Goldman Sachs Group Inc. predicted a rally in commodities from iron ore to gold will falter and forecast copper and aluminum prices will slide as much as 20 percent over the next year. Any increase in raw material prices will prompt more supplies to enter the market, making it difficult for any advance to be sustained, analysts including Jeffrey Currie wrote in a report dated March 7. The bank maintained its bearish outlook for gold, said iron ore’s surge would prove temporary and reiterated that oil will fluctuate between $20 and $40 a barrel. Goldman also said it was a good time to make bets that copper and aluminum would decline. “Higher prices are much harder to sustain in a supply-driven market since supply is primed to return with higher prices,” the analysts wrote in the report. “But this lesson will likely only be learned through false starts.” Iron […]