Metro-Goldwyn-Mayer ( MGM) was higher Thursday amid indications a bidding war is breaking out for the movie studio. The shares were recently up 70 cents, or 5.8%, to $12.80 after media reports said Time Warner ( TWX) was weighing a bid to compete with Sony's ( SNE) $5 billion offer for MGM. Despite a five-month effort to buy the studio by Sony, the stock dropped back into play on Tuesday when MGM executives told a shareholders meeting that they were considering additional alternatives for the company. According to the reports, Time Warner is considering a bid that would pay MGM's 77%-owner, the Las Vegas billionaire Kirk Kerkorian, with a series of unregistered stock and will pay remaining public shareholders in cash. Time Warner is said to be starting due diligence on the acquisition and plans to take its time, given the cursory vetting it gave in the AOL acquisition four years ago. Sony's existing offer, which is being pursued along with private equity firms Texas Pacific Group and Providence Equity Partners, includes about $1.9 billion in debt and comes out to roughly $13 a share. Meanwhile, the New York Post reported Thursday that Microsoft ( MSFT) has also expressed interest in MGM. Citing sources, the newspaper said Microsoft's "interest seems to be coming from high levels inside the company."