Case Study · CME/LME Copper · June 26–27, 2026

Anatomy of a $600/ton Copper Spread

The CME/LME copper spread hit ~$600/tonne this week. Our subscribers got the alert. Here's what the window looked like and why it opened.

Spread Peak $600+/t

Alert Fired Jun 26 · 09:42 UTC

Window Open ~18 hours

Trigger Commerce Dept. tariff filing

1. The Setup

On June 26, 2026, the U.S. Commerce Department submitted its refined copper tariff recommendation to the President — the final step before a potential phased tariff on copper cathode imports. The CME forward curve priced in significant disruption risk. The LME didn't.

The result: a $600/tonne gap between the two benchmarks — the widest since mid-2025 before the exemption reversal.

This wasn't a data glitch or a one-second flash. It was a fundamentals-driven dislocation that held for 18 hours.

2. The Signal

Spread Crossing $600/tonne — Jun 26 09:42 UTC Alert threshold: $500/t

CME Bid Side

Elevated

LME Ask Side

Subdued

Confirmed By

2 independent feeds

Alert Fired — Subscriber threshold exceeded

Confirmation from two independent data feeds before alert triggered — no false signal

This is what our subscribers saw in real time — the spread widening past their threshold, the CME side climbing, the confirmation from two independent data feeds before the alert fired.

3. The Window

18 hrs

Spread held above $580/tonne

The spread held above $580/tonne for approximately 18 hours before mean-reverting. The trigger was a Reuters report on June 27 indicating refined copper would not be included in the initial tariff tranche — at which point the CME premium compressed by roughly 40% in under 90 minutes.

18 hours. That's the window.

— Arbpilot signal log, Jun 26–27 2026

4. What a $50–200M Desk Would Have Done With It

A desk operating at that scale would have bought LME copper cathode — sourced from South American or Asian producers actively selling into the US arbitrage — and simultaneously entered a CME futures short to lock in the $580–600/tonne spread.

Arbitrage Math — Gross Spread

Gross spread captured $580–600/tonne

Freight (South American / Asian origin) -$30–50/tonne

Financing cost (carry) -$15–20/tonne

Exchange fees (CME + LME) -$5–10/tonne

Net arb (after all costs) ~$500–545/tonne

Hold from alert to confirmation. Exit on the news break.

That's not speculation. That's the window our subscribers saw, in real time, before the majors priced it out.

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