Societe Generale analysts note that the widening price spread between U.S. COMEX and London Metal Exchange (LME) copper futures has become a real-time indicator of potential U.S. tariffs. Their model suggests the current COMEX premium implies a 14.6% likelihood of the Commerce Department's recommended 15% tariff on refined copper by January 2027, increasing to a 37% probability for a 30% duty by January 2028. The Commerce Department has recommended a phased universal tariff, pending a White House investigation, as U.S. policymakers are increasingly concerned about reliance on imported refined copper.