Cutting jobs on Wall Street isn't working — here's what could really lower costs

Wall Street banks require major surgery.
The slump in several key businesses this year — from trading to deal underwriting — has been well documented.
But a new study on the industry, from the consulting group McKinsey, points to a much longer-term problem with their performance — and specifically with their cost structure.
It makes for grim reading.
The top 10 banks posted a combined return on equity, a key measure of performance, of 7% in 2015, according to McKinsey. That's b