JP Morgan Chase, the US's largest bank, has reported a 6.6% fall in quarterly profits after being hit by legal costs.

The bank paid almost $1bn (£659m) in costs due to a range of investigations into alleged wrongdoing, and has set aside more money to cover bad debts.

JP Morgan's net income was $4.93bn in the fourth quarter, down from $5.28bn for the same period a year ago.

In New York, the bank's shares fell 3.5% in the wake of the results.

The bank has faced both criminal and civil investigations over its currency trading.

Investigations into alleged wrongdoing in currency markets as well as other areas of the bank's business, including the alleged manipulation of Libor interest rates, are still being conducted.

Legal costs for the whole of 2014 were $2.9bn, well below the $11.1bn it paid the year before. It had previously warned that possible losses from all legal proceedings could total $5.9bn (£3.7bn).

Its chief executive, Jamie Dimon, said banks were "under assault".

"We have five or six regulators coming at us on every issue," he said.

The bank set aside $840m in the quarter to cover bad debts, up from $104m in the same period a year earlier.

JP Morgan's revenue from fixed-income trading was down 23% at $2.5bn.

Wells Fargo

Also reporting on Monday was the US's biggest mortgage lender, Wells Fargo.

Its fourth quarter profits edged up slightly to $5.38bn, compared with $5.37bn for the same period in 2013.

Total loans rose 2.8% to $862.6bn. Commercial and industrial lending increased by 15.5% and credit card loans were up 16%.

Mortgage lending was $44bn, down from $50bn in the fourth quarter of 2013.