1291 failure (2015), Rio Tinto – Juukan Gorge destruction (2020), Glencore plc – Konkola acid spill (2006), Anglo American – Minas-Rio tailings spill (2018), Newmont Corporation – Yanacocha mercury spill (2000), Imperial Metals – Mount Polley tailings breach (2014), Freeport-McMoRan – Grasberg contamination ruling (2018), Southern Copper – Río Sonora spill (2014), Teck Resources – Elk Valley selenium contamination (2021). For each event, one responsible firm and a set of peer firms were defined based on sectoral similarity. 2.4 Spillover analysis Spillover effects are evaluated using aggregated indicators across peer firms: Mean CAR, Median CAR, Fraction of peers with negative CAR and Fraction of peers with statistically significant CAR This approach allows identifying sectoral patterns even when individual firms do not exhibit statistical significance. 3. RESULTS 3.1 Direct effects on responsible firms Table 1 reports, for each event, the window in which the responsible firm reached its most adverse cumulative abnormal return (CAR), together with the corresponding p-value and the average response of peer firms. Figure 1 shows how CAR evolves across event windows for the responsible firms. Table 1 – Worst-window CAR results for responsible firms and average peer response Event Responsible firm Ticker Worst window CAR (respo nsible) pvalue Sign ifica nce Mean CAR (peers) % Negative peers % Signifi cant peers Interpretation Brumadinho dam collapse VALE S.A. VALE [-7,+7] -0.207 0.025 5% 0.025 33.3 0.0 Direct impact Samarco (Mariana) tailings failure BHP Group BHP [-21,+21] -0.300 0.008 1% -0.334 100.0 0.0 Direct impact + spillover Juukan Gorge destruction Rio Tinto RIO [-3,+3] -0.033 0.475 ns -0.059 100.0 0.0 Moderate spillover Konkola acid spill (Zambia) Vedanta Resources VED.L [-7,+7] -0.066 0.635 ns -0.046 66.7 0.0 Moderate spillover Tailings spill in Brazil (Minas-Rio) Anglo American NGLO Y [-14,+14] -0.055 0.545 ns -0.078 100.0 0.0 Moderate spillover Yanacocha mercury spill (Peru) Newmont Corporation NEM [-21,+21] -0.287 0.284 ns -0.098 50.0 0.0 Limited evidence Mount Polley tailings breach Imperial Metals III.TO [-14,+14] -0.464 0.000 1% -0.063 100.0 0.0 Direct impact + spillover Grasberg contamination ruling FreeportMcMoRan FCX [-14,+14] -0.135 0.230 ns -0.076 66.7 33.3 Moderate spillover Río Sonora spill (Grupo México) Southern Copper SCCO [-21,+21] -0.076 0.488 ns -0.093 100.0 0.0 Moderate spillover Elk Valley selenium contamination Teck Resources TECK [-21,+21] -0.231 0.173 ns -0.068 66.7 0.0 Moderate spillover
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