and it is also relative to the size of the deal value. The analyzed sample shows that when the market analyze the target as a threat, the M&A is seen as positive for competitors. On the other hand, when the M&A is negatively viewed by other companies, the cost factor becomes more relevant as the increasement of market power for the company resulting from the M&A increases its bargaining power towards suppliers and consumers.