Analysis: The US copper mountain, and what it could mean for UK scrap prices

Copper has been pulled into US warehouses for 18 months on the threat of import tariffs. This week the pile showed up in London, where LME stocks hit their highest level since July and copper fell to a five-week low. The price outlook now depends on a tariff decision that may never come.

What’s happened

Washington has had a copper tariff study running since February 2025. Semi-finished copper already carries a 50% tariff, but refined copper was exempted, and that exemption is under review. Traders have been moving refined metal into the US ahead of a possible change. The US warehouses of the Comex exchange now hold more than 714,000 tonnes, up almost 750% since the end of February 2025, and hold roughly 70% of the world’s visible copper stocks. That drained stock elsewhere and helped push LME copper up around 17% this year.

The pull is now fading. The price gap between US and London copper has narrowed sharply from its mid-2025 peak, so there’s less incentive to ship metal across the Atlantic, and more is now arriving in LME warehouses. LME stocks rose for a fourth straight session on Thursday and are up about a fifth on the week. Around 62% of that metal sits in US locations. Copper fell almost 2% on Thursday, then bounced on Friday.

Key dates

• 30 June 2026: the deadline for the Commerce Department’s updated recommendation on refined copper. No decision has been announced.
• 1 January 2027: the date from the original proposal for a 15% tariff on refined copper imports.
• 2028: the proposal rises to 30%.
• Early December: one analyst expects pressure on prices as the window for clearing metal through US customs ahead of January narrows.

Why it matters for the UK

UK yards and buyers price scrap off the LME, not Comex. So when metal drains out of London, prices tighten. When it flows back, they ease. The warehouse stocks and the policy deadline are now a bigger driver of copper than demand in the UK. One analyst quoted this week says Washington letting January pass without a decision is the most likely outcome. If so, expect the US premium to keep narrowing and more metal to come back to London.

What it means for yards and buyers

• Expect swings, not a one-way move. Copper is still well up on the year, but a stock build and a missed tariff deadline both point to volatility into December.
• Don’t hold stock on a tariff bet. Nobody, including the analysts, knows what Washington will do. Selling steadily beats waiting for one decision.

Sources: Trump tariff threat built a US copper mountain, but the effects are fading (14 Oct) · Copper rebounds as inventories, stock markets stabilise (23 Oct) · Copper price falls to five-week low as LME inventory build continues (22 Oct) · What’s next for US copper import tariffs (12 Jun)