Bloomberg Copper rose in a volatile trading session, with London Metal Exchange futures jumping on their reopening after the Christmas holiday, extending a strong end-of-year rally as global availability tightened. Prices increased as much as 6.6% in the initial minutes of trading — the biggest intraday gain since 2022 — to near $13,000 a ton, before later retreating to trade about 1.6% higher by mid-afternoon in London. New York futures fell, erasing much of Friday’s 5% gain while the LME was closed. ...