Swiss bank UBS said on Sunday it had lost $2.3 billion from unauthorised speculative trades in various equity futures it discovered on Wednesday and has now covered the resulting risk with its equities business again operating normally.

The loss resulted from unauthorized speculative trading in various S&P 500, DAX, and EuroStoxx index futures over the last three months, UBS said in a statement.

The loss arising from this matter is $2.3 billion. As previously stated, no client positions were affected.

UBS trader Kweku Adoboli was charged with fraud and false accounting dating back to 2008 on Friday, a day after the Swiss bank was plunged into crisis by revealing a $2 billion trading loss.

The fraud is a disaster for the reputation of Switzerland's biggest bank, which has only just recovered from the financial crisis when it had to be bailed out by the state, and has prompted calls for the bank's top managers to step down and for UBS's investment bank to be split off.