Justin Lahart has a new article about research in the works on top earners, here is one relevant snippet:
The economists have also been looking into what’s going on with the top 0.1%, while digging more deeply into incomes for specific occupations. In a preview of this work he presented at the American Economic Association’s annual meeting last month, Mr. Guvenen showed that over the past 30 years income cyclicality for this group has risen substantially relative to the population at large.
That is largely a result of a change in the composition. It used to be that doctors — a group with very little income cyclicality — represented about a quarter of top 0.1%. Now they account for less than a tenth. Filling the gap, a bigger share of people in finance-related occupations.
The underlying research you will find here. For the pointer I thank Ray Lopez.