July 24 (Bloomberg) — Trading surges that temporarily boostedthe value of credit derivatives held by JPMorgan Chase & Co.may provide clues about whether traders at the bank masked lossesthat have spiraled to $5.8 billion.

Spikes in late January and again at the end of February, whichmore than doubled the volume of trades in an index tied to thecreditworthiness of companies, lowered the cost of the index,raising the value of the bank's holdings. The surges came justbefore end-of-the-month bank audits to verify prices.

The trading patterns offer a road map for investigators afterthe biggest U.S. bank by assets restated first-quarter earnings toaccount for a larger loss on the derivatives than previouslydisclosed. JPMorgan, which shut the London-based groupresponsible for the trades in its chief investment office, said aninternal probe found evidence, without providing specifics, thatemployees may have tried to hide losses.