Personally?
Which of these retired?

>I know of several.
>
>- Jim McNerny at 3M. Left to be CEO at Boeing. His background was airlines.
>- Andy Grove at Intel (due to illness).
>- The CEO of NPR here in the US just resigned to run National Geographic.
>- Michael Bloomberg left the company he founded run for mayor of New York City
>- Mitt Romney
>- Meg Whitman left EBay to run for Governor of California
>- Hank Paulson left Goldman Sachs to be US Secretary of Treasury
>
>>Unfortunately, there's no fact you can get for sure from this kind of situation.
>>
>>What I know for sure is how friends of mine had to leave their top management positions in large corporation; I never knew of a single example where they resigned by their only own will.