Analysts at JP Morgan have reversed earlier forecasts on the health of investment banks with strong credit trading businesses in 2012, warning that revenues from fixed income, currencies and commodities could be set to fall by almost a third.

The analyst team, led by Kian Abouhossein, published a note late last week in which it predicted that combined revenues from the FICC units at some of the world's biggest investment banks could fall by as much as 32% to $15bn in the second quarter of the year.