After 1984 financial sector compensation rose much more quickly than average compensation (The Baseline Scenario). Even if one doesn’t buy all of the associated reasoning the chart deserves an explanation.
The companion Atlantic Article is online early with much more detail. The basic premise is that the US is now a Banana Republic (I think Krugman warned about “turning Argentina” a few years ago), and we aren’t going to clean things up until we overthrow our oligarchy.
It strikes me as too simple, but I hope DeLong and/or Krugman take a whack at it.