According to S&P Global, a world's leading provider of credit ratings, said that the sale of BHP’s oil and gas business in a merger with Woodside Petroleum, an Australia-based petroleum company, might lead to a less diversified portfolio and thereby increasing the dependence on iron ore.

Therefore, BHP’s credit rating might be downgraded by two notches from A to BBB+, which will be the lowest rating since the first time being rated in 1995.