The Commodity Had a Price. The Grade Did Not Exist in the Market.
Quote from chief_editor on June 14, 2026, 5:30 pmCommodity grades that are infrequently traded have published prices but limited market depth. Selling in size in an illiquid grade market creates price impact that published prices do not predict.
A mining company that had accumulated inventory of a specialty ferro-alloy — high-carbon ferromanganese, 75% Mn grade — found that published price assessments for the material showed a spot price of approximately $1,200 per tonne. The inventory was 1,800 tonnes. At $1,200, the inventory was worth $2.16 million.
When the company began selling the inventory — through a metals trading intermediary — they discovered that the market for 1,800 tonnes at that grade, in the relevant market, was not deep enough to absorb the volume at the published price. After placing the first 400 tonnes at prices close to the assessment, subsequent volume pushed the available buyers toward lower bids. The final 600 tonnes cleared at approximately $980 per tonne — $220 per tonne below the opening price.
Weighted average realized price across the 1,800 tonnes: approximately $1,095. Difference from published assessment: $105 per tonne, $189,000 in total. The assessment price was accurate for the small volume that was last traded in the market. It was not an accurate predictor of what 1,800 tonnes would realize.
Published Price Assessments Are Not Market Depth Measurements
Commodity price assessments — from Platts, Metal Bulletin, Fastmarkets, Argus — are estimates of the market-clearing price for a standard volume at the time of assessment. They are based on the prices of recent transactions, bid and offer indications from market participants, and methodology-based corrections. They represent the price at which a "standard" quantity can be traded.
What constitutes a "standard" quantity varies by commodity and grade. For major LME metals — copper, aluminum, zinc — a standard quantity may be thousands or tens of thousands of tonnes, and the market is deep enough that price assessments are reasonably predictive of what actual volumes will realize. For specialty ferro-alloys, minor metals, or niche grades within major commodity categories, the "standard" volume may be small — a few hundred tonnes — and the market depth for larger volumes is limited.
A trader or company holding inventory in an illiquid grade that exceeds the market's typical absorption capacity cannot sell at the published price without impacting the market — their own selling activity changes the price they realize. The larger the position relative to typical market turnover, the larger the price impact.
Industry estimates for price impact in specialty ferro-alloy markets suggest that selling volumes representing more than 10 to 15% of monthly traded volume in a specific grade can produce realized prices 5 to 20% below the published assessment, depending on the elasticity of demand at that time and the availability of substitute grades. The impact is front-loaded — the first tranches clear near the published price, subsequent tranches at progressively greater discounts as the available buyer pool is depleted.
The Inventory Valuation Problem
For companies that hold commodity inventories of niche grades — mine operators, specialty chemical producers, industrial consumers with surplus inventory — the gap between published price assessment and realizable value in size is a valuation question as well as a commercial one.
Financial statements that value commodity inventory at published assessment prices may overstate the realizable value if the inventory volume exceeds the market's absorption capacity. Auditors and analysts who rely on published prices to assess inventory values without considering market depth are accepting an assumption that may be materially incorrect for niche grades.
The commercial and financial reality is the same: the inventory is worth what the market will actually pay for it at the point in time it needs to be sold, and that value may be materially less than the last published price assessment. The gap between the assessment and the realized value is discovered when the inventory is actually sold — which may be when cash is needed urgently, when the position needs to be liquidated for balance sheet reasons, or when the trading relationship that creates demand for the material ends. None of these are comfortable moments to discover that the asset was worth 88 cents on the dollar.
Commodity grades that are infrequently traded have published prices but limited market depth. Selling in size in an illiquid grade market creates price impact that published prices do not predict.
A mining company that had accumulated inventory of a specialty ferro-alloy — high-carbon ferromanganese, 75% Mn grade — found that published price assessments for the material showed a spot price of approximately $1,200 per tonne. The inventory was 1,800 tonnes. At $1,200, the inventory was worth $2.16 million.
When the company began selling the inventory — through a metals trading intermediary — they discovered that the market for 1,800 tonnes at that grade, in the relevant market, was not deep enough to absorb the volume at the published price. After placing the first 400 tonnes at prices close to the assessment, subsequent volume pushed the available buyers toward lower bids. The final 600 tonnes cleared at approximately $980 per tonne — $220 per tonne below the opening price.
Weighted average realized price across the 1,800 tonnes: approximately $1,095. Difference from published assessment: $105 per tonne, $189,000 in total. The assessment price was accurate for the small volume that was last traded in the market. It was not an accurate predictor of what 1,800 tonnes would realize.
Published Price Assessments Are Not Market Depth Measurements
Commodity price assessments — from Platts, Metal Bulletin, Fastmarkets, Argus — are estimates of the market-clearing price for a standard volume at the time of assessment. They are based on the prices of recent transactions, bid and offer indications from market participants, and methodology-based corrections. They represent the price at which a "standard" quantity can be traded.
What constitutes a "standard" quantity varies by commodity and grade. For major LME metals — copper, aluminum, zinc — a standard quantity may be thousands or tens of thousands of tonnes, and the market is deep enough that price assessments are reasonably predictive of what actual volumes will realize. For specialty ferro-alloys, minor metals, or niche grades within major commodity categories, the "standard" volume may be small — a few hundred tonnes — and the market depth for larger volumes is limited.
A trader or company holding inventory in an illiquid grade that exceeds the market's typical absorption capacity cannot sell at the published price without impacting the market — their own selling activity changes the price they realize. The larger the position relative to typical market turnover, the larger the price impact.
Industry estimates for price impact in specialty ferro-alloy markets suggest that selling volumes representing more than 10 to 15% of monthly traded volume in a specific grade can produce realized prices 5 to 20% below the published assessment, depending on the elasticity of demand at that time and the availability of substitute grades. The impact is front-loaded — the first tranches clear near the published price, subsequent tranches at progressively greater discounts as the available buyer pool is depleted.
The Inventory Valuation Problem
For companies that hold commodity inventories of niche grades — mine operators, specialty chemical producers, industrial consumers with surplus inventory — the gap between published price assessment and realizable value in size is a valuation question as well as a commercial one.
Financial statements that value commodity inventory at published assessment prices may overstate the realizable value if the inventory volume exceeds the market's absorption capacity. Auditors and analysts who rely on published prices to assess inventory values without considering market depth are accepting an assumption that may be materially incorrect for niche grades.
The commercial and financial reality is the same: the inventory is worth what the market will actually pay for it at the point in time it needs to be sold, and that value may be materially less than the last published price assessment. The gap between the assessment and the realized value is discovered when the inventory is actually sold — which may be when cash is needed urgently, when the position needs to be liquidated for balance sheet reasons, or when the trading relationship that creates demand for the material ends. None of these are comfortable moments to discover that the asset was worth 88 cents on the dollar.