Refer to the input text as context and select the correct relationship between 'Xbox' and 'Microsoft' from the available options.
Options: chief executive officer, currency, employer, owned by

Microsoft ( MSFT.O ) added 1.2 percent to $20.76 after the software maker said it sold 28 million units worldwide of its Xbox 360 video game console through the end of 2008, extending the Xbox's lead over rival Sony Corp's ( 6758.T )( SNE.N ) PlayStation 3.
owned by