Wall Street's most important business is bouncing back

The crash of fixed income, currencies, and commodities trading has been Wall Street's never-ending story.
Over the past few years, revenue has plunged, traders have been fired, and business lines have been shuttered.
But for at least a moment, that pressure seems to have abated.
On Friday, both JPMorgan and Citigroup reported a knockout quarter in the business in the third quarter.
For its fixed-income unit, JPMorgan reported revenue of $4.33 billion for the quarter — up 45% from the same