LONDON (AFP) -- UBS trader Kweku Adoboli, who gambled away $2.3 billion of the Swiss bank's money, was found guilty of one count of fraud in London on Tuesday.
The jury at Southwark Crown Court was still deliberating on one other charge of fraud and four counts of false accounting between October 2008 and September 2011.
Ghanaian-born Adoboli, 32, who stands accused of Britain's biggest ever fraud, admitted the losses but denied any wrongdoing.
During the two-month trial he claimed senior managers were fully aware of his activities and encouraged him to take risks to make profits for UBS.
But prosecutors claim that in a bid to boost his status and bonuses Adoboli exceeded his trading limits, failed to hedge trades and faked records to cover his tracks.
The court heard had that at one point he was at risk of causing the bank losses of $12 billion.
His arrest in September wiped 10 percent off the bank's share price.
A UBS spokeswoman told AFP: "The UK criminal process is still ongoing. UBS has no comment."
Judge Brian Keith said the jury gave a majority verdict on the first count of fraud and could deliver a 9-1 verdict on the remaining five charges.
The jury had been reduced to five men and five women after two jurors were discharged.
Prosecution lawyer Sasha Wass told jurors during the trial that he was "a gamble or two away from destroying Switzerland's largest bank for his own gain".
"Mr Adoboli's motive for this behaviour was to increase his bonus, his status within the bank, his job prospects and of course his ego," she said.
Adoboli, the privately-educated son of a former UN official, told jurors that he had dedicated his life to benefiting the bank and viewed his colleagues at UBS's London offices as "family".
After completing an internship at UBS while at university in England, he went to work for the bank full time after graduating in 2003.
He joined its exchange traded funds desk in 2006, dealing with funds whose value rises and falls depending on the performance of the markets they track.
By 2007, he and another more senior trader were managing a portfolio worth $50 billion.
It might seem "crazy" that a 26-year-old with just five years' experience was in charge of such a huge portfolio, Adoboli told the jury, but "that's how it was".
The court heard that Adoboli began conducting off-the-books trades in 2008, holding them off the ledger until the market rebounded.
But as the financial crisis took hold, he racked up huge losses, and discrepancies in his trading activities eventually aroused the suspicion of a back office accountant.
Adoboli insisted that what he had done did not make him a "rogue trader".
"It is not fraudulent -- it is finding a way to do your job," he told the court.
The case has drawn comparisons to Jerome Kerviel, the French trader who lost the Societe Generale bank billions with unauthorised bets of 50 billion euros on futures markets.
