Mailing the story:

The world's largest software company, whose stock remains mired around $30, had prepared a multi-pronged assault to try and break into the crucial mobile computing space this year and take Apple Inc and Google Inc down a peg.

But on Monday, it announced a $6.2 billion writedown of a 2007 Internet-advertising acquisition - a reminder that Microsoft has a patchy track record when it ventures outside of its Windows and Office comfort zone.