A blistering turnaround in performance across the board in fixed income, currencies and commodities unit, traditionally Goldman Sachs' chief profit driver, helped power the bank back to profit in the first quarter this year, obliterating market predictions and leaving analysts searching for answers on today's conference call.

One banks analyst had called Goldman's first-quarter figures "a one-off phenomenon", while another said the profits are "not repeatable". HSBC analysts said in a research note: "Powerful, and yet to be fully explained, fixed income earnings offset sagging results just about everywhere else, producing an overall result that was twice as good as the consensus estimate."