Valero Energy is trading 4.92% down at $405.77 after an explosion and fire at its Port Arthur refinery prompted a shutdown. - The incident occurred Monday evening at a diesel hydrotreater; Valero confirmed a fire, and all personnel were accounted for. - The refinery has capacity of 380,000 barrels per day, according to reporting published October 27, 2026. - The outage is the clearest company-specific explanation for the sharp decline.