Effects from the news about Samarco disaster
in Mariana: an event study about Vale and BHP

Name: SABRINA SOBRINHO BARCELLOS

Publication date: 25/06/2018
Advisor:

Namesort descending Role
GABRIEL MOREIRA CAMPOS Advisor *

Examining board:

Namesort descending Role
DIANE ROSSI MAXIMIANO REINA Internal Examiner *
GABRIEL MOREIRA CAMPOS Advisor *

Summary: From the twentieth century, organizations started to worry about sustainable
development, that is, to generate economic development without forgetting
socio-environmental issues. This new paradigm does not exclude the need for
wealth generation and return to shareholders. Given the complexity of the
environmental relationship and performance in the stock markets, this research
intends to study, in the context of the Mariana disaster involving Samarco,
whether news released by Vale and BHP companies on November 2015
affected the return of companies. We used the event study methodology,
derived from the Efficient- Market Hypothesis, to determine if the news
disclosed by these companies in the period from November 5, 2015 to June 30,
2017 affected the return of the shares of the controlling companies of Samarco:
Vale and BHP. Thus event windows were made to check the abnormal returns
seven days before and after each news. Thus, of all the news released by the
companies during the period of analysis, there were 26 news stories released
by Vale and 13 by BHP. The results indicate that the market reacted statistically
to 57.7% of the news published by Vale and 61% of the news reported by BHP.
It was observed that among the significant news, those that indicated losses in
processes or financial results below expectations, brought negative returns,
while disclosures about agreements and release of resources to minimize the
damages of the disaster, were directly related to abnormal positive returns.
News related to Samarco's and its parent's attempts to mitigate damages were
generally unrelated to abnormal returns. Further research may further study the
disclosures about environmental information that most impact the abnormal
return in the event of disasters.

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