The price premium between U.S. COMEX copper futures and London Metal Exchange prices is becoming a real-time gauge of potential tariffs on refined copper:
Societe Generale estimates that the current premium implies a 14.6% chance of a 15% tariff in January 2027 and a 37% chance of a 30% duty in January 2028:
A 12-year high in U.S. copper inflows has supported prices as traders await a final White House decision on further levies:
One specialist arbitrage trade on a metal commodity is evolving into a real-time gauge of U.S. tariff risk.
Copper — seen as a broader economic barometer, with the industrial metal a key component in construction, electronics, and transportation — has been on a tear for more than a year, with futures reaching a record high of almost $6.90 per pound last week:
The spread between U.S. COMEX futures and London Metal Exchange prices has historically been used by physical traders, banks, hedge funds, producers, and consumers to profit from temporary price differences and hedge against price risk between the two markets:
Now, though, Societe Generale analysts say the trade has been upended by the prospect of fresh Section 232 tariffs on refined copper, pending a White House investigation:
The U.S. already charges a 50% levy on imports of semi-finished copper products and certain other products made with copper.
Copper tariff forecasts
To translate the spread into tariff odds, SocGen modeled the cost of moving LME-grade copper from European warehouses to the U.S. East Coast and compared that all-in delivered price with COMEX futures:
Analysts said the current COMEX premium over fully delivered LME metal implies a 14.6% likelihood of the Commerce Secretary's recommended phased universal tariff of 15% by January 2027:
That rises to a 37% probability of a 30% duty by January 2028:
A wider premium remains supportive for copper prices near term, particularly as mine supply remains tight and competition for available metal between the U.S. and China intensifies.
