Fastmarkets proposes changes to Asia copper concentrates index weighting, seeks feedback on normalization of gold and silver

The proposal would align the index more closely with physically traded volumes in the region, and enable it to adjust to evolving market conditions.

This proposal follows an observed widening of the spread between trader and smelter purchase components of the index and is aligned with a majority of market feedback.

Additionally, Fastmarkets seeks feedback on how to normalize gold and silver byproduct credits within this index. This would allow the index to better reflect the influence of precious metal byproducts on copper concentrates TC/RCs.

Dynamic weighting between trader, smelter purchases
Under the proposed change, Fastmarkets would use a dynamic volume weighting of trader and smelter purchases in the final index. This weighting would be adjusted weekly, based on the volume of reported inputs over a rolling six-month period.

Currently, Fastmarkets applies a fixed 50:50 weighting between the “Copper concentrates TC implied smelters purchase” and “Copper concentrates TC implied traders purchase” in the final calculation.

The following indices would be affected:
MB-CU-0287 Copper concentrates TC index, cif Asia Pacific, $ per tonne
MB-CU-0288 Copper concentrates RC index, cif Asia Pacific, US cents per lb

Normalization, assumptions for precious metals
Fastmarkets also invites feedback on the introduction of an additional normalization mechanism for gold and silver below a specified threshold; the cut-off being the point at which gold and silver contained in copper concentrates change from being unpaid to payable by the buyer.

From 2025, payables were generally charged when content volume was more than 1g for gold and 30g for silver.

This change came from sustained, unprecedented tightness since late 2023 in the copper concentrates market, fierce competition and the surge in gold and silver prices.

A normalization would capture TC/RC differentials between copper concentrates that include gold and silver credits, and those that do not.

Currently, there is no formal industry standard to account for gold and silver payables below the threshold, and Fastmarkets understands that such payable credits and deductibles can vary due to differences in precious metal content, typical assay assumptions, trading partners, counterparty practices and broader market dynamics.

Fastmarkets is seeking feedback on a normalization process for gold and silver payables below 1g for gold and 30g for silver, which could be applied on a case-by-case basis. Fastmarkets could normalize, for example, by forming a view of gold and silver prices or by asking market participants to self-normalize their bids, trades and offers to the Fastmarkets specification.

Fastmarkets’ existing gold and silver specifications, as outlined in the methodology, remain unchanged, but Fastmarkets is seeking feedback on how to normalize for gold and silver content, where the base content of gold and silver changed as outlined below.

Fastmarkets is also seeking feedback on changing the gold (Au) base specification from 1.1g per dmt to 1g per dmt, and the silver (Ag) base specification from 75g per dmt to 30g per dmt. The maximum for gold and silver would remain unchanged at 30g per dmt and 350g per dmt respectively.

Fastmarkets reserves the right to exclude outlier or incomplete data. Therefore, were Fastmarkets to adopt a normalization process for gold and silver, bids, offers and trades reported to Fastmarkets without sufficient detail on gold and silver credits needed for normalization could be discarded.

This proposal follows a public consultation opened on February 3, which you can find at this link.

The feedback period for this proposal will end on May 22, 2026.

To provide feedback, or if you would like to provide price information by becoming a data submitter to these prices, please contact pricing@fastmarkets.com and basemetals@fastmarkets.com by May 22, 2026. Please add the subject heading “re: Copper Concentrates TC/RC Index.”

Please indicate if comments are confidential. Fastmarkets will consider all comments received and will make comments not marked as confidential available upon request.

To see all Fastmarkets’ pricing methodology and specification documents, go to the Fastmarkets methodology page.