Swiss banking giant UBS on Sunday revised losses due to rogue trading upwards to $2.3 billion, saying they arose from unauthorised speculative trading in S&P500, DAX and EuroStoxx index futures.
The bank said the true magnitude of the risk exposure on these positions were hidden through "fictitious" positions allegedly executed by the trader.
On Thursday, the bank had estimated that $2 billion were lost in unauthorised trades, hours after 31-year-old Kweku Adoboli was arrested in London on suspicion of the fraud.
The bank reiterated that no client positions had been affected by the unauthorised trades carried out over the last three months.
It has also unwound the action and brought the situation under control.
"We have now covered the risk resulting from the unauthorized trading, and the equities business is again operating normally within its previously defined risk limits," it said.
The bank also revealed that Adoboli had revealed the rogue trades on September 14, after inquiries from the bank's control functions.
An internal probe has been launched on the case and on the bank's control environment, added UBS.