@phbz It's not really a rumor, as logically - it's not really a possibility.
I think there was laws passed last year in Japan that stoped foreign companies buying or limiting investment in Japanese ones.
Even if there isn't - SEGA is owned by potentially millions of people, and MS would have had to tender a buyout offer or announce intention to buy out a majority share. You can't do this "secretly" as it's public information.
You don't announce a takeover of a publicly traded company with a controller color and a T-shirt, you file with the SEC.