The purchase: Alcan Inc. for $38.1-billion (U.S.) in 2007.
The problem: Rio Tinto paid top dollar for Alcan at the peak of the commodity cycle. Demand slowed and aluminum prices slumped.
The writedown: $14-billion last month. The aluminum portion of the charge, roughly $11-billion, raises Rio’s total Alcan writedown to about $30-billion, or almost 80 per cent of the purchase price.