On the diversifier's fallacy,..............

................the winner's curse, and other stuff you should think about.

"The diversifier’s fallacy is a generalisation of the Peter Principle: individuals rise within an organisation until they are given a job they are not competent to do. Companies diversify until they are engaged in businesses in which they have a competitive disadvantage relative to incumbents. This seems particularly common among financial companies."

-John Kay, as culled from here