The news pushed shares of MGM Mirage up as much as 17% in aftermarket trading. MGM responded to the filing by saying that its board would begin considering the proposal at a meeting following Tuesday's shareholder meeting "and will respond in due course."

MGM is the world's second-largest casino company, thanks to its acquisition of Mandalay Bay Resort Group in 2005. All told, MGM now controls 865 acres and 10 casinos along Las Vegas Boulevard with three miles of Strip frontage. Its jewel is the Bellagio, but not for long. Next door, it is developing the $7.4-billion CityCenter project, which got under way this time last year. The first phase of the integrated resort development will include a 4,000-room luxury hotel and casino, two 400-room non-gaming hotels, 2,900 condominium units and 500,000 sf of commercial space.

Last week, MGM Mirage completed its 33.5-acre land acquisition at the north end of the Strip by paying $444 million for 25.5 acres at the corner of Las Vegas Boulevard and Sahara Ave. The smaller part of the deal, eight acres at Circus Circus Drive and the Strip for a total of $131 million, closed earlier this month. The two parcels connect to each other as well as MGM's existing assets there, which include the Circus Circus casino resort, giving the company 102 acres on which to master plan another integrated resort.