South32 Ltd's stock fell sharply by 5.10% during intraday trading on Monday, following the company's announcement that it has placed its Mozal aluminium smelter in Mozambique on care and maintenance.

The diversified miner confirmed it failed to secure sufficient and affordable power supply for the Mozal smelter beyond March 2026, resulting in the shutdown of operations. The Mozal smelter, in which South32 holds a 63.7% stake, accounted for just over 29% of the company's total aluminium production in fiscal 2025, making it a significant contributor to output.

South32 had previously flagged a $372 million impairment for the Mozal smelter in its fiscal year 2025 results, reflecting the financial impact of the anticipated shutdown. The company will now sell alumina from its Worsley Alumina refinery to third-party customers at index-linked prices instead of supplying it to the Mozal facility.