Ubs, the giant swiss bank, has raised its estimated losses due to alleged unauthorised trading to $2.3bn (£1.5bn) from an initial $2bn.

The bank also said the alleged activity by trader from Ghana Kweku Adoboli was uncovered after UBS began making inquiries.
That prompted Mr Adoboli to admit the losses on Wednesday, UBS said. The trader was charged with fraud and false accounting at a London court on Friday.
The bank’s statement comes as UBS boss Oswald Gruebel insisted he would not resign over the incident.
“I’m responsible for everything that happens at the bank,” Mr Gruebel told Swiss Sunday newspaper, der Sonntag. “if you ask me whether I feel guilty, then I would say no.”
‘Fictitious’ hedges
Mr Adoboli has been remanded in custody until a committal hearing on 22 September.
According to the charges, the fraud took place between January and September this year.The charges add that Mr Adoboli filed false accounts between October 2008 and December 2009, and from January to September 2011.
However, UBS latest statement said the losses only related to trading positions taken on in the last three months.
The 31-year-old worked for UBS’s global synthetic equities division, buying and selling exchange traded funds, which track different types of stocks or commodities such as precious metals.
Prosecutors say Mr Adoboli “dishonestly abused that position intending thereby to make a gain for yourself, causing losses to UBS or to expose UBS to risk of loss”.
The UBS statement claimed Mr Adoboli had conducted legitimate derivative transactions, giving the bank heavy exposure to various stock market indexes.
But he had then entered “fictitious” hedges against these positions into UBS’ risk management system, while in reality he had no hedge in place and was breaching the risk limits that the bank required him to work within.
Stock markets have fallen 10%-20% in the past two months on growing fears of a renewed recession in the US and a disorderly debt default by Greece.
“Following inquiries directed to him by UBS control functions that were reviewing his positions, the trader revealed his unauthorized activity on September 14, 2011,” the UBS statement said.
The bank said it was now operating within normal risk limits, implying that the unauthorised positions had been hedged or unwound.

Nigerian security forces killed at least 23 people in the northeastern city of Maiduguri in retaliation for a bomb attack blamed on a radical Islamist sect, Amnesty International said on Monday.
Boko Haram, a radical group which wants sharia law more widely applied across Africa’s most populous nation, has been behind almost daily shootings and attacks with homemade bombs in and around Maiduguri, the capital of Borno state.
Saturday’s attack near a market in the centre of the city injured three soldiers and killed several civilians, authorities and witnesses said.
Maiduguri residents have accused members of a military Joint Task Force (JTF) of using indiscriminate force when reacting to attacks carried out by Boko Haram. The government says there have only been isolated incidents of misbehaviour by officials.
“House to house searches, brutalisation, unlawful arrests, killings and disappearances have been the operating practice in Maiduguri for some months now,” said Tawanda Hondora, Amnesty International’s Deputy Director for Africa.
“Unless steps are taken to ensure security forces operate within the law and respect human rights at all times, the next time Boko Haram attacks or kills a soldier, we are likely to see the same thing happen again,” Hondora added.
Thousands of people have fled Maiduguri, the capital of Borno state, in recent weeks, fearing being caught up in clashes between JTF officials and Boko Haram.
More than 250 people have been killed since July 2010 by people believed to be members of Boko Haram, Amnesty International said in a press release on Monday. Attacks usually target police, churches and outdoor drinking areas.
Bomb blasts in the north have replaced militant attacks on oil facilities hundreds of kilometres (miles) way in the southern Niger Delta as the main security threat in Nigeria. The United States and European Union have condemned the violence.
Boko Haram strikes have spread farther afield in recent months, including a bomb in the car park of national police headquarters in the capital, Abuja, last month.
The group’s views are not espoused to by the majority of Nigeria’s Muslim population, the largest in sub-Saharan Africa.