And now, speculation on Mulally speculation

There are several theories on Mulally's timing.

Alan Mulally ended months of speculation that he will leave Ford to replace Microsoft CEO Steve Ballmer. Now there is speculation about the end of all the speculation.

Mulally, 68, had never quite denied that he might go to Microsoft during all those months, but he told the Associated Press last week that he will remain at Ford through at least this year.

"I would like to end the Microsoft speculation because I have no other plans to do anything other than serve Ford," he said in an interview.

According to one theory, Mulally's statement was motivated by a desire not to divert attention from the launch of the redesigned F-series pickup at the Detroit auto show this week. Another possible factor: Ford's frustrated board of directors got tired of the distraction and insisted Mulally put an end to the conjecture.

And finally there was talk that Microsoft had simply fallen out of love with the idea of hiring Mulally. There were reports that his candidacy had faded amid concerns about his age and lack of technology experience.