The group finished the month at a total valuation of $2.26 trillion, erasing nearly 75% of the gains recorded in August. As government bond yields climbed to their highest levels since 2008, the rising cost of capital hit precious metal producers particularly hard. Gold futures dropped 6.4% to $4,158 an ounce, dragging down the 15 gold miners in the index by a combined $79 billion. Kinross Gold and Shandong Gold both suffered double-digit losses after revising their production outlooks downward, while Gold Fields saw shares slide 21% following a rejected takeover bid for Northern Star Resources.

Copper producers faced a different set of pressures despite prices remaining relatively flat. BHP suffered the largest individual dollar loss, shedding $26.4 billion as labor unrest and a fatal accident at its Escondida mine rattled investors. Meanwhile, First Quantum Minerals saw its valuation plummet by 19.2% on the final day of the month after a Panamanian commission proposed strict conditions for the Cobre Panama mine, including the forfeiture of arbitration claims. In the battery metals sector, a change in inventory reporting methodology triggered a 22.5% drop in lithium carbonate futures, forcing major players Albemarle and Ganfeng Lithium out of the Top 50 ranking entirely.