Shares of Fortescue (ASX:FMG) fell 0.6% in recent trading on Tuesday, while those of Rio Tinto Group (ASX:RIO) fell 0.2% after the Australian Financial Review reported that the iron ore miners plan to stop using S&P Global Energy Platts Iron Ore Index as a benchmark for term contracts, citing people familiar with the matter.

The shift came after criticism of the benchmark from state-backed buyer China Mineral Resources Group. It had asked Rio to use China's new domestic iron ore index, the report said.

Rio will begin using an alternative iron ore index published by Fastmarkets for cargoes loaded for China in January and February 2026, as a trial for the last two months of its long-term contract period with steel mills affiliated with the China Mineral Resources, per the report.

Meanwhile, Fortescue will use an average of China's Mysteel and the Argus Iron Ore Index for the remaining period of time in its long-term contracts with Chinese steel mills, the report said.

(Market Chatter news is derived from conversations with market professionals globally. This information is believed to be from reliable sources but may include rumor and speculation. Accuracy is not guaranteed.)