Published on: 2026-09-11
Updated on: 2026-09-11
Seeing copper quoted at a higher price in New York than in London can look like an obvious market mismatch. Both contracts settle against high-grade copper, yet they give access to different delivery systems. Once metal has to reach the right warehouse at the right time, the price gap stops looking so strange.
COMEX and LME copper use different contract structures and delivery networks, so you need to adjust headline prices for units and timing before comparing them.
A U.S. premium can emerge when copper available for COMEX delivery becomes more valuable than copper available elsewhere.
Arbitrage keeps the markets connected, although freight, financing, delivery rules and transport time prevent instant price convergence.
A wide COMEX-LME spread can reflect regional scarcity, tariff expectations or delivery pressure without signalling a global copper shortage.
New York copper usually refers to copper futures traded on COMEX, part of CME Group. London copper usually refers to contracts traded on the London Metal Exchange.
The two markets price the same broad commodity, but their contracts are structured differently.
Feature |
COMEX Copper |
LME Copper |
Standard contract |
25,000 lb |
25 tonnes |
Quotation |
U.S. cents per pound |
U.S. dollars per tonne |
Delivery system |
Approved U.S. warehouses |
Global warehouse network |
Different quotation units can make prices look far apart when they are actually close. One metric tonne equals about 2,204.62 pounds, so COMEX copper at $5.00 per pound is equivalent to roughly $11,023 per tonne.
Timing also has to match. COMEX uses listed futures months, while the LME uses a prompt-date structure that includes daily, weekly and monthly delivery dates.
A useful comparison therefore requires two adjustments. Convert both prices into the same unit, then compare contracts with similar delivery periods.
Copper trades globally, but physical supply remains tied to location.
Metal available in Europe, Asia or South America cannot immediately satisfy demand for copper deliverable through the U.S. exchange system. If eligible American supply becomes tight, COMEX can develop a premium even while copper remains readily available elsewhere.
Physical copper transactions often start from a benchmark price and add a regional premium reflecting local availability and the cost of getting the metal where it is needed.
A simplified relationship is
U.S. copper value ≈ global benchmark + regional supply premium
The size of that premium depends on how easily the market can source suitable copper in the United States.
Copper can therefore be plentiful globally and scarce where delivery is actually required.
A large spread appears to create an obvious trade. Buy copper where it is cheaper, move it to the United States, and sell it at the higher COMEX price. That trade only works when the premium covers the full cost and risk of moving the metal.
Those costs can include
ocean and inland freight
insurance
financing
storage and handling
import duties
warehouse and delivery expenses
price risk while the copper is in transit
A $200 or $300 per tonne premium may disappear once you include those expenses. This creates an effective arbitrage band. COMEX and LME prices do not need to match exactly as long as the difference remains too small to justify relocating physical copper.
Time adds another constraint. Futures prices can respond almost immediately to a change in supply expectations. Copper cathodes still have to travel by ship, rail or truck and pass through ports, customs and warehouses.
Markets can move money instantly but not thousands of tonnes of copper instantly. A sufficiently large premium can eventually attract shipments toward the U.S., yet the spread may remain wide while that copper is still on its way.
The amount of copper in the world is different from the amount available for immediate futures delivery. Both COMEX and the LME impose standards on metal delivered against their contracts. Eligible copper must meet requirements covering factors such as
grade and quality
approved producers or brands
warehouse location
quantity
availability by the required delivery date
Metal can therefore exist somewhere in the supply chain without being usable against a nearby futures obligation.
May 2024 provided a sharp example. COMEX copper traded more than $1,000 per tonne above LME copper at one stage as short positioning collided with limited immediately deliverable supply. Trading firms began redirecting physical copper toward the United States, although shipments could not resolve the near-term shortage overnight.
The episode showed that a New York premium does not require tariffs. Delivery constraints and futures positioning can produce one on their own.
Tariffs add another potential cost to supplying copper to the United States. If the market expects imported refined copper to face a future duty, relevant COMEX contracts can begin reflecting the higher expected cost before the tariff takes effect.
The wider premium can then encourage firms to bring copper into the country while existing trade terms still apply. That pattern appeared during 2025. Expectations of new U.S. copper tariffs widened the COMEX-LME spread and helped draw refined metal into U.S. warehouses.
The policy announced in July ultimately imposed a 50% tariff on specified semi-finished copper products and copper-intensive derivatives, while leaving refined copper outside the immediate levy. Once the expected cost advantage changed, part of the premium unwound.
The episode illustrates how quickly expectations can alter physical flows. The threat of a tariff can redirect copper before the tariff changes the cost of an imported tonne.
The spread provides information that a single copper price cannot.
Spread movement |
What it may indicate |
COMEX premium widens |
Tighter U.S. supply or higher expected import costs |
Spread jumps quickly |
Delivery pressure or short covering |
Premium narrows |
Incoming supply or easing regional scarcity |
COMEX falls below LME |
Earlier U.S. premium has lost support |
No single interpretation works in every case. Inventory, trade policy and futures positioning can affect the spread at the same time.
It is also useful to separate geographical spreads from time spreads. The COMEX-LME spread asks where copper is relatively expensive. Contango and backwardation describe whether copper for later delivery is priced above or below nearby delivery.
No. COMEX can trade above, close to or below an equivalent LME price. The relationship changes with regional supply, inventories, import costs, delivery conditions and positioning.
Not necessarily. A wide premium can reflect tight availability inside the U.S. delivery system while copper remains available elsewhere. Regional scarcity and global scarcity are different conditions.
Only if the metal satisfies COMEX delivery requirements and the economics justify the move. Brand eligibility, transport, financing, storage, duties and timing can absorb much of the apparent price advantage.
Copper may trade globally, yet the physical metal remains tied to warehouses, ports, shipping routes and exchange delivery rules. COMEX can therefore rise above LME when eligible copper in the United States becomes more valuable or more expensive to obtain. When that premium becomes large enough, arbitrage attracts metal toward the higher-priced market and helps bring the two benchmarks back toward each other.
