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.
What is the relationship between 'Xbox' and 'Microsoft' in the context of the input sentence.
Options: owned by, chief executive officer, currency, employer