421 1. INTRODUCTION Mining plays a critical role in supplying the minerals required for global economic development and the energy transition. However, the sector is also exposed to environmental risks that can materialize through tailings dam failures, contamination events, and regulatory sanctions. These events not only generate environmental and social impacts, but may also affect the financial valuation of mining firms. Previous research has shown that environmental incidents can lead to negative stock market reactions for directly responsible firms, particularly when events are severe or widely publicized (Assis et al., 2023; Bourdeau-Brien & Kryzanowski, 2017; Capelle-Blancard & Laguna, 2010). However, less attention has been given to whether these shocks extend beyond the responsible firm and affect other companies operating in the same sector. This question is particularly relevant in the mining industry, where firms often share similar operational risks, regulatory environments, and reputational exposure. If investors perceive environmental risk as partially shared across firms, a negative event affecting one company could trigger a reassessment of the entire sector. This mechanism is consistent with the idea of reputational spillovers and sectoral contagion in financial markets. The objective of this paper is to evaluate whether major mining-related environmental events generate (i) statistically and economically significant impacts on responsible firms, and (ii) spillover effects on related peer companies. The analysis is based on a sample of ten welldocumented events involving major global mining firms and applies a standard event-study methodology. The contribution of this study is twofold. First, it provides a comparative analysis across multiple mining events rather than focusing on a single case. Second, it explicitly evaluates spillover effects using aggregated measures across peer firms, allowing for a more robust interpretation of sectoral contagion. 2. METHODOLOGY 2.1 Event study framework The empirical analysis is based on the event study methodology originally developed by Fama et al. (1969) (Fama et al., 1969), which is widely used to evaluate how financial markets react to new information. Abnormal returns (AR) are estimated using the Fama–French three-factor model (Fama & French, 1993): , − , = + 1 ( , − , )+ 2 + 3 + , where , is the return of firm , , is the risk-free rate, , is the market return, and
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