Corrected prices and scope
For November 4, Fastmarkets revised the index to $396.34 per dry metric tonne (dmt) from the originally published $395.93 per dmt. The November 6 value was corrected to $403.99 per dmt from $401 per dmt.
The notice's statement that inferred prices were unaffected refers to a separate set of calculated values. Fastmarkets' November 2025 alumina methodology describes inferred prices for Indonesia, Vietnam and India as calculations that apply the relevant assessed netback rate to the daily FOB Australia alumina index.
Under that methodology, Fastmarkets limits retrospective revisions to administrative or calculation errors. An incorrectly published index must be corrected and republished as soon as possible, with subscribers receiving a correction notice.
Benchmark use and specifications
The FOB Australia alumina index also serves as a settlement price on global exchanges, according to Fastmarkets' methodology. Its published values therefore have a role beyond the physical spot market.
The MB-ALU-0002 specification covers smelter-grade alumina containing at least 98.5% Al2O3, in quantities of at least 5,000 tonnes. The delivery basis is fob Bunbury/Kwinana, Australia, with other Pacific origins normalized to that basis and timing within two months.
Prices are quoted in U.S. dollars per dry metric tonne, with payment due 30 days after loading. Fastmarkets publishes the index daily at 4 p.m. London time, and its data history begins in August 2010.
October market context
The corrections follow an increase in the index during October. In an LME Week preview published October 14, 2026, Fastmarkets put the preceding Friday's daily FOB Australia alumina index at $367.96 per tonne, compared with $351.53 per tonne a month earlier.
Separately, Westpac's October 2026 commodities update reported alumina prices above US$380 per tonne at the start of October. It attributed the rise to higher freight costs and production cuts at key suppliers.
Westpac said Alcoa had cut its 2026 alumina production guidance by 200-300 kt following operational disruptions at one of its Western Australian refineries. Alunorte had reduced output by 100-120 kt after earlier gas-supply disruptions, the bank said.
Comments and data submissions
Fastmarkets directed questions and feedback about the correction, as well as inquiries about becoming an index data submitter, to its pricing and base metals teams by email. It asked senders to use the subject line "re: Alumina indices." and identify any confidential comments.
The company said it would consider every comment received. Comments not designated confidential will be available on request.
