[yk]

Class lines are not very defined, and never were, but at least for political analysis the exact boundaries do not matter much. What matters is the difference in influence between the main bodies of the classes.

And while thinking about Marx one needs to keep in mind, that Marx did analyse the mid 19th century economy. Your example of a CEO is actually a quite good one, since a CEO is controlling capital which he does not own, a arrangement that essentially did not exist in the middle of the 19th century. And I think that this split between capital control and ownership of capital is one of the most important theoretical difficulties in applying Marxist analysis to 21st century finance capitalism. The other problem is, that in the 19th century Labor movement the workers had a nuclear option: If the workers just refuse to work, they will be as broke and unemployed as the capitalist they refuse to work for.