JPMorgan Chase & Co., the largest U.S. bank by assets,restated first-quarter results to reduce net income by $459 millionafter a review of the firm's chief investment office found thatemployees may have hid losses.

Net income was $4.92 billion, rather than the $5.38 billionpreviously reported, the New York-based bank said today in aregulatory filing. The CIO was responsible for trading losses thatthe bank estimated at $2 billion in May.

“Recently discovered information raises questions about theintegrity of the trader marks, and suggests that certainindividuals may have been seeking to avoid showing the full amountof the losses being incurred in the portfolio during the firstquarter,” the bank said.