Los Angeles (Reuters) - MGM Mirage reported a fourth-quarter loss of USD 1.15 billion on Tuesday as gambling demand declined, and it wrote down impaired assets, sending its shares down 3 percent in extended trade. The No. 2 casino operator also said its banks had agreed to waive debt covenants through May 15. MGM, grappling with weak demand from recession-weary consumers and a credit market crisis, warned earlier in March that auditors had substantial doubt about the company's ability to continue as a going concern.