S&P warns of potential ratings downgrades at some of the world’s biggest gold miners as they struggle to escape rising debt. Barrick Gold (ABX -2.1%), burdened by a huge debt load and the highest exposure to project cost overruns in the industry, is most at risk of a possible downgrade, S&P says; Goldcorp (GG -1.4%) likely wouldn’t face a downgrade unless the gold price dropped by 50%.