The revaluation was prompted by the company's decision to discount the prices of its 2,400-unit residential inventory by 30%. "This decision and related market conditions led to the conclusion that the carrying value of the residential inventory is not recoverable," MGM said in a statement.

CityCenter is a 50-50 joint venture of MGM Mirage and Dubai World. MGM said Tuesday it would take a $1.15-billion non-cash impairment charge in the third quarter related to its 50% portion of the lost value -- $955 million for the commercial portion of the project and $174 million for the for-sale residential portion of the development.

Earlier this year the original total investment value was $8.7 billion. Back out $1.8 billion in debt, which was restructured and lowered from $2.5 billion in May, and there's $6.9 billion of investment value for MGM Mirage and Dubai World. Due to the lower value of the real estate as estimated by several third party experts, MGM Mirage believes that investment value has fallen to $4.88 billion, or $2.44 billion each. As of June, MGM Mirage had invested $3.5 billion in the project.