Copper inventory sentiment signalled tightening ahead of Q3 backwardation, Permutable analysis finds

London, LONDON, Oct. 08, 2026 (GLOBE NEWSWIRE) — Copper inventory-related news indicated growing availability concerns almost ten weeks before the London Metal Exchange’s copper market returned to sustained backwardation this summer, according to research published by market intelligence provider Permutable.

Permutable’s copper inventory news sentiment turned on May 13, 2026, almost 10 weeks before sustained LME backwardation returned on July 20. Sources: Permutable and LME, through Oct. 5, 2026.

The analysis found that Permutable’s copper inventory sentiment measure crossed above its trailing-year average on May 13, while LME warehouse stocks remained close to their April peak. Sustained backwardation – when copper for immediate delivery costs more than copper for later delivery – returned on July 20.

The findings offer a retrospective case study of how supply-related news can complement exchange stock data when assessing physical copper availability. They also highlight why the location and accessibility of inventories matter alongside their total volume.

The inventory signal and the summer squeeze

LME copper stocks reached approximately 403,000 metric tons on April 15. When inventory sentiment strengthened on May 13, cash copper still traded at a discount of $43 per metric ton to the three-month contract.

By mid-August, stocks had fallen to approximately 205,000 metric tons, about 49% below their April peak.

The cost of immediate delivery increased sharply over the same period. Cash copper traded at an average discount of approximately $82 per metric ton during February through April, compared with an average premium of approximately $198 in August. The premium reached $535 on Aug. 17, according to the research note.

Permutable’s analysis suggests that changing inventory-related news provided additional information about developing availability pressure while the visible stockpile remained substantial.

Regional availability remains relevant

The report also examines how expectations of possible U.S. refined-copper tariffs encouraged inventory accumulation in American warehouses, reducing availability elsewhere. This geographic redistribution helps explain how substantial copper holdings can coexist with pressure on metal available for immediate delivery in other markets.

As of Oct. 5, LME stocks had recovered to 244,900 metric tons, indicating some relief from August’s tightest conditions. However, the cash premium widened from $35 to $64 per metric ton that day, keeping immediate availability in focus.

Methodology and limitations

The research compares Permutable’s Asset Sentiment Indices with LME copper inventories and cash-to-three-month price spreads, using data through Oct. 5, 2026.

Permutable scores news for its bullish or bearish implications for copper. The thematic measures use a news-flow calculation with a 14-day half-life and are standardized against each theme’s trailing year.

Since January 2024, weekly inventory sentiment has shown a correlation of −0.64 with four-week changes in LME stocks. More bullish inventory coverage was associated with larger stock drawdowns.

The correlation establishes an association, not causation or independently validated forecasting accuracy. The almost ten-week lead describes the May – July 2026 episode and should not be interpreted as a consistent forecasting horizon.

For more information on Permutable’s industrial metals market intelligence, visit permutable.ai/industrial-metals-market-intelligence.

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