Update: August 4, 2015. Jim Murren just said on the MGM 2nd quarter earnings call that "The Mirage is not on the market." While a property can't be on the market if it's already sold, it's looking more and more like the below report was just a rumor and unlikely to happen.
The Mirage has been sold to Starwood Capital Group - although the official announcement won't be made for a few weeks according to a Las Vegas Advisor report.
LVA is also reporting that Paragon Gaming will operate the casino once the deal is complete.
MGM Resorts International is the parent company of The Mirage. They have been selling off a number of assets recently, including exiting the Reno market by selling Circus Circus Reno and Silver Legacy a few weeks ago.
The question is WHY is MGM selling assets?
This could be a shot in the dark but my guess is Japan. There have been a few rumblings recently about Japan possibly opening up for gambling. Las Vegas Sands CEO Sheldon Adelson and Boyd CEO Keith Smith have both made comments about Japan within the past week.
MGM has their own Japan ties - as the Bellagio fountains will be hosting a Japanese Kabuki performance in August. An MGM co-sponsored Kabuki festival is also being planned for Las Vegas in 2016.
Even if Japan isn't the reason for selling assets - MGM currently has the $1.2 billion MGM National Harbor starting construction, along with Massachusetts and Macau projects underway - so the extra cash from the Mirage sale will be put to good use either way.