Operations & financial report

Interest rates

Rio Tinto's interest rate management policy is generally to borrow and invest at floating interest rates. This approach is based on the historical correlation between interest rates and commodity prices. In some circumstances, an element of fixed rate funding may be considered appropriate. Rio Tinto hedges interest rate and currency risk on most of its foreign currency borrowings by entering into cross currency interest rate swaps in order to convert fixed rate foreign currency borrowings to floating rate US dollar borrowings. At the end of 2007, US$4.9 billion (2006: U$1.2 billion) of the Group's debt was at fixed rates after taking into account interest rate swaps and finance leases. Based on the Group's net debt at 31 December 2007, the effect on the Group's net earnings of a half percentage point increase in US dollar LIBOR interest rates with all other variables held constant, would be a reduction of US$158 million. These balances will not remain constant throughout 2008, however, and therefore these numbers should be used with care.