JPMorgan Chase & Co., the biggest U.S. bank, said it faces a U.S. criminal probe into the firm’s foreign-exchange business and increased the upper end of its “reasonably possible losses” related to legal matters.

The lender is cooperating with a criminal investigation by the Justice Department as well as inquiries by the Commodity Futures Trading Commission and regulators in Britain and elsewhere, the New York-based company said in a regulatory filing. Reasonably possible losses could be as much as $5.9 billion, the bank said, an increase of $1.3 billion since the end of June.

“These investigations are focused on the Firm’s spot FX trading activities as well as controls applicable to those activities,” according to the filing.

Banks are facing probes by authorities on three continents over alleged rigging of currency markets, people with knowledge of the situation have said. Citigroup Inc. and Zurich-based UBS AG disclosed last week that they also face criminal inquiries by the Justice Department into their foreign-exchange businesses. Citigroup restated third-quarter results to include a $600 million legal charge.

Legal expense at JPMorgan in the period was $1.01 billion, tied “in large part” to the currency investigations, Chief Financial Officer Marianne Lake said on Oct. 14. The currency probes could cost banks as much as $41 billion to settle, analysts at New York-based Citigroup, led by Kinner Lakhani, said last month.

JPMorgan shares have gained 4.1 percent this year, trailing the 9.3 percent advance for the 85-company Standard & Poor’s 500 Financials Index.